Biopyschology

Question 1

The Nervous System

Answer 1

The nervous system is a specialised network of cells in our body
It is our primary internal communication system and it send information around our body using electrical and chemical signals
The 2 main functions are:
- to collect, process and respond to information in the environment
- co-ordinate the working of different signs and cells in the body
The nervous system is divided into tow subsystems:
- The Central Nervous System (CNS)
- The Peripheral Nervous System (PNS

Question 2

The Central Nervous System (CNS)

Answer 2

The CNS is made up of the brain and the spinal cord
It it the origin of all complex commands and decisions

Question 3

The Brain

Answer 3

The brain is a remarkably complex organ comprised of billions of interconnected neurons
- it is highly developed in humans and it is what distinguishes our higher mental functions from other animals
It is divided into two hemispheres and also has distinct lobes
- each lobe is associated with certain types of functions, but ultimately, all of the areas of the brain interact with one another to provide the foundation for our thoughts and behaviours

Question 4

The Spinal Cord

Answer 4

It can be said that the spinal cord is what connects the brain to the outside world
Because of the spinal cord, the brain can act
The spinal cord is like a very small relay station
It not only passes messages to and from the brain, but it also has its own systems of automatic processes, called reflexes
The top of the spinal cord merges with the brain stem, where basic processes of life are controlled, such as breathing and digestion
In the opposite direction, the spinal cord end just below the ribs, whereas the spine extends further

Question 5

The Peripheral Nervous System (PNS)

Answer 5

The PNS transmits messages via nerves, carrying message back and forth between the CNS and the muscles, organs and glands in the periphery of the body
- i.e. everything outside of the CNS
The PNS is further sub divided into the:
- somatic nervous system (SNS)
- autonomic nervous system (ANS)

Question 6

The Somatic Nervous System (SNS)

Answer 6

The SNS is associated with activities traditionally thought of as conscious or voluntary
It is involved in the relaunch of sensory and motor information to and from the CNS
- therefore, it consists of sensory and motor neurones
Sensory neurones can carry sensory information to the CNS
- these are known as afferent neurones and they carry information to the CNS
Motor neurones carry instructions from the CNS to the muscles
- these are known as efferent neurones and they carry information from the CNS

Question 7

The Autonomic Nervous System (ANS)

Answer 7

The ANS controls our internal organs and glands and is generally considered to be outside the realm of voluntary control
It can be further subdivided into the sympathetic and parasympathetic divisions
- the sympathetic nervous system is involved in preparing the body for stress - related activities (fight-or-flight)
- the parasympathetic nervous system is associated with returning the body to routine, day-to-day operations (rest-and-digest)
The two systems have complementary functions, operating in tandem to maintain the body’s homeostasis
- homeostasis is a state of equilibrium, in which biological conditions (such as body temperature) are maintained at optimal levels

Question 8

Divisions of the Nervous System Summary

Answer 8

Nervous system
PNS. CNS
ANS. SNS. Brain. Spinal Cord
SNS. PNS

Question 9

The Endocrine System

Answer 9

The endocrine system works alongside the nervous system to control vital functions in the body
It acts more slowly than the nervous system, but it is equally important as important
It regulates biological process in the body from conception until you die, including the development of the reproductive system, as well as metabolism
The endocrine system is made up of glands that produce hormones

Question 10

Hormones

Answer 10

Hormones are chemical substances that are secreted into the bloodstream and affect any cell in the body that has a receptor for that particular hormone
- lock and key
When a hormone binds to a receptor, the receptor carries out the hormones instruction
Most hormones affects cells in more than one body organ
- e.g. the thyroid gland produces the hormone thyroxine
- this affects cells in the heart to increase heart rate, as well as other cells throughout the body, increasing metabolic rate

Question 11

Fight or Flight

Answer 11

the two systems working together
1 - stressor perceived
2 - the hypothalamus (part of the brain) activates the pituitary gland
3 - this actives the sympathetic branch of the ANS
4 - the sympathetic branch sends a signal to the adrenal medulla (part of the adrenal glands)
5 - the adrenal medulla then releases the hormone adrenaline
6 - adrenaline circulates throughout the body targeting key organs such as the heart and muscles, to beat fastest, blood pressure to rise, increase in breathing rate, dilation of pupils and the inhibitions of digestion and saliva production
7 - when the threat has passes, the stress response is dampened by the parasympathetic branch of the ANS and the body is returned to its resting state (rest-and-digest)
* the ps and s branches work in opposition to each other - they are antagonistic to each other*

Question 12

Neurones

Answer 12

There are 100 billion neurones (nerve cells) in the human system
80% of these are located in they brain
They send signals electrically and chemically
They are the primary way that the nervous system communicates internally and externally

Question 13

Types of Neurones

Answer 13

Sensory neurones
Relay neurones
Motor neurones

Question 14

Sensory Neurones

Answer 14

They carry messages from the PNS to the CNS
They have long dendrites and short axons
They have Nodes of Ranvier which are gaps in the nylon sheath
- the nylon sheath insulates neurones

Question 15

Relay Neurones

Answer 15

These connect sensory neurones to motor neurones or other relay neurones
They have short dendrites and long axons
They make up 97% of ball neurones

Question 16

Motor Neurones

Answer 16

These connect the CNS to effectors (muscles and glands)
They have short dendrite and long axons

Question 17

Neurone Strucutre

Answer 17

Neurones vary in size from 1mm to 1m, but all share the same basic structure
The cell body includes a nucleus which contains all of they genetic material off the cell
Branch like structures called dendrites protrude from the cell body and carry nerve impulses from neighbouring neurones towards the cell body
The axon carries the impulses away from the cell body down the length of he neurone
The axon is covered in a fatty layer of myelin sheath that protects the axon and speed up the electrical transmission of the impulse
If the myelin sheath was continuous, this would have the reverse effect and slow down the electrical impulse
- so the myelin sheath is segmented by gaps called nodes of Ranvier
- this speeds up the electrical impulse by forcing it to ‘jump’ across the gaps along the axon
Finally, at the end of the axon are terminal buttons that communicate with the next neurone in the chain, across a gap known as the synapse

Question 18

Location of Neurones

Answer 18

Motor Neurones - generally in the CNS but have long axons which form part of the PNS
Sensory Neurones - located in the PNS, gathered in clusters called ganglia
Relay Neurones - most are found in the brain and the visual system

Question 19

Electrical Transmission

Answer 19

firing of a neurone
When resting, the inside of the neurone cell is negatively charged compared to the outside
When a neurone is activated, the inside becomes positively charged for a brief second
This causes potential action to occur
- this creates an electrical impulse that travels down the axon towards the end of the neurone

Question 20

Chemical Transmission

Answer 20

Neurones communicate with each other within groups known as neural networks
Each neurone is separates from the next by tiny gaps called synapses
Signals within neurones are transmitted electrically, but signals across neurones are transmitted chemically across a synapse
When the electrical impulse reaches the end of the neurone (the presynaptic terminal) the release for a neurotransmitter is triggered from tiny sacs called synaptic vesicles

Question 21

Neurotransmitters

Answer 21

They are chemicals that diffuse across the synapses to the next neurone in the chain
Once the neurotransmitter has crossed the gap, it is taken up by the postsynaptic receptor site on the dendrites of the next neurone, which are complementary
- (axons take signals to the synapse, the dendrites take signals away)
Here the chemical signal is converted back into an electrical impulse and the process of transmission begins again
- the direction of travel can only be one way because neurotransmitters are released from the presynaptic neurone terminal and received by the postsynaptic neurone at receptor sites

