Biopsychology Flashcards
1
Q
What does the nervous system consist of?
A
The brain and spinal cord.
2
Q
What is the two main functions of the nervous system?
A
- To collect, process and respond to environmental information
- To co-ordinate the working of different organs and cells in the body.
3
Q
What two main subsystems is the nervous system divided into?
A
- The central nervous system (CNS)
- The peripheral nervous system (PNS)
4
Q
What is the brains outer layer called?
A
The cerebral cortex
5
Q
How thick is the cerebral cortex?
A
3mm thick.
6
Q
True or false: the cerebral cortex is only found in mammals
A
True!
The brain is highly developed in humans and distinguishes our higher mental functions from those of other animals.
Creatures such as jellyfish and sponges do not have a brain.
7
Q
What is the brain divided into?
A
Two hemispheres
8
Q
What is the spinal cord?
A
An extension of the brain
9
Q
What is the spinal cord responsible for?
A
- Passes messages to and from the brain
- Connects nerves to the PNS
- Responsible for reflex actions
10
Q
What are the subdivisions of the peripheral nervous system?
A
- The autonomic nervous system
- The somatic nervous system
11
Q
What is the central nervous system?
A
Consists of the brain and spinal cord and is the origin of all complex commands and decisions.
12
Q
What does the PNS do?
A
Sends information to the CNS from the outside world, and transmits messages from the CNS to muscles and glands in the body.
13
Q
What does the somatic nervous system do?
A
Governs muscle movement and receives information from sensory receptors
14
Q
What does the autonomic nervous system do?
A
Governs vital functions in the body such as breathing, heart rate, digestion and stress responses: this operates involuntarily and is subdivided into the sympathetic and parasympathetic NS.
15
Q
What is the autonomic nervous system subdivided into?
A
- Parasympathetic nervous system
- Sympathetic nervous system
16
Q
What is the endocrine system made of?
A
Glands and hormones
17
Q
What is the master gland?
A
The pituitary gland: it controls the release of hormones from all the endocrine glands in the body
18
Q
What is the difference between the endocrine system and the nervous system?
A
The endocrine system acts more slowly than the nervous system but has very widespread and powerful effects
19
Q
What is the autonomic nervous system?
A
A subdivision of the peripheral nervous system that transmits information to and from internal organs. It is ‘autonomic’ as it is INVOLUNTARY.
It governs vital functions in the body such as breathing, heart rate and digestion.
20
Q
What is the somatic nervous system?
A
The subdivision of the PNS that governs VOLUNTARY muscle movement and receives information from sensory receptors.
21
Q
What does the endocrine system consist of?
A
Consists of glands that produce hormones which are secreted into the blood stream.
22
Q
What is the ‘master gland’ and what does it do?
A
The pituitary gland.
It controls the release of hormones from all the other endocrine glands in the body.
23
Q
Name two hormones and their effect on the body
A
- Thyroxine: can affect both cells in the heart and also effects cells throughout the body through increasing basal metabolic rate - affecting growth.
- Adrenaline: released from adrenal glands, triggers the fight or flight response.
24
Q
What happens when someone is scared?
A
- The hypothalamus activates the pituitary gland.
- The pituitary gland then triggers activity in the SYMPATHETIC branch of the autonomic nervous system.
- From this, the ANS changes from its normal resting state (the PARASYMPATHETIC nervous system) to the physiologically aroused SYMPATHETIC state.
25
Outline the fight or flight response.
1) The stress hormone adrenaline is released from the adrenal medulla - this triggers physiological changes such as increased heart and breathing rate and pupil dilation.
This release of adrenaline brings about the physiological arousal necessary for the fight or flight response.
2) This happens INSTANTLY when the threat is detected.
It is an acute response and autonomic in the body: bringing about physiological change
3) Once the threat has passed, the parasympathetic nervous system returns the body to it's resting state. The parasympathetic branch of the ANS works in opposition to the sympathetic nervous system, being called ANTAGONISTIC.
It works as a 'brake' to reduce the activities of the body that were enhanced by the actions of the sympathetic branch.
Called: 'rest and digest'.
26
Briefly evaluate the nervous and endocrine system (basically fight or flight)
- Simplification of 'fight or flight'
The reaction is not limited to 'fight or flight', some psychologists argue that humans engage in an initial freeze response. A psychologist suggested the first response to danger is to avoid confrontation all together, demonstrated by 'freeze'. During the freeze, animals and humans are hypervigilant while they analyze the next course of action.