Question 22

Types of Neurotransmitters

Answer 22

There are different types of neurotransmitters
Several dozen types have been identified in the brain, spinal cord and glands
Each has its own specific molecular structure that fits perfectly in the receptor site
- they are complementary (like a jigsaw puzzle)
Neurone transmitters also have a specialist function, such as acetylcholine (ach) is found where a motor neurone meets a muscle and when released will cause a muscle to contract

Question 23

Excitation

Answer 23

When a neurotransmitter increases the charge of a postsynaptic neurone
This increases the likelihood that the postsynaptic neurone will pass on the electrical impulse

Question 24

Inhibition

Answer 24

When a neurotransmitter increases the negative charge of a postsynaptic neurone
This decreases the likelihood that the postsynaptic neurone will pass on the electrical impulse

Question 25

Excitation and Inhibition with Neurones

Answer 25

Neurotransmitters either have an excitatory or inhibition effect on the neighbouring neurone
Serotonin causes inhibition in the receiving neurone, resulting in the neurone become more negatively charged and so less likely to fire
Adrenaline (both a hormone and neurotransmitter) causes excitation in the postsynaptic neurone, resulting in the neurone becoming more positively charged and more likely fire

Question 26

Summation

Answer 26

Whether a postsynaptic neurone fires is decided by the process of summation
The excitatory and inhibitory influences are summed (added up)
- if the net effect on the postsynaptic neurone is inhibitory then it is less likely to fire
- if the net effect on the postsynaptic neurone is excitatory then it is more likely to fire
This happens by the inside of the postsynaptic neurone

Question 27

Post-Mortem Examination

Answer 27

Summary: brain analysed after death to determine whether certain observed behaviour during a person’s lifetime can be linked to structural abnormalities in the brain
Details: used to establish underlying neurobiology of a particular behaviour (e.g. researchers might study a person who displays behaviours while they are alive that suggest possible underlying brain damage)
So when the person dies, the researcher can examine the brain of these individuals and look for abnormalities that might have explained their behaviour (and which are not found in control patients)
An early example of this method was Broca’s work with an patient called Tan, who displayed speech problems when he was alive
- found to have lesions in the area of the brain that is now known to be the Broca’s area - important area for speech production
Have also made it possible to identify some of the areas of the brain responsible for memory and has also been used to establish a link between psychiatric disorders and underlying brain abnormalities

Question 28

Post-Mortem Strengths

Answer 28

A strength of using post Mortem examinations is that they allow for a more detailed examination of anatomical and neurochemical aspects of the brain that would not be possible with non-invasive scanning methods
For example, it enables researchers to examine deeper regions of the brain such as the hypothalamus and hippocampus, that would not be accessible with non-invasive methods, which pose great risks
This is a strength because it allows psychologists to gain a deeper understanding of the role of the brain in human development, behaviour and abnormality
Post mortem examinations have played a central role in developing understanding of schizophrenia
For example, Harrison (2000) suggests that asa direct result of post mortem examinations, researchers have discovered structural abnormalities of the brain and have found evidence of neurotransmitters, both of which are associated with the disorder.
This is a strength because gaining knowledge has not only developed psychologists understanding of why sz developed, it allows for the development of more successful treatment methods

Question 29

Post-Mortem Limitations

Answer 29

A limitation of Post Mortem examinations is that they can sometimes lead to inaccurate data and findings
For example, length of time between death and Post Mortem examinations, drug treatment and age of death are all confounding influences of any difference between case and controls
This is a limitation because the findings obtained from Post-Mortem examinations may be criticised as lacking internal validity making it difficult for conclusions and cause and effect to be drawn
A further weakness is that the approach is retrospective
For example, due to the fact that the individual is already dead, the researcher is unable to follow up anything that arises from the post Mortem concerning a possible relationship between brain abnormalities and cognitive functioning
This is a limitation because it means that the conclusions that can be dawn from post Mortem examinations are often limited

Question 30

Electroencephalogram (EEG)

Answer 30

Summary: a record of tiny electrical impulses produced by the brain’s activity
By measuring characteristics though have patterns, the EEG can help diagnose certain conditions in the brain
Detail: measure electrical activity in the brain
Electrodes (placed on top of the scalp) detect small extricate changes resulting from the activity of the brain cells
When electrical signals from the electrodes are graphed over a period of time, the resulting representation is called an ECG
ECG activity can be used to detect different types of brain disorders (e.g.g epilepsy) or to diagnose other disorders that influence brain activity (e.g. Alzheimer’s)
The four basic ECG patterns are:
- alpha (awake but relaxed)
- beta (awake but physiologically aroused)
- delta and theta waves (sleeping)
When a person is moving from light sleep to deep sleep, the occurrence of alpha waves decrease and are replaced by theta and then delta waves

Question 31

EEG Strengths

Answer 31

A strength of using ECG to measure brain activity is that is created a measure of brain activity functioning in real time (high temporal resolution)
For example, the ECG canine takes a reading of the active brain rather than a passive brain
This is a strength because the researcher can accurately measure a particular task or activity with the brain activity associated with it

A strength of using ECG machines is that they are useful when trying to make a clinical diagnosis
For example, epileptic seizures are caused by disturbed brain activity which means that the normal ECG reading suddenly changes
This is a strength because ECG machines can help diagnose whether someone is experiencing epileptic seizures or other brain activity

Question 32

EEG Limitations

Answer 32

A problem with using ECG readings/machines is that they can only detect activity in superficial regions of the brain
For example, the ECG cannot reveal what is going on in deeper regions of the brain such as the hypothalamus or hippocampus.
This is a weakness because it means that the information gained form ECG machines about brain activity is often limited (unless more invasive procedures are used e.g. inserting electrodes into the brain to measure deeper brain activity

One disadvantage of ECG is that it has poor spatial resolution
Spatial resolution refers to the smallest feature (or measurement) that a scanner can detect and is an important feature of brain scanning techniques. Greater spatial resolution allows psychologists to discriminate between different brain regions with greater accuracy. ECGs only detect the activity in superficial regions of the brain
Consequently, ECGs are unable to provide information on what his happening in the deeper regions of the brain (such as the hypothalamus), making this technique limited in comparison to the fMRI, which has a spatial resolution of 1-2mm

Question 33

Event-related potential (ERP)

Answer 33

Summary: Isolating the electrophysiology response of the brain to specific sensory, cognitive or motor event by statistically analysing the ERP data
Detail: EPRs are small voltage changes in the brain that are triggered by specific events or stimuli (e.g. cognitive processing of a specific stimuli)
EPRs are difficult to pick out from all the other electrical activity being generates in the brain at a given time
To establish a specific response to a target stimulus required many presentations of the stimulus are these responses are then averaged together
any extraneous neural activity that is not related to to the specific stimulus will not occur consistently, whereas activity linked to the stimulus will - this has the effect of cancelling out the background neural “noise”, making the specific response to the stimulus stand out more clearly
EPRs can be split into 2 categories:
1 - waves occurring in the first 100 milliseconds after presentation of the stimulus are termed ‘sensory ERPs’ as they reflect an initial response to the physical characteristic of the stimulus
2 - ERPs generated after the first 100 milliseconds reflect the manner in which the participant evaluated the stimulus and are termed ‘cognitive ERPs’ as they are demonstrating information processing

Question 34

ERP Strengths

Answer 34

An advantage of the ERP technique is that is has good temporal resolution
It takes readings very millisecond, meaning it can record the brain’s activity in real time as opposed to looking at a passive brain
This leads to an accurate measurement of electrical activity when undertaking a specific task

An advantage of the ERP is that it is an non-invasive technique
I like other scanning techniques, such as Positron Emission Tomography (PET), ERP does not use radiation or involve inserting instruments directly into the brain and are therefore virtually risk-free
Furthermore, ERPs are much cheaper techniques in comparison with the fMRI scanning and are therefore more readily available
Consequently, this should allow more patients/ppts to undertake ERPs, which could help psychologists to gather further data on the functioning human brain and therefore develop our understanding of different psychological phenomena, such as sleeping, and different disorders like Alzheimer’s

Question 35

ERP Limitations

Answer 35

One disadvantage of ERP is that it has poor spatial resolution
Spatial resolution refers to the smallest feature (or measurement) that a scanner can detect, and is an important feature or brain scanning techniques. Greatest spatial resolution allows psychologists to discriminate between different brain regions with greater accuracy
ERPs only detect activity in superficial regions of the brain. Consequently, EEGS and ERPs are unable to provide information on what is happening in the deeper regions of the brain (such as the hypothalamus), making this technique limited in comparison to the fMRI, which has a spatial resolution of 1-2 mm
A further weakness of using ERPS is that the output can only be interpreted by a trained professional
For example, psychologists using ERPs require intense and expensive training in order to fully appreciate the activity measure from the ERP
This is a weakness because such training can increase the cost of research and with limited funding in specific research areas, this can minimise the use of ERPs (attempting to save money)

Question 36

Functional magnetic resonance imaging (fMRI)

Answer 36

Summary: method used to measure brain activity while a person is performing a task
Detects radio waves from changing magnetic fields which enables researchers to detect which areas of the brain are rich in oxygen (and therefore active)
Detail: a technique for measuring changes in brain activity while a person performs a task
Does this by measuring changes in blood flow in particular areas of the brain (indicates oxygen in the area)
If a particular area of the brain becomes more active, there is increased demand for oxygen in that area
The brain responds to this extra demand by increasing blood flow, delivering oxygen in the red blood cells
As a result in these changes in blood flow, researchers are able to produce maps showing which areas of the brain are involved in particular mental activity

Question 37

FMRI Strengths

Answer 37

FMRI scans can be praised for being non-invasive
For example, it does not involve the insertion of any instruments into the body, nor does it expose the brain to potentially harmful radiation as is the case with some other scanning techniques
This is a strength because it means that individual’s behaviours can be investigated without their physical, mental or psychological health being places at risk

FMRI offers are more objective and reliable measure of psychological processes than is possible with verbal reports
For example, blood volume can be accurately measures to see which parts of the brain are being utilised in certain tasks so research using fMRI scans are not simply relying of observations of the ppts behaviour or self reports from the ppts themselves
This is a strength because it means that fMRIs are a useful way of investigating psychological phenomena that people would not be capable of providing in verbal reports whilst also removing any chance of bias (from observations/self-reports)

FMRI scans have good spatial resolution
Spatial resolution refers
To the smallest feature (or measurement) that at scanner can detect, and is an important feature of brain scanning techniques. Greater spatial resolution allows psychologists to discriminate between different brain regions with greater accuracy. FMRI scans have a spatial resolution of approx 1-2 mm which is significantly greater than other techniques (EEG, ERP, etc.)
Consequently, psychologists can determine the activity of different brain regions with greater accuracy when using fMRI, in comparison to when using EEG and/or ERP

Question 38

FMRI Limitations

Answer 38

FMRIs are not a direct measure of neural activity in particular brain areas
For example, fMRIs only measure changes in blood flow in the brain which makes interpreting fMRI scans high complex
This is na weakness because it is not truly a quantitive measure of mental activity in these brain areas

FMRI scans have poor temporal resolution
Temporal resolution refers to the accuracy of the scanner in relation to time, or how quickly the scanner can detect changes in brain activity
FMRI scans have a temporal resolution of 1-4 seconds which is worse than other techniques (e.g. EEG/ERP which have a temporal resolution of 1-10 milliseconds)
Consequently, psychologists are unable to predict with a high degree of accuracy the onset of brain activity

The sample sizes for fMRI research are often small/unrepresentative
For example, research usually has a limited amount of funding an using fMRI scans often requires lots of money (for upkeep of tigger machines, training for researchers to learn how to effectively use the machines)
This is a weakness because this makes the research difficult to generalise/gives research low population validity

Question 39

Introduction to Localisation of Function in the Brain

Answer 39

Localisation of function refers to the theory that functions such as movement, speech and memory are performed in distinct regions of the brain (localised)
the opposite view is that the brain acts holistically to perform functions
Different areas within the localisation theory are:
- different regions of the brain
- functions that are associates with those regions
- the extent to which the research evidence support localisation of function

Question 40

Hemispheres of the Brain

Answer 40

Our brains are divided into 2 symmetrical halves
- the left and right hemisphere
There is some hemispheric lateralisation
- i.e. some of our physical and and psychological functions are controlled or dominated by a particular hemisphere
- for example, language centres are found in the left hemisphere and Visio spatial tasks ate best performed by the right
As a general rule, each hemisphere controls the opposite (contralateral- contralateralised wiring) side of the body

Question 41

Lobes of the Brain

Answer 41

The cortex (outer layer of the brain) of both hemispheres is subdivided into four centres, or lobes, of the brain
Each of these loaves is associated with different g functions, and damage to that specific areas in the lobes means that the functions associated with that area will also be affected

Question 42

Motor area

Answer 42

Lobe - frontal
Area - found at the back of the frontal lobe
Function - controls voluntary movement in the opposite side of the body
Results of damage - loss of muscle function (muscles aren’t damaged - your brain that controls them is)
- this could be loss of control over fine motor movements u to paralysis following severe trauma
- effects are in opposite side of body to damage

Question 43

Somatosensory area

Answer 43

Lobe - parietal
Area - found at the front of the parietal lobe, separates from the motor area by a fold called the central sulcus
Function - detects sensations (e.g. touch, heat, pressure) from the opposite side of the body
Result of damage - loss of sensation
- neglect symptom - reduced awareness of stimuli
- agnostic - inability to identify objects and faces
(Effects in opposite side to damage)

Question 44

Visual area

Answer 44

Lobe - occipital
Area - found at back of the occipital lobe
Function - Brain’s visual processing centre
- each hemisphere’s occipital lobe received infro from the contra lateral visual field
Result of damage - leads to partial or complete lindens
- called cortical blindness —> the person s unable to see but there is no damage to the structure of the eye

Question 45

Auditory area

Answer 45

Lobe - temporal
Area - found at the top of the temporal love
Function - receives and analyses speech-based info
Result of damage - leads to partial or complete hearing loss
- known as cortical blindness —> person is unable to hear but there is no damage to the structure of the ear

Question 46

Language centres of the brain

Answer 46

Unlike the motor area, somatosensory area, visual area and auditory rea, which are all found in both hemispheres, in most people language is restricted to the left hand side of the brain
The 2 language centres are Broca’s area and Wernicke’s area

Question 47

Broca’s area

Answer 47

Located in left frontal lobe
Responsible for speech production
Damage results in Broca’s aphasia:
- patient understands wat is being said to them
- however, their own speech is characterised by being slow, laborious and lacking in fluency
- often have difficulty with prepositions (positioning words) and conjunctions (connecting, joining words)
- demonstrated by Broca’s famous patient - the case of ‘Tan”

Question 48

Wernicke’s Area

Answer 48

Located in the left temporal lobe
Responsible for speech comprehension
Damage results in Wernicke’s aphasia
- patient has difficulty understanding speech
However, they have no problem in producing speech
- as a result, the speech they produce i fluent but meaningless and will often contain neologisms (nonsense words)

Question 49

Evidence for localisation - case studies

Answer 49

Clinical case study research demonstrates loss of certain functions if damage is caused to particular areas of the brain
For example:
- the case of Tan )aphasia)
- the case of Clive Wearing (amnesia - hippocampus)
- Phineas Gage (frontal lobe damage)
This is a strength of localisation theory because these case studies do suggest that these functions are localised in certain areas
However, these individuals experience very specific Bain damage - their brain damage is specific to them
Are we able to to take these very specific and personal findings and generalise them to all cases f brain damage in support of the theory