- Androcentric theory
Research into the fight or flight response was typically conducted on males, meaning the findings were generalized to females.
Recent research suggests females can resort to a 'tend and befriend' response. Taylor et al. believes that they will protect their offspring (tend) and form alliances (befriend) rather than fight an adversary or flee.
This means there is a beta bias within this area of research.
- Lack of modern use.
For our ancestors, fight or flight acted as a useful survival mechanism to respond to predators. It can be argued that modern life rarely requires such an intense biological response. From this, the stressors of modern day life can activate the fight or flight response, having negative consequences on health such as blood pressure increase. This means that the FF response in maladaptive in the modern day.
27
What is a neuron?
A nerve cell that processes and transmits messages through electrical and chemical signals.
28
What does a sensory neuron do AND what is it's structure?
- Carries messages from the PNS to the CNS.
- Structure: Long dendrites and short axons.
29
What does a relay neuron do AND what is it's structure?
- Connect the sensory neurons to the motor or other relay neurons.
- Structure: Short dendrites and short axons.
30
What does a motor neuron do AND what is it's structure?
- Connect the CNS to effectors such as muscles and glands.
- Structure: Short dendrites and long axons.
31
Write the structure of a neuron.
- All neurons have a cell body (soma) which includes the nucleus - containing the genetic information.
- Branch like structures called dendrites protrude from the cell body - these carry electrical impulses from neighboring neurons TOWARD the cell body.
- The axon carries the impulses away from the cell body down the length of the neuron.
- The axon is covered by a fatty myelin sheath layer that protects and insulates the axon whilst speeding up electrical transmission of the impulse.
- Nodes of Ranvier is where the myelin sheath is segmented (there are gaps) so transmission can be sped up by forcing it to 'jump' across gaps along the axon.
- At the end of the axon are TERMINAL BUTTONS that communicate with the next neuron in the chain across the synapse gap.
32
What is the difference between axons and dendrites?
Axons take signals TO the synapse, dendrites take signals AWAY from the synapse (to the cell body)
33
How does action potential occur?
Neurons, in resting state, are negatively charged compared to their outside.
When a neuron is activated by a stimulus, the inside of the cell becomes POSITIVELY charged temporarily - causing an ACTION POTENTIAL to occur.
This creates an electrical impulse that travels down the axon towards the end of the neuron.
34
How do neurons communicate with each other?
They communicate within groups called neural networks.
35
What does the synapse consist of?
Both the space between two neurons (the synaptic cleft) as well as the presynaptic terminal and post synaptic receptor sites.
36
What is the difference between signal transmittance WITHIN the neuron vs BETWEEN neurons?
Signals WITHIN the neuron are transmitted electrically.
Signals BETWEEN neurons are transmitted chemically by SYNAPTIC TRANSMISSION.
37
What happens when an electrical impulse reaches the end of a neuron?
It triggers the release of neurotransmitters from tiny sacs called synaptic vesicles.
38
Outline the process of synaptic transmission.
1) When an electrical signal reaches the presynaptic terminal (end of the neuron) it causes the release of synaptic vesicles which carry neurotransmitters.
2) Once the neurotransmitters within the synaptic vesicles cross the synapse they bind to post-synaptic receptor sites on the dendrites of the next neuron. These receptors (of course) are complimentary in shape to the neurotransmitters.
3) The neurotransmitter is converted back into an electrical message to transmit through the post-synaptic neuron. The process then repeats.
4) Excitation and inhibition effect
5) SUMMATION - very important !!!
39
What is excitation and inhibition?
- Excitation increases the positive charge of the post-synaptic neuron, INCREASING the likelihood of the neuron firing and passing on an electrical impulse (e.g adrenaline)
- Inhibition increases the negative charge of the post-synaptic neuron, DECREASING the likelihood of a neuron firing and passing on an electrical impulse (e.g- serotonin)
40
What is summation and what does it do and outline the process.
Summation decides whether the a post-synaptic neuron fires.
In summation, the excitatory and inhibitory effects are 'summed'
If the overall effect in inhibitory, the neuron is less likely to fire
If the overall effect is excitatory, the neuron is more likely to fire.
Therefore, the action potential of the post-synaptic neuron is only triggered if the sum of the excitatory and inhibitory signals reach a certain threshold.
! For a neuron to fire or not, a certain excitatory or inhibitory effect threshold must be met.
41
What is localization of function theory?
The theory that different areas of the brain are responsible for different behaviors, processes or activities.
42
Who pioneered localization theory?
Paul Broca and Karl Wernicke.
43
What is the opposite of localization of function theory?
Holistic theory - the idea that ALL parts of the brain were involved in the processing of thought and action.
44
What is another word for localization theory?
Cortical specialization.
45
What is lateralization?
Where some of our physical and psychological functions are controlled or dominated by a particular hemisphere (either right or left hemisphere)
46
True or false: Activity on the left-hand side of the body is controlled by the right hemisphere and vice-versa.
TRUE!
This is called cross-wiring.
47
Name the 4 lobes in the brain.
- The frontal lobe
- The parietal lobe
- The occipital lobe
- The temporal lobe
48
Where is the motor area located?
The back of the frontal lobe (in BOTH hemispheres).
49
What is the motor areas function and what would damage to the area do?
- Function: Controls voluntary movement on opposite sides of the body.
- Damage: Loss of control over fine movement regulation.
50
Where is the somatosensory area located?
At the front of both parietal lobes
(Separated from the motor area by the central sulcus valley)
51
What is the somatosensory areas function and what would damage to the area do?
- Function: Where sensory information from the skin is represented.
(The amount of the somatosensory area devoted to a particular body part denotes it's sensitivity: the hand and face receptors occupy over half of this area)
- Damage: Sensitivity.
52
Where is the visual area?
In the occipital lobe at the back of the brain.
53
What is the visual areas function and what would damage to the area do?
- Function: Each eye sends information from the right visual field to the left visual CORTEX, and information from the left visual field to the right visual CORTEX.
- Damage: For example, damage to the left hemisphere can produce blindness in the part of the right visual field in both eyes and vice-versa.
54
Where is the auditory area?
In the temporal lobes (on the side of the brain)
55
What is the auditory areas function and what would damage to the area do?
- Function: Analyses speech based information.
- Damage: Partial hearing loss.
56
What areas are the language centers of the brain?
- Wernicke's area
- Broca's area
57
Where is the Broca's area?
In the LEFT frontal lobe
58
What is Broca's area responsible for and what does damage to the area cause?
- Responsible for speech production.
- Damage to the area causes Broca's aphasia - this is characterized by slow, labored speech that is lacking in fluency.
(For example, Broca's patient Tan could only say the word 'Tan' - In addition, they struggle with predispositions and conjunctives)
59
Where is Wernicke's area?
In the LEFT temporal lobe.
60
What is Wernicke's area responsible for and what does damage to the area cause?
- Responsible for language comprehension / understanding.
- Damage to the area causes Wernicke's aphasia - characterized by having no problems producing language but severe difficulty understanding it: they produce nonsense words (NEOLOGISMS)
61
What is the difference between Broca's aphasia and Wernicke's aphasia?
- In Broca's aphasia, the patients have no issue comprehending language but struggle to produce language.
- In Wernicke's aphasia, the patients are able to produce language, yet lack language comprehension.
62
Evaluate Localization of function in the brain.
- Evidence from neurosurgery
Damage to brain areas have been linked to mental disorders. Neurosurgery for mental illness exists as a last resort treatment, with a cingulotomy being a common surgery. A cingulotomy involves isolating a region called the cingulate gyrus which is implicated in OCD. Dougherty et al. followed up 44 people with this disorder who had the operation. After 32 weeks, 30% had met the criteria for a successful response to surgery. The relative success of these procedures suggest that behaviors associated with disorders may be localized to sections of the brain.
- Evidence from brain scans
Brain scans support localization theory. Petersen (like in memory topic!) had used scans to demonstrate how Broca's area was active during reading tasks and Wernicke's area was active during listening tasks.
In addition, Petersen also contributed to scan studies showing how episodic and semantic memory reside in different areas of the prefrontal cortex. This means objective methods for measuring brain activity have provided evidence that many brain functions are localized.
- Counter-evidence.
Karl Lashley had removed 10-50% of rats cortexes who were learning to navigate a maze. In this, no area was proven to be more important than the other in terms of the rats ability to find a route through the maze. The learning process appeared to require every part of the cortex rather than one specific area. This suggests that higher cognitive processes, such as learning, are not localized but distributed more holistically.
- Case study criticism (GAGE)
Case studies of neurological damage support localization theory but only to a certain extent. There are limitations in terms of how it is difficult to make meaningful generalizations on findings from single individuals and it is inappropriate to make inferences on what they were like before damage.
63
What is meant by brain plasticity?
Plasticity is the brains tendency to change and adapt as a result of new experience and learning - often involving the growth of new connections.
64
What is meant by functional recovery?
Functional recovery is a form of plasticity following damage or trauma.