Question 50

Evidence for localisation - brain scans

Answer 50

Brain scan reserach further supports these case studies by demonstrating how many language are localised to particular areas of the brain
For example:
- healthy ppts show activation in Broca’s area during a reading out loud task and Wernicke’s area during a listening task —> Peterson et al, 1988 (used brain fMRI scans)
- there is activation of different parts of the prefrontal cortex when accessing semantic and episodic memories (Bucker & Peterson, 1996)
This type of research is a strength because it is much more scientific and objective (unlike case studies that are subjective)
No room for bias in interpreting results
Results the brain scans show cannot be interpreted in different ways - the results are what they are

Question 51

Evidence for localisation - neurosurgery

Answer 51

Neurosurgery is based on theory of localisation
It works by destroying parts of the brain that are thought to contribute to psychological problems
For example, in OCD, a region of brain called cingulate gyrus appears to be more active. The bilateral cingulotomy is designed to surgically interrupt this circuit. Surgeons can either burn away tissue by heating the tip of the electrode, or use a non-invasive tool known as a game knife to focus beam of radiation at the target site. An alternative is the capsulotomy where surgeons insert probes through the top of the skull and down into the capsule, a region of the brain near the hypothalamus that is part of the circuit. They then heat the tips of the probes, burning away tiny portions of tissue
In general review of research, Cogrove and Rauch (2001) sported thar cingulomoty was effective in 56% of OCD and capsulotomy in 67%
The surgery wouldn’t work if localisation theory wasn’t true
If this area of the brain wasn’t acclimated with OCD then the surgery wouldn’t work
So it must mean that this area of the brain is specific to that function
No other functions damaged in the surgery, which you would expect if holistic theory was true
However, you would expect all patients to have been helped but this wasn’t the case, going against localisation theory

Question 52

Evidence against localisation theory - language localisation research

Answer 52

Some recent research with more advanced brain imaging techniques has suggested that lanaguge systems are more distributes rather than being localised to Broca’s and Wernicke’s areas
- one 2106 review found only 2% modern researchers think that language is completely controlled by these areas
Seems as of language functioning is more widely distributed with ‘language streams’ being identified in regions in the right hemisphere ad subcortical areas such as the thalamus
Contradicts localisation theory although as motor and somatosensory functions are highly localised, these findings may actually suggests that the correct approach in arguing for localised vs holistic nature of brain is dependent on the function we are considering

Question 53

Evidence assistant localisation theory - Lahsely’s rats reserach

Answer 53

Lashely trained rates to run around maze and destroyed areas of their brain cortex (between 10% to 50%) destroying tissue in almost every area that allowed rats to stay alive
Found that is was the amount of brain destroyed, not the specific part of the brain that was destroyed, which led to the worsening of performance
Lashely concluded that higher cognitive processes, such as learning and memory aren’t localised but are instead distributed in a more holistic way across brain and that any healthy area of the cortex can perform damaged areas
However, maybe the brain compensates if it is over damaged
We are humans, not rats

Question 54

Localisation vs lateralisation

Answer 54

Compared to the left hemisphere, the right hemisphere can only produce rudimentary words and phrases
However, it does contribute emotional context to what is being sad (i.e. interrogative, happy or sad tone of voice, understanding humour, Sarcasm, metaphors and in direct requests)
This has led to suggestions that left hemisphere is the analyser and right hemisphere is the synthesiser which in turn led to idea that left Brain people are more scientific ad logical and right brain people who are more creative

In most individuals without sz, the left hemisphere is slightly larger than the right hemisphere (ceberal asymmetry)
However in some individuals with sz, the right hemisphere is notably larger than the left (reversed cerebral asymmetry)
This deterioration to left hemisphere could lead to poverty of language (alogila) which is often seen in sz

Question 55

Weakness of Lateralisation

Answer 55

However, one weakened is that this idea that the left hemisphere is the analyser and the right hemisphere is the synthesiser is wrong
Research suggests that people don’t have a dominant side of their scans which creates a different personality. Nielsen et al (2013) analysed brain scans for over 1000 people aged 7 to 29 and while they did find that people used certain hemispheres got certain tasks (which is evidence for lateralisation), there is no evidence of a dominant side. So mathematicians don’t have a dominant left hemisphere and artists don’t have a dominant right side
Suggests the notion of right or left brained people is wrong

Question 56

Lateralisation of Vision

Answer 56

While language is lateralised, many other functions aren’t
- motor, somatosensory and vision areas appear in both hemispheres of the brain
In case of motor area, there is contractural wiring
- idea that fright hemisphere control’s movement left of left side of body and vice versa
In case of vision, it’s even more complex
Vision and both contralateral (opposite side wiring) and ipsilateral (same side wiring)
Each eye has left visual field and right visual field from which it receives light
The left visual field of both eyes is connected to the right hemisphere
The right visual field of both eyes is connected to left hemisphere
This enables the visual areas to compare slightly different perspective from each eye and Aidan’s depth perception
There is similar conteralateral and ipsilateral wiring for auditory input to the auditory area which helps us locate the source of sounds

Question 57

Strength of lateralisation

Answer 57

A strength is that there is empirical research evidence that suggests the two hemispheres do process information differently, this isn’t just theoretical model of how Brain processes information
Fink et al (1996) used PET scabs to identify which brain areas were active during a visual processing task. When asked to focus on finer details in an image (e.g. individual trees) showed regions of left hemisphere are active. When asked to focus on global detail (e.g. the whole forest) regions of the right hemisphere are more active
At least as far as visual processing is concerned, hemispheric lateralisation is a feature
- PET scans show objectivity however lack mundane realism

There is research to support lateralisation can actually change over time
Szaflarski et al (2006) found language became more lateralised to left hemisphere with increasing age in children and adolescents but after age 25, lateralisation decreased with each decade of life

Question 58

Split brain research context

Answer 58

The corpus callosum is a large system of nerve fibres that connect the left and right hemisphere
A split-brain operation involves severing this
This is usually done to reduce epilepsy (as during an epileptic seizure the brain experiences excessive electrical activity between the hemispheres)
This has provided neuroscientists and psychologists with a way of studying how the hemispheres function when they can’t communicate with each other

Question 59

Split brain research study

Answer 59

Sperry (1968) studies 11 split brain patients and compared to non-split brain patients
Shown a computer screen where either rods or pictures to be shown to either the LVF or RVF
Hands are on hidden objects - can’t be seen but can be felt
(Order = scenario, the information is received by, the response of the ppt, explanation)

Picture or word of an object is shown to ppt’s right visual field - the left hemisphere - the ppt could describe what they had seen, either verbally or in writing - this is because language is lateralised in the left hemisphere

Paiute or word of an object is shown to the patients left visual field and asked to describe it - the right hemisphere - the ppt couldn’t describe they they had seen either verbally or in writing - this is because the information received by the right hemisphere couldn’t be transferred to language centre in left hemisphere because the corpus callosum have been served

Picture or word of an object is shown to the patient’s left visual field and asked to select of matching object - the right hemisphere - the ppt couldn’t describe what they had seen but could select a matching object (e.g. a watch is they were shown a watch) or a semantically similar object (e.g. an ashtray is shown a cigarette) out of sight using their left hand - suggests that the right hemisphere does have language compression but not speech or writing
Picture or word of an emotional object (e..g a nude pinup picture) is shown to the patient’s left visual field - the right hemisphere - the ppt couldn’t describe what they had seen but did have an emotional response e.g. giggling or blushing - this suggests that the right hemisphere appears to experience its own emotional reaction

Conclusions - certain functions are lateralised in tge brain
- support functions that the left hemisphere is verbal and the right side is ‘silent’

Question 60

Split brain research evaluation

Answer 60

Research support from more recent research including work from Michael Gazzaniga (1989)
He had the same findings as Sperry - could say words presented to the right visual field bu not the left visual field
Also found that ppts could draw with their left hand words presented to the LVF showing, like Sperry said, the right hemisphere has language comprehension
Shows external reliability as consistency over time, supporting research supported

Lack of control over variables due to it being a quasi experiment
A quasi experiment is the IV is a naturally occurring difference between groups of people
For example, split-brain patients all had severe epilepsy and the neurotypical control groups didn’t
This is a major confounding variable (as only the split-brain patients had epilepsy) and it could be being neurodivergent itself explains the split brain task results, not the actual split brain

The research is oversimplified and the results are typical of the right-handed men

Question 61

Introduction to plasticity and functional recovery of the brain after trauma

Answer 61

The brain isn’t s static organ and the functions and processes of the brain can change as a result of experience and injury
Neural plasticity is the apparent ability of the brain to change and adapt its structures and processes as a result of experience and new learning
This links directly to idea of functional recovery the way that certain ability of the brain may be moved or distributed rather than lost following trauma to the brain

Question 62

Neural plasticity

Answer 62

As each neuron matures, it sends out multiple branches
This plasticity (‘brain change’) increases the number of syntactic contacts from neuron to neuron
This is important because synapses don’t just ‘pass messages’ from one neurone to another, they also help strengthen the connection between neurons
The number of connections and the strength of those connections are linked to intelligence and other higher ability skills

While plasticity occurs throughout life, it is especially relevant during the early “critical years” when brain plasticity enables the senses, language, and together skills develop
Therefore than surprising that during infancy the brain experiences rapid growth in the number of synaptic connections

At birth, each neuron in the cerebral cortex has approx 2,500 synapses
By the time a child is 3, the number of synapses is approx 15,000 (6x as many) synapses per neuron

The strength of synapses can be increased or decreased, depending on their activity levels
Very active synapses are likely to become stronger, embedding knowledge, skills and memory further (long-term potentiation)
Those that are less active tend to becom weaker (long-term depression)
As we mature, the connections we don’t use are deleted
This is called neural pruning (Purcell & Zukerman, 2011) - use it or lose it situation

Question 63

Further knowledge on long-term potentiation

Answer 63

When a neurone is activated e.g. by reading a piece of text, actin (a protein side cells) causes temporary movements on neurones towards other neurons with which they are connected
This is quite normals and research by University of California found that this activation lasts up to 5 minutes and then disappears quite quickly
But if the neurone isn stimulated repeatedly (by repeating task 4 times in one hour), the synapse would physically split, forming new synapses and a potentially permanent neural change
So, we can physically consolidate a memory though repetition or exposure to experience

Question 64

Long-term synaptic plasticity research

Answer 64

Long-tern synaptic plasticity forms the model for memory storage, and a famous study by Maguire et al. (2000) demonstrates this
She studies 16 London taxi drivers and found the volume of grey matter (where there is a high concentration of neurones) in the posterior hippocampus of London taxi drivers’ brain was positively correlated with their time as a taxi drivers and that there were significant between the taxi drivers’ brains and those of controls
It’s important to note that this area of the brain is involved in memory and spatial navigation
This shows that the brain can permanently change in response to frequent explosive to a particular task

Question 65

Neural plasticity strengths

Answer 65

One strength of research into neural plasticity is there there is a large body of objective research supporting the theory that the brain can change and adapt as a result of experience and learning and this occurs across the lifespan and across a range of experiences
- Mechelli et al. (2004) found that learning a second language increases the density of grey matter in the left parietal cortex and that this density is influence by the fluency attained (more fluent, more density) and the age at which the second language was learnt (younger age, more density)
- Lazar et at. (2005) found how experienced meditators had a thicker cortex (the outer surface of the brain that is associated with higher level cognitive processes; this was especially thicker in arrears related to attention and sensory processing) compared to non-meditators
- Draganski et al. (2006) imaged the brains of medical students three months before and after their final exams. Changes were seen to have occurred in the posterior hippocampus and the parietal cortex
- Boyke (2008) found that event at 60+, learning a new skills (juggling) resulted in increased neural growth in the visual cortex
- Bezzola et al. (2012) showed how 40 hours of golf training increased motor cortex activity in new golfers aged 40-60
- Kuhn et al. (2013) found significant increase in right hippocampal formation and the right prefrontal cortex in a video gaming training group (that trained for 2 months for at least 30 minutes per day with a platformer game) compared with a control group
This is a strength because it shows there is a large body of objective, empirical evidence for neural plasticity

Question 66

Negatives of neural plasticity

Answer 66

Neural plasticity isn’t always a good thing
- it may have negative consequences
For example, taking part in addictive behaviours (which activates the dopamine pathways in the mesolimbic system) can result in a umber of neural changes
One of these is that the dopamine stimulated neurons in the area now the brain called the dorsal striatum which is involved in forming habitats and can lead to tolerance and relapse in addicts

A second example is phantom limb pain syndrome, a condition in which patients experience sensation, whether painful or otherwise, in a limb that doesn’t exists
It has been reported to occur in 80-100% of amputees and is often resistant to treatment
The exact cause isn’t known but it is thought to be due to cortical reorganisation of the somatosensory cortex
After an amputation the brain may remap that part of the body’s sensory circuitry to another part of the body
In other words, because the amputated area is long longer able to receive sensory information, the information is referred elsewhere, from a missing hand ton a still-present cheek for example
So when the check is touched, it’s as though the missing hand is also being touched
Because this is yet another version of tangles sensory wires, the result can be pain
This is a limitation because it suggests that brain plasticity isn’t always a good thing

Question 67

Functional recovery

Answer 67

An example of neural plasticity than can occur after trauma such as stroke or damage following injury
Healthy brain areas may take over functions of those areas that are damaged, destroyed or missing
It may do this by forming new synaptic connections close to the areas of damage
These secondary neural pathways are activated to enable function to continue, often in the same way as before

Question 68

Stages of functional recovery

Answer 68

1. Axonal sprouting
   - undamaged axons grow new nerve endings to reconnect neurones whose links were injured or severed
   - undamaged axons an also sprout nerves endings and connect with other undamaged nerve cells, forming new neural pathways to accomplish a needed function
2. Denervation suspersensitivity
   - undamaged axons that do a similar job to those that are damaged become aroused to a higher level to compensate for those that are lost
   - however this can have negative consequences e.g. being over sensitive to pain messages
3. Recruitment of homologous reads of the opposite side of the brain
   For example, if Broca’s area was damaged ……

Question 69

Functional recovery strengths

Answer 69

Real-world applications. Neuroscientists have suggested that this process can occur quickly (spontaneous recovery) but then after weeks or months it can slow down, at which point rehabilitation therapy may be required to further recovery

Understanding of the processes involved in plasticity and functional recovery has been helped contribute to neurorehabilitaion
One such example is constraint-induced movement therapy to help patients who have had strokes, where they repeatedly practise using the affected part of their body (e.g. an arm) while the unaffected arm is restrained. Research has shown that CIMT significantly increases function and strength following several hours of therapy
CIMT works because the repeated movement and work causes more actin the neurones and causing more downwards pressure to next neurone causing more neurone branches to synapses, causing more functional recovery
Gives validity to functional recovery because it shows that it works in practice