It is the brains ability to redistribute or transfer function - usually performed by a damaged area to other undamaged areas.
65
What happens during infancy in terms of plasticity?
During infancy, the brain experiences rapid growth in the number of synaptic connections it has - peaking at around 15000 per neuron at 2-3 years old.
66
What is synaptic pruning?
The idea that, as we age, rarely used connections are erased and frequently used pathways are strengthened by synaptic pruning.
This allows lifelong plasticity where neural connections are formed in response to new demands on the brain.
67
Outline research into plasticity
- MAGUIRE ET AL.
- Found that the brains of London taxi drivers had significantly more volume of grey matter in the POSTERIOR HIPPOCAMPUS compared to a control group.
(the POSTERIOR HIPPOCAMPUS is involved in the development of spatial and navigational skills)
1) As part of training London taxi drivers must take a complex test called 'the knowledge' where they are expected to recall city streets and possible routes - Maguire found that this alters the structure of the taxi drivers brains.
2) Findings also showed that there was a positive correlation between time in job and how pronounced the structural difference was.
68
Outline Draganski's research into plasticity.
Draganski imaged brains of medical students three months before and after their final exams.
Learning induced changes were seen to have occurred in the posterior hippocampus and the parietal cortex - presumably as a result of learning.
69
How does functional recovery work after brain trauma?
Unaffected areas are able to adapt and compensate for damaged areas - the healthy brain will take over the function of destroyed, damaged or missing areas.
70
What is spontaneous recovery and what happens during it?
Spontaneous recovery is where functional recovery occurs quickly following trauma.
After the following 7 weeks it slows down, and this is when the individual may require rehabilitation to further recover.
71
Name 3 processes involved in recovery.
- Axonal sprouting
- Denervation super-sensitivity
- Recruitment of homologous (similar) areas.
72
What is axonal sprouting in functional recovery?
The growth of new nerve endings which connect to other undamaged nerve cells to form new neuronal pathways.
73
What is denervation super-sensitivity in functional recovery?
When axons become aroused to a higher level to COMPENSATE for those damaged or lost. This can create negative consequences such as hypersensitivity to pain.
74
What is recruitment of homologous areas in functional recovery?
Similar areas are recruited on the opposite side of the brain to the damaged area to allow specific tasks to still be performed.
For example, if Broca's area was damaged, the right-sided equivalent would carry out its functions until functionality may shift back to the left.
75
Evaluate plasticity and functional recovery of the brain.
- Age and plasticity.
It was originally thought that functional plasticity reduces with age, however there is research evidence to contest this. Bezzola studied participants aged 40-60 who had undergone 40 hours of golf training.
The result of fMRI scans showed decreased activity in the MOTOR CORTEX compared to a control group - this means that neural representations were enhanced following training. This demonstrates how neural plasticity can continue into later life.
- Negative plasticity.
Plasticity in the brain is not always a positive attribute - having negative consequences. Research has found that prolonged drug use results in lower cognitive functioning and risk of dementia in later life. Even more notably, 60-80% of amputees experience phantom limb syndrome, experiencing painful sensations in the space the missing limb would be. This is due to cortical reorganization in the somatosensory cortex when a limb is lost.
- Practical application.
Research into brain plasticity and functional recovery has real-world applications towards NEUROREHABILITATION programs. Following trauma, spontaneous recovery tends to slow down after a number of weeks so therapies may be necessary to maintain improvements. Techniques developed from this study include: movement therapy and electrical stimulation of the brain to counter motor or cognitive deficits. This implies that, although spontaneous recovery may have the capacity to 'fix' the brain, intervention exists to further recovery.
- COGNITIVE RESERVES
There is evidence for functional recovery that suggests that educational attainment may have an effect on how the brain adapts to injury. Research has shown that people who had spent a longer time in education, therefore having a larger cognitive reserve, had a better chance at disability-free recovery (DFR). 2/5 of those who had spent 16 years in education reached DFR compared to 10% of those who had spent 12 years in education. This shows how environmental aspects in development can impact how efficient brain plasticity is.
76
What is hemispheric lateralization?
The idea that the two hemispheres of the brain are functionally different and that certain mental processes and behaviors are dominated by one hemisphere rather than the other.
For example, the left hemisphere dominates language.
77
What is split-brain research?
Studies on epileptic patients who had undergone surgical treatment of a COMMISSUROTOMY - where the corpus callosum that holds the brain together is severed to separate the two hemispheres.
78
What did split brain research enable researchers to do?