Question 70

Functional recovery limitation

Answer 70

However one point to bear in mind for functional recovery si that factors such as age and level of eduction may impact recovery rates
Elbert et al (1994) concluded that the capacity for neural reorganisation is much greater in children than in adults, meaning that neural regeneration is less effective in older brains
Schneider t al (2014) found that 40% of people who achieved a disability-free recovery had more than 16 years of education compared to 10% of those who had less than 12 years of eduction. Therefore, we must consider individual differences when assessing the likelihood of functional recovery in the brain after trauma

It is also worth remembering that a lot of research studies into functional recovery is based on a small samples of patients or case studies of individual patients
Less evidence gathered from small group, may be more biases likely such as gender or cultural biases, and therefore can’t be applied to general population

Question 71

Infradian rhythms

Answer 71

Take longer than 24 hours to complete

Question 72

The menstrual cycle

Answer 72

Governed by monthly changes in hormone levels
The cycles refers to first day of women’s period to the day before her next period
Typical menstrual cycle takes about 28 days to complete but can be anything from 14-60 days
Further detail:
The menstrual cycle is a monthly sequence of events in females
During the cycle, an egg is released and the uterus is prepared for implantation is fertilisation happens
Girls are born with around 1 million eggs already present in their ovaries
There are 4 stages of the cycle
Stage 1 - menstrual stage, bleeding starts (menstruation) on ay 1 and lasts for about 4 days, this is the uterus lining breaking down
Stage 2 - follicular stage, the uterus forms a thick spongy lining ready for fertilised eggs, day 4-14
Stage 3 - ovulation phase, an egg develops and is released form an ovary (ovulation) into the uterine tube at about day 14 (peak fertility peak)
Stage 4 - luteal phase, uterus lining maintained or about 14 more days to about day 28, if a fertilised egg doesn’t implant the uterus lining breaks down
Hormones controlling menstrual cycle are made in the pituitary gland
Follicle stimulating hormone (FSH) makes a follicle (egg plus surrounding cells) mature in the ovary, FSH is only made in first half of the cycle and inhibited later so only one follicle matures per cycle
Luteinising hormone (LH) stimulates ovulation and inhibits FSH production, LH causes the remains of the follicle to develop into a structure called the corpus luteum
The corpus luteum produces hormone oestrogen and progesterone, the control growth of uterus lining
The levels of the 4 hormones fluctuate during the menstrual cycle

Question 73

Menstrual cycle and exogenous zetigebers

Answer 73

The menstrual cycle is an endogenous system, in that is it controlled by internal factors (hormones)
However, it can be influenced by exogenous zetigebers, i.e. factors external to the body
One such exogenous factor is the menstrual cycles of other women
During their menstrual cycle, a woman will secrete pheromones
Pheromones are substances which are secreted to the outside of the body by an individual and received by a second individual of the same species
Stern & McMlintock (1998) demonstrated how menstrual cues May synchronise as a result of the influence of pheromones:
- used 29 women with a history of irregular periods
- samples of pheromones were gathered from 9 different ppts at different stages of the menstrual cycle
- they were gathered by asking women:
~ place a cotton wool pad in their armpit of at least 8 hours on each day of their menstrual cycle
- the pads where then treated with alcohol and frozen
- on day 1, the remaining 20 women day day 1 of cycle pads rubbed on their upper lip
- on day 2, they had day 2 of the women’s cycle pads rubbed on their upper lip and so on
- found 68% of women experienced changes to their own menstrual cycle which brought them closer to the cycle of their ‘odour donor’

Also been suggested that male pheromones may also be an exogenous factor than can influence the menstrual cycle
McClintock (1971) reported that women work withy men have much shorter menstrual cycles and suggested this could be because male pheromones may ‘reset’ a woman’s biological clock for her menstrual cycle

Question 74

Infradian rhythms menstrual cycle AO3

Answer 74

It may be that the role of pheromones play in menstrual cycle have an evolutionary basis
Pregnancies may also become synchronised. In EEA (environment of evolutionary adaptive ness) a number of mothers would have died in childbirth while their child might have survived. This would allow other new mothers to feed the child so it survives and can be looked after and taken care of
It is also advantageous for women to be around men to have much shorter menstrual cycles because they are fertile more often, so it increases their chances of a successful reproduction

However, it is also worth remembering that there are methodological limitations of synchronisation studies
There are many EVs and CVs that can effect changes to the menstrual cycle
These can include:
- stress
- diet
- life style
- certain medications
- perimenopausal
This can explain why findings into synchronisation of menstrual cycles in women aren’t consistent
- not all research have managed to replication these findings
This a is a limitation because it doesn’t suggest that menstrual synchrony studies are flawed

However, there is some evidence of reliable findings into this area
For example, Stern and McClintock (1998) based their work on an earlier study by Russel et al (1980). Russell applied the pheromones of one women (using the same cotton pad technique) to a group of sexually inactive women every day for 5 months. There was also a control group of sexually inactive women who received same treatment but had a clean cotton pad rubbed on their upper lip. The ppts didn’t know which group they were in. A record was kept of their menstrual cycles and at the end of the experiment, four of of the five women in the pheromone group had menstrual cycles that synchronised within a day of the pheromone donors
Shows reliability and therefore validity

Question 75

SAD

Answer 75

Seasonal affective disorder (SAD) is a depressive disorder that is a type of infradian rhythm known as a circannual rhythm because it repeats on a yearly cycle
Further information:
- type of depression that comes and goes in a seasonal pattern, also sometimes known as winter depression, because symptoms are usually more apparent and more server during the winter time (symptoms can be felt in summer rather than winter, thought much less frequently)
The evidence suggests that SAD is related to seasonal variations in productions of melatonin, which is a hormone secreted by the pineal gland
Melatonin affects the production of the neurotransmitter serotonin which is implicated in depression
Melatonin is produced predominantly at night (i.e. darkness) and so more is produced during the dark winter months
There is a negative correlation between melatonin and serotonin
- as melatonin goes up, serotonin goes down and mood goes down

Question 76

SAD Evolution

Answer 76

Strength research into SAD is that theory has predictive validity
The means theory can make accurate predications about occurrence of SAD
For example, Terman (1988) found nearly 10% of those living in New Hampshire (a northern part of the US) experienced SAD, compared to only 2% in southern state of Florida
This would be expected because New Hampshire in the north has shorter days in winter i.e. darker whereas Florida in the south has longer days than higher i.e. lighter
This is a strength because it adds validity to the melatonin explanation of SAD

Second strength is there is real-world applications with development of therapies specific for SAD
Phototherapy (or light therapy), exposed patients being exposed to a box which stimulated very strong light to reset the body’s internal clock and is found to reduce effects of SAD in about 80% of people and is regarded as a safer treatment compared to antidepressants
Both adds validity to theory that SAD is linked to lack of light and the impact that has on the production on both melatonin and serotonin, while also helping improve people’s quality of life

However, some users of phototherapy report headache and eye strain
In addition, research by Rohan et al (2009) compared people with SAD who where treated with phototherapy to a group who received CBT and found a relapse rate of 46% over successive winters for the phototherapy group compared to 27% of CBT group
Both could be used
- phototherapy is available short term and has 80% success rate
- can be accessed very quickly upon relapse
- CBT could be sued alongside this as it’s not as readily available but can help prevent relapse

Question 77

Ultradian rhythms

Answer 77

Take less than 24 hours to complete
- i.e. occur more than once over the course of the day

Question 78

Sleep Cycle

Answer 78

Sleep cycle is one of most intensively researched ultradian rhythms
Researchers have found that there bare 5 stages in in sleep that are based on a 90 minute ultradian cycle
- a cycle that continues throughout then course of the night
Each of the 5 stages in the sleep cycle is characterised by a different level of brain wave activity
These can be measured using EEGs:
- measures electrical impulses in the brain using electrodes that are placed on the scalp

Question 79

Stage 1

Answer 79

This is the only stage you are in once
A light sleep from which you can be easily woken from
- most people would deny being asleep
The body releases
Heart rate and temperature fail
Hypnogogic state may occur
- quite vivid perceptions e.g. falling sensation
Myclonic jerks may occur
Characterised by alpha waves (mid frequency - often around 8-12Hz, short amplitude)
- associated with being relaxed

Question 80

Stage 2

Answer 80

A light sleep from which you can be easily woken, although minor nosies probably won’t disturb you
The body continues to relax
Heart rate, blood pressure and temperature fall
Characterised by alpha waves (high frequency, short amplitude) and sleep spindles (brain activity following muscle twitching, each lasting approx 25 seconds)

Question 81

Stage 3&4

Answer 81

A deep sleep from which you can’t be easily woken
During stage 4r sleep, body temperature, heart rate and blood pressure drop to their lowest point and growth hormones are secreted
Sleep walking, sleep talking and night terrors can occur in stage 4 sleep
- however its a dreamless stage of sleep
Characterised by delta waves (low frequency - 0.5-4Hz, high amplitude)
Also known as slow wave sleep (SWS)

Question 82

Stage 5

Answer 82

Paradoxical sleep
- deepest stage of sleep but brain waves that most closely resemble being awake
Heart rate and blood pressure increase and breathing becomes faster and more regular
Rapid eye movement, so also known as REM (rapid eye movement) sleep
Body is paralysed
- stop you acting out your dreams
- links to sleep paralysis
Dreaming occurs
Hardest stage to wake someone from
EEG activity of theta waves, which closely resembles activity in the awake brain

Question 83

Sleep Cycle Evolution

Answer 83

Strength is that research into sleep cycle has improved our understanding of age-related chnages in sleep
For example, Obayan et al (2004) carried out meta-analysis of 65 studies of sleep patterns across the life span, with ppts aged from 5-102 years old. The most dramatic finding was decrease of SWS (stages 3&4) from 24% total at age 5 to 9% total at age 70. This streaky decrease in SWS is significant as early as age 30. As stage 4 appears to have a restoration purpose (growth hormones are released), this means that as we get older asleep has less and less or a restorative function. This may explain various issues in older age, such as a reduced alertness
This is a strength because we can use this understanding gained from reserach to encourage people to make use of relaxation and medication as they get older to help increase SWS

One limitation of ultradian rhythm research is that is has found significant variation between people
For example, Tucker et al (2007) found large differences between ppts in terms of the duration of each sleep stage, particularly stages 3&4. It has been suggested that these differences are biologically determined
This is a limitation because it makes it difficult to describe a ‘normal’ sleep cycle ultradian rhythm in any meaningful way

Research into the sleep cycle is carried out in sleep labs using EEGs
Strengths:
- difference et variables such as noise, caffeine intake and screen time can be controlled for the gain accurate results
~ internal validity
- no demand characteristics as it is rather difficult to change how much you sleep if you’re tired and you have no control over your sleep cycle
Limitations:
- sleep labs aren’t representative of sleep we get at home - sleep we get at home won’t have all these variables controlled
~ lacks external validity
~ cannot generalise
- people may not sleep as well in a foreign environment
~ lack of internal validity

Question 84

Circadian rhythms

Answer 84

These occur across a 24-hour cycle

Question 85

Sleep-wake cycle

Answer 85

The most obvious and most researched example of a Circadian rhythm is the sleep-wake cycle
We tend to go to bed and wake up at approx similar times each day
The sleep-are cycle is also governed by endogenous pacemaker
- a biological ‘clock’ called the SCN (suprachiasmatic nucleus)
This is a small group of cells that lies within the hypothalamus, just above the optic chiasm which takes in information about the amount and quality of light taken in by the eye
Light can rests the SCN, which suggests that daylight is an important exogenous zeitgiber in the sleep wake cycle

Question 86

Sleep-wake cycle reserach

Answer 86

Michel Siffre, a French cave explorer, spent nearly 7 months living in a cave in Texas, deep underground with no exogenous zeitgebers to tell him time time it was
- no natural light, no clocks, no TV, no radio
He ate and slept when he wanted to, lights came on when he woke up and turned off when he went to sleep
His Circadian rhythm sleep-wake cycle therefore allowed to ‘free-run’
At first, his sleep-wake cycle was fairly erratic, ranging from 25-32 hours
It eventually smelled at 24.9 hours instead of 24 hours

There have been other, similar results recorded
For example, Weber (1979) had ppts spend 4 weeks in a bunker deprived of natural light, and again found that all (but one) ppts settled into a 24.9 sleep-wake cycle

Question 87

Sleep-wake cycle research conclusions

Answer 87

1. Our natural sleep-wake cycle is longer than 24 hours
2. As his sleep-wake cycle was regularly 24.9 hours once it settled, this is evidence of an endogenous pacemaker playing a role in our sleep-wake cycle
3. However as we in real world we live to 24 hours, not 24.9 hours, this suggests that exogenous zeitgebers (external factors) also play a role
4. But we mustn’t overestimate the influence exogenous zeitgebers have on our internal biological clock
   Folk et al (1985) studied 12 people who lived in a dark cave for 3 weeks, in which clocks were provided
   They were asked to go to bed when the clock said 11:45pm and get up at 7:45am
   Unknown to ppts, the researchers sped the clocks up over the study to the point than an apparent 24 hour day was actually 22 hours
   11 of the ppts were unable to comfortably adjust to a 22 hour day, showing that we have a strong internal biological clock that cannot be easily overridden by zeitgebers

Question 88

Strengths of circadian rhythms

Answer 88

The main strengths of research into circadian rhythms are the number of practical applications it has had, such as:
1. Medical treatment (general circadian rhythm research)
2. Shift work (sleep-wake cycle research)
3. Shifting the school day (sleep-wake cycle)
Medical treatment:
Circadian rhythms research has been used to improve medical treatment, as research helps us understand how circadian rhythms co-ordinate a number of the body’s basic processes such as heart rate, digestion and hormone levels.
For example, the field of chronotherapeutics looks at how medical treatment can be administered in such a way that corresponds to a person’s biological treatments. Heart attacks are mostly likely to occur early in the morning (as blood clotting peaks in the morning), so taking aspirin last thing at night can reduce a risk of a heart attack (as aspirin reduces blood platelet activity) (Bonten et al, 2015)
This is a strength because it shows that circadian rhythm research can help increase the effectiveness of medical treatments by considering the timing of drug treatments

Shift work:
A second strength of research into circadian rhythms is that has helped us understand the adverse consequences thar occur when they are disrupted (desynchronisation)
For example, consider people working night shifts. They have to work when their body wants to sleep and they have to work sleep when their body wants to be awake. Night shift workers experience circadian trough with a period of reduced concentration at around 6am, meaning mistakes and accidents are most likely to occur (most lorry accidents occur between 4am and 7am). Research has also indicated that shift workers are three times more likely to develop heart disease compared to people who work typical working patterns. One suggestion has been to rotate shifts with the clock, i.e. a week of morning shifts, week afternoon shifts, then week of evening shifts then week night shifts and then back to morning shifts. Czeisler et al (1982) tested this in a chemical plant in Utah and found workers reported feeling better and less tired on the job and managers reported increased productivity and fewer errors. Night shift workers also have higher rates of mental healthy issues and divorce
This is a strength because it shows the circadian rhythm research has real-work health and economic productivity for shift workers
(Further research into desynchronisation has been carried out into jet lag. In jet lag, your body clock tells you it is one time but the external factors tell you it is a different time. This only occurs West to East (the worst) and East to West. People could use melatonin as a supplement to help them manage and reduce jet lag (the hormone that makes us sleepy). 1 2001 review looked at 10 studies in which people who were travelling used melatonin and were given it around the bed time of their new location. They reported significantly reduced jet lag)