Investigate / test lateral functions of the brain hemispheres in isolation.
Allowed them to see the extent to which the two hemispheres were specialized for certain functions and whether they performed tasks independently of one another.
79
Who was the psychologist who studied the split brain?
Roger Sperry.
80
Is language lateralized?
YES
The two main centers of language are in the left hemisphere.
The right hemisphere can only produce rudimentary words and phrases but contributes to the emotional context of what is said.
81
What is the left hemisphere and the right hemisphere described as (separate)
- Left hemisphere: analyzer.
- Right hemisphere: synthesizer.
82
Which functions in the brain are not lateralized?
The visual, motor and somatosensory areas appear in both hemispheres, therefore they are not lateralized.
83
What is meant by contralateral wiring in the motor area?
The motor area in the brain is CROSSWIRED - this means that the right hemisphere controls movement on the left hand side of the body and the left hemisphere controls movement on the right hand side of the body.
84
How is vision wired?
- Both contralaterally and ipsilaterally. (opposite and same sided)
85
Explain how vision is wired.
- Contralaterally and ipsilaterally (opposite and same sided).
- Each eye receives light from the left visual field (LVF) and right visual field (RVF)
- The LVF of both eyes is connected to the right hemisphere and the RVF of both eyes is connected to the left hemisphere
- This enables the visual areas to compare different perspectives from both eyes for depth perception.
86
Evaluate hemispheric lateralization briefly.
- Lateralization in the connected brain.
Research shows that even in CONNECTED brains, the two hemispheres process information differently. A psychologist used PET scans to identify which brain areas were active during a visual processing task. Connected brain participants were asked to look at global elements of an image (looking at a whole forest) the right hemisphere was more active. When required to focus on finer detail (a singular tree) areas of the left hemisphere tended to dominate.
This suggests that, as far as visual processing is concerned, hemispheric lateralization is a feature of the connected brain as well as the split brain.
- Counterevidence to roles of hemispheres.
A limitation is that the idea that the LH takes the role of the analyzer and the RH, the synthesizer may be wrong. Although there may be different functions for the LH and RH, research suggests that people do not have a dominant side of their brain that produces a perceived personality. In an analysis of over 1000 7-29 year old participants, it was found that people used certain hemispheres for certain tasks - proving lateralization. Despite this, there was no evidence of a dominant side. This suggests that the lateralization theory that people are 'left or right brained' is incorrect.
87
Why did epileptic people have a commissurotomy?
During epileptic seizures the brain experiences excessive electrical activity which travels between hemispheres - severing the corpus callosum reduces this.
88
What was Sperry's procedure in split brain research?
!!!
The general procedure was that an image would be projected to a patients right visual field (processed by the left hemisphere) and vice-versa using same or different images.
In an intact brain, the corpus callosum would share the information between both hemispheres to provide a complete picture of the visual world. In split-brain patients, however, presenting information to one hemisphere meant that information could not be conveyed to the opposite hemisphere.
89
What are 3 tasks Sperry investigated under split brain?
- Describing what they saw
- Touch recognition
- Drawing tasks
90
What were the key findings in 'describing what was seen'
- Split-brain patients could easily describe and name objects or words that were shown to their right visual field: this is because the their left hemisphere is responsible for language production.
- Objects or words shown to the left visual field were not able to be recalled verbally, with the patients claiming they did not see anything: this is because the language center is NOT located in the right hemisphere where the LVF is processed, meaning that information cannot be relayed to the LH.
91
What was the drawing task procedure and what were the findings?
- Procedure: the patients were presented an image in either their left or right visual field and asked to draw an accurate image matching it.
- When the image was shown to their LEFT visual field (processed by right hemisphere) the patients could draw an accurate image that matched it despite claiming that they didn't see anything, when drawing with their left hand.
- When the image was shown to their RIGHT visual field (processed by the left hemisphere) they were much less able to draw what they had seen with their right hand - this was the case in ALL split brain participants despite the fact that they were all right handed. This is because the left hemisphere is concerned with language processing.
92
What was touch recognition task procedure and what were the findings?
- Procedure: Objects were flashed on either visual field and the patient was expected to describe what they had seen verbally and select a matching object from a grab bag that was hidden behind a screen.
- When the image was flashed to the LEFT visual field, they could not attach verbal labels to the image - however, they were able to select a matching object from a bag of different objects using their LEFT HAND (linked to right hemisphere)
- The left hand was able to select an object most closely related to the one flashed to their LVF (for example, matching an ash tray to a cigarette). This meant that the patient was not able to verbally identify what they had seen but could 'understand' what the object was using their right hemisphere to select corresponding objects accordingly.
93
Evaluate split-brain research.
- Research support
There is support from more recent split-brain research.
Gazzaniga demonstrated how split-brain patients actually performed better than those with an intact corpus callosum on certain tasks.
For example, they were faster at identifying 'odd-ones out' in an array of similar objects compared to normal brained participants.
In the intact brain, the left hemispheres better cognitive strategies are 'watered down' by the inferior right hemisphere. This supports Sperry's claim that the left and right hemisphere are distinct.
- Generalization issues
Sperry's research is limited in the sense that casual relationships are hard to establish. In the study, split-brain participants were compared to neurotypical patients control group. None of the control group participants had epilepsy, introducing a major confounding variable. Any differences observed between the two groups may have been a result of epilepsy rather than the split brain. This indicates that some unique cognitive abilities in split-brained patients may have been due to epilepsy as well as their corpus callosum.
- Ethics.
A strength is that ethics involved in this research are relatively stable. The commissurotomy was not performed for the purpose of research intention. So, Sperry's participants were not deliberately harmed. In addition, all procedures were explained to the split-brain participants and their full informed consent was gained.
94
What are the 4 ways of studying the brain in biopsychology?
- fMRI
- EEG
- ERP
- Post mortem.
95
What does fMRI stand for?
Functional magnetic resonance imaging.
96
What does EEG stand for?
Electroencephalogram.
97
What does ERP stand for?
Event related potentials.
98
How does an fMRI work?
It detects changes in blood oxygenation and flow that occur as a result of neural activity in specific parts of the brain.
When a brain area is active during a task it consumes more oxygen, the blood meets this demand by directing flow to the active area (the HAEMODYNAMIC RESPONSE).
99
What is an fMRI?
A method of brain scanning used to measure brain activity while a person is performing a task using MRI technology.
100
What does fMRI produce?
3D images (activation maps) that shows which parts of the brain are involved in particular mental processes - helping understand LOCALIZATION.
101
Evaluate the strengths and weaknesses of fMRI
- Does not rely on radiation
Unlike other scanning techniques such as PET scans, if administered correctly, fMRI's are virtually risk free, non-invasive and straightforward to use.
- High spatial resolution.
fMRI produces images with high spatial resolution, this means it depicts detail by millimeter, providing a clear and precise image of how activity is localized.
- Poor temporal resolution.
fMRI has a 5-second lag time behind the image on screen and initial firing of neuronal activity - this means it cannot fully represent moment-to-moment brain activity.
- Limited measuring
fMRI can only measure blood flow in the brain, not being able to actually hone in on the activity of individual neurons so it can be difficult to interpret what kind of brain activity is being represented.
102
What is an electroencephalogram?
An ECG is a record of tiny electrical impulses produced by the brains activity. By measuring characteristics of wave patterns, it is a diagnostic tool to detect ARRHYTHMIC patterns of activity that could indicate conditions like epilepsy or tumors.
103
How to EEGs work?
They measure electrical activity within the brain via electrodes fixed to an individuals scalp using a skull cap.
It then records patterns generated by millions of neurons to provide an overall account of brain activity.
104
Evaluate the strengths and limitations of EEG's.
- Valuable for diagnostic purpose.
EEGs are valuable for the diagnosis of conditions such as epilepsy, characterized by random bursts of electrical activity. Furthermore, it has contributed to the study of sleep stages.
- High temporal resolution
Unlike fMRI's, EEGs have high temporal resolution - it accurately detects activity at a resolution of a single millisecond.
- Generalized results.
The information received is generalized as it is from many thousands of neurons - creating a large picture rather than one of spatial resolution. It is not useful, therefore, for pinpointing the exact source of neural activity.
Furthermore, it doesn't allow researchers to distinguish between activities originating in different but adjacent locations due to low spatial resolution.
105
What are event related potentials (ERP)
The brains electrophysiological response to a specific sensory, cognitive or motor event that is ISOLATED through statistical analysis of EEG data.
106
What does ERPs allow?
Allows the raw and crude form of data from EEGs to be interpreted through statistical averaging technique.
107
What occurs in ERPs?
Through statistical averaging techniques, extraneous brain activity from the original EEG recording is filtered out to leave only responses that relate to what the scientist is studying (for example: performance of a specific task).
This leaves event-related potentials: types of brainwaves triggered by specific events.
108
Evaluate the strengths and weaknesses of ERPs
- More specificity
Compared to EEG data, ERPs bring more specificity to the measurement of neural processes that would have been unmeasurable using only raw EEG data.
- High temporal resolution
ERP has high temporal resolution compared to fMRI, leading to widespread usage in the measurement of cognitive function and deficit. This has helped researchers to identify different types of ERP including allocating attention and maintaining working memory.
- Lack of standardization
ERPs can be criticized in the sense that there is a lack of standardization between different research studies which makes confirming findings difficult.
- Action of extraneous variables
In order to establish pure ERP data, background noise and extraneous variables must be eliminated completely - which is not easy to achieve.
109
What is a post-mortem examination?
Analyzing the brain after death to determine whether certain observed behavior or diagnosis during the patients lifetime is linked to certain abnormalities in brain structure.
110
Evaluate the strengths and weaknesses of post-mortem examinations
- Provided a foundation
Post mortem evidence was vital in providing a foundation for early understanding of key processes in the brain. Broca and Wernicke, for example, relied on post mortem evidence to establish the link between language, brain and behavior before imaging existed.
In HMs case, post mortem identified areas of damage associated to his memory deficits, helping to provide new and useful information
- Causation limited
Causation poses a significant issue for post mortem examinations as observed damage to the brain may not be linked to the issue under review, instead it could be unrelated trauma or decay.
- Ethics
Ethical issues arise with post-mortem examinations - the patient may have not been able to provide informed consent, such as HM who was unable to form new memories and therefore could not fully consent.
111
What is the definition of 'biological rhythms'
Distinct patterns of changes in body activity that conform to cyclical time periods.
112
What is a circadian rhythm?
A biological rhythm that is subject to a 24-hour cycle, regulating body processes such as the sleep-wake cycle and changes in core body temperature.
113
What two things are biological rhythms governed by?
- Endogenous pacemakers
- Exogenous zeitgebers
114
What affects the sleep/wake cycle?
- The exogenous zeitgeber of light
- The endogenous pacemaker: the suprachiasmatic nucleus.
115
Who conducted the cave study to investigate the effect of light on the sleep/wake cycle?
Michael Siffre
116
What was the procedure and findings of Siffre's cave study?
- Procedure: Siffre carried out his first cave study in mid-July for 2 months, being deprived of exposure to natural light and sound.
- Findings: Siffre resurfaced after 2 months and believed it was mid-August when it was mid-September. His 'free-running' biological rhythm settled down to one just above the 24-hour usual rhythm, though he continued to fall asleep and wake up on a regular schedule.
- This shows that without exogenous zeitgebers, we'd still have a sleep/wake cycle of around 24-hours (Siffre had 25)
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Who carried out the bunker study?
Aschoff and Wever.
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Outline Aschoff and Wever bunker study on the sleep/wake cycle.
Aschoff and Wever reports similar results to what was found in Siffre's study.
- Procedure: A group of participants were convinced to spent 4 weeks in a WW2 bunker deprived of natural light.
- Findings: all but 1 participant (who's sleep wake cycle extended to 29 hours) displayed a circadian rhythm of around 24-25 hours.
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What does Aschoff and Wever's bunker and Siffre's cave study tell us about the sleep/wake cycle?
Both studies suggest that the 'natural' sleep/wake cycle may be longer than 24-hours but it is entrained by exogenous zeitgebers associated with the 24-hour say (number of daylight hours)
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What study goes against Siffre and Aschoff and Wever's studies on circadian sleep/wake cycles?
Folkard et al. cave time manipulation study.
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Outline Folkard's cave study and what it tells us
- Procedure: 12 participants agreed to live in a dark cave for 3 weeks, retiring to bed when the clock said 11:45pm and rising at 7:45am. Over the course of the study, researchers gradually increased the speed of the clock without their knowledge until the 24 hour day lasted 22 hours.
- Findings: only one participant was able to comfortably adjust to the new regime.
- This tells us that the internal free-running circadian rhythm cannot be easily overrun by exogenous zeitgebers - we should not overestimate the impact of exogenous zeitgebers.
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Evaluate circadian rhythms.
- Practical application to shiftwork.
Knowledge of circadian rhythms provides an understanding of the adverse consequences that occur when the sleep/wake cycle is desynchronized. Night-shift workers experience a period of reduced concentration at around 6 in the morning - leading to more mistakes and accidents which could be detrimental medically. Research has also indicated that desynchronization can bring about poor health as night-shift workers are 3x more likely to experience heart disease than normal. This shows research has economic implications on how to best manage productivity.
- Generalization issues
Based on existing research, generalizations are hard to make as studies, such as Siffre's was conducted on a small participant sample. This means case-studies may not be representative of the whole population. Siffre confirmed this as in his most recent cave experience, Siffre noted that with aging his internal clock slowed down. This illustrates that factors can intervene in generalization preventing general conclusions being drawn.
- Individual differences
Further complicating generalizations, individual cycles may vary. Research suggests that sleep cycles can vary from 13-65 hours. In addition, studies show natural preferences play a role such as favoring going to bed early and rising early and vice-versa.
- Medical treatment practicality
Research into circadian rhythms proves useful in improving medical treatment. As circadian rhythms regulate processes such as digestion, heart rate and hormone levels that rise and fall daily medical treatments are administered in ways that correspond to this. Understanding of circadian rhythms has contributed to the field of pharmacokinetics - this is why people take aspirin at night as heart attacks are most common in the morning. This increases the efficiency of drugs.
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What is an infradian rhythm?
A biological rhythm with a frequency of less than one cycle per 24 hours, such as menstruation and seasonal affective disorder.
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What is an ultradian rhythm?
A biological rhythm with a frequency of more than one cycle per 24 hours, such as the individual stages of sleep.
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Outline how the menstrual cycle is an example of an infradian rhythm
The menstrual cycle is governed by monthly changes in hormone levels that regulate ovulation (release of an egg).
The cycle refers to the time between the first day of the period to the day before her next period, taking around 28 days to complete (24-35 days).
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Who carried out a study on the menstrual cycle being affected by exogenous factors (pheromones).
Stern and McClintock.
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Outline Stern and McClintock's procedure and findings on their menstrual cycle study
- Procedure: 29 women with a medical history of irregular periods were gathered as a sample. Samples of pheromones were gathered from 9/20 women at different stages in the menstrual cycle via cotton wool pads placed on their armpits for 8 hours. The cotton wool pads were then sterilized and frozen, to be rubbed on the upper lip of the other participants. On day one, pads from the first day of the menstrual cycle were applied to all 20 women, then the second day for the next day and so forth.
- Findings: 68% experienced changes to their menstrual cycle which brought them closer to their 'odor donor' This shows that the infradian menstrual cycle is regulated by both hormones as endogenous pacemakers yet are also impacted by the exogenous zeitgeber of pheromones.
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What type of rhythms is seasonal affective disorder?
Infradian and circannual.
(Circannual is a rhythm subject to a yearly cycle)
It is argued that it can be due to circadian rhythms as the symptoms can be due to disruption in the sleep wake cycle.
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What is seasonal affective disorder?
A depressive disorder with symptoms triggered during the winter months when the number of day hours shorten.
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How does the sleep/wake cycle influence SAD?
Melatonin.
The hormone melatonin may be involved with SAD - during the night the PINEAL gland secretes melatonin until dawn where there is an increase in light. Prolonged lack of light will prolong this process which is believed to interfere with serotonin production.
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Evaluate infradian rhythms
- Evolutionary basis
One strength of menstrual synchrony as an infradian rhythm is that it can be explained on an evolutionary basis. Synchronization of the menstrual cycle, as seen in Stern and McClintock's study has biological value. For ancestors, it was advantageous for women to menstruate together which allowed them to become pregnant at similar times. In a social group, this allowed babies who had lost their mother to gain access to breastmilk - improving survival. This implies that this infradian rhythm is an adaptive strategy.
- Methodological limitations.
Studies into menstrual synchronization are limited in the sense that confounding variables may interact with findings. There are many factors that affect change to the menstrual cycle including stress, diet and weight. These act as confounding variables - meaning any supposed change to pattern of synchronization is no more than would have been expected to occur by chance. This suggests that menstrual cycle studies are restricted in validity.
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Give an example of an ultradian rhythm
The stages of sleep - the sleep cycle.
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How many distinct stages of sleep are there?
5 distinct stages.
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How long does each sleep stage span in the sleep cycle?
90 mins.
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Describe stages 1 and 2 of the sleep cycle.
- Light sleep where the person can be easily woken
- Brainwave patterns become more slow and rhythmic (ALPHA WAVES)
- In stage 2, they become slower as the sleep deepens (THETA WAVES)
- Occasionally there are random changes in pattern known as sleep spindles.
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Describe stages 3 and 4 of the sleep cycle.
SLOW WAVE SLEEP
- Difficult to wake someone in these stages
- DELTA WAVES create a slower and greater amplitude.
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Describe stage 5 of the sleep cycle
REM SLEEP (rapid