Shifting the school day:
One strength of research into carcadian rhythms is that is has practical applications being able to be linked to the eduction system and the start times of schools
For example, research has shown that teenagers need more sleep than people of other age groups, for a number of reasons. Firstly, during puberty the brain undergoes reorganisation, as said by researcher Neil Stanley, and sleep gives us the opportunity to do thus. Not only do teenagers go through the experience of changes in the brain and body, but they are also experiencing many other factors in their life that lead them to require to sleep longer, such as exams, the transition from childhood and adulthood and functioning in this new life with less emotional support than they were initially provided with. All of this makes a lot of energy and is also very stressful, and seep is important for processes such as memory and learning, dealing with emotions and repair and recuperation. With all of these processes requiring sleep, it explains why teenagers need a lot more sleep than others and therefore we can adapt the eduction system so that teenagers are able to get this extra sleep
This is a strength because practical applications have emerged as a result of these research results. A few sixth form colleges have adapted the start time of their school day, starting at 10am, to allow their students longer to sleep in the morning so their body can undergo these processes, as well as improve their attention in lessons (reserach has shown that within our internal circadian rhythm, our peak attention time is 10am), allowing them to get the most out of their eduction

Question 89

Limiations of carcadian rhythms

Answer 89

One limitation of research into circadian rhythms is that generalisations are difficult to make
Cave and bunker studies are based on very small samples of ppts
Other research suggests that sleep-wake cycles vary much more widely than these findings might initially suggest
For example:
- Czeisler et al (1999) found individual differences in sleep-wake cycles varying from 13 to 65 hours
- Duffy et al (2001) found some people are ‘larks’ and others are ‘owls’
- Even Siffre (1999) observed that his own sleep-wake cycle had changed since he was a young man in the early 1960s
This is a limitation because it means it’s difficult to use the research data to discuss anything more than averages, which may be be meaningless, meaning that the practical applications that’s have been developed from such research may not be as useful or as practical as we might think or want them to be

Question 90

Endogenous pacemakers

Answer 90

The internal body clock
The sleep-wake cycle involves both the SCN and the pineal gland
- biological processes that control our biological rhythms
- included neural factors and hormones
It works as follows to create our circadian sleep-wake cycle:
1. The optic chiasm takes in information about the amount and quality of light taken in by the eye
2. This information travels along the optic nerve into the SCN
3. The SCN passes the information to the pineal gland
4. The pineal gland secretes melatonin in relation y to the amount of light there is
- There is a negative correlation here
- less light, more melatonin
5. Melatonin induces sleep
- levels rise from dusk and reach a critical level which makes us sleepy

Question 91

Supporting evidence

Answer 91

There is a large body of evidence form animal studies that demonstrated the influence of SCN (endogenous pacemaker) on the sleep-wake cycle
- we can generalise to humans because there are similar mechanisms in the mammalian brain here

DeCoursey et al (2000) chipmunk study
- 30 chipmunks had their SCN connections destroyed
- returned to their natural environment and observed for 80 days
- their sleep-wale cycle disappeared by the end of the 80days and a significant number had been killed by predators
- they were awake and out and about when their predators were awake and hunting

Ralph et al (1990) hamster study
- mutant hamsters with 20 hour sleep-wake cycles were bred (they had polyphasic sleep-wake cycles)
- SCN cells from foetal tissue of the mutant hamsters were transplanted into the brains of normal hamsters
- these hamsters then took on the 20 hour sleep-wake cycle, instead of their usual polyphasic sleep-wake cycle, because the SCN controls the sleep-wake cycle

Question 92

Strengths of endogenous pacemakers

Answer 92

Research studies are reliable and have been backed up by a range of other studies:
- Stephan & Sucker (1972) damaged the SCN in rats and found their sleep-ale cycle was disputed
- Morgan (1995) removed the SCN from hamsters and found their sleep-wake cycle disappeared. They also transplanted;anted SCN from mutant hamsters bred to have shorter cycles. Their sleep-wake cycle returned but was shorter
- Silver (1996) transplanted normal cells into hamsters bred to have mutant cycles and those who had had mutant SCN cells transplanted. They found normal polyphasic sleep-wake cycle returned
Also shows that these have good predictive validity

Question 93

Limitations of endogenous pacemakers

Answer 93

However, one limitation is that research into endogenous pacemakers in the sleep-wake cycle has predominantly focused on the SCN in the brain but thus might be at the cost of minimising or ignoring other biological clocks we have in other parts of our bodies
For example, until relatively recently, research that suggested the existence of circadian oscillators (biological clocks) in peripheral organs (e..g lungs, pancreas, skin) in mammals was largely dismissed. This was despite the fact there was increasing amount of research showing that these exist and that, while they are influence by the SCN, also act independently form it. For example, changing the feeding patterns of mice could alter the circadian rhythms in the liver by up to 12 hours while the rhythm of the SCN was unaffected
This is a limitation because it means we might be ignoring other complex influences on our circadian rhythms

Additionally, when studying the tole of endogenous pacemakers such as the SCN in our circadian rhythm sleep-wake cycle we cannot study these in isolation
Even in the (rare) cave and bunker studies, where researchers such as Siffre attempted to remove as many exogenous zeitgebers as they could, there were still some zeitgebers e.g. the artificial lights that Siffre used, and it is entirely possible that these could have reset his biological clock. It is clear that in everyday life there in an interactionist system here - our pacemakers and zeitgebers do interact
This is a limitation because it suggests that the more researchers attempt to isolate the influence of internal pacemakers, the lower the validity of the research

Question 94

Exogenous Zeitgebers

Answer 94

As we have seen, light is the key exogenous zeitgeber in our sleep wake cycle
We can even recieve information about light from other parts of our body other than sour eyes
Campbell and Murphy (1998) shows that light can be detected by skin receptors - they woke up 15 ppts at various times and each time they woke them, the shone a light pad on the back of their knees
This changed their usual sleep-wake cycle by up to 3 hours

The role of light being the main zeitgebers is supported by case study research
For example, Miles et al (1977) documented the circadian rhythms of a man who has been bribed since birth
He had a strong 24.9 hour sleep-wake y cycle despite the fact he was exposed to other exogenous zeitgebers such as clocks, alarms and radios
He struggled to set his body to a 24 hour cycle so much that he had to use sedatives to sleep and stimulants in the morning to co-ordinate his sleep-wake cycle with that of the world around him
This is strong evidence is the key exogenous factor in sleep-wake cycle, as it was the only exogenous ziethgeber he lacked

However, light can’t be the only exogenous zeitgeber
For example, people in the artic circle lie in a world of endless days in summer and endless night is winter, yet they are able to maintain a fairly regular sleep wake cycle
This suggests that our sleep-wake cycle is primarily controlled by endogenous pacemakers than can override environmental changes in light

Or it might suggest that there other other exogenous zeitgebers other than light that help people t maintain theirt circadian sleep-wake cycle, such as social cues e.g. meal times
This can be seen in new Born babies who have random sleep-week cycles when they are born
- circadian rhythms start to emerge about 6 weeks
Within 10 weeks from this point, a baby’s circadian rhythm is pretty munch in line with parental schedules, including adult-determined mealtimes and bedtimes

We can also see the effect of socials cues when dealing with jet lag
This is caused by our internal body clock being out of sync with the external world, and it can have a negative impact on Alertness and performance
An effect way of dealing with thus us to immediately adopt (even as soon as you get off the lane) to local times for eating and sleeping and ignoring your own internal feelings as much as you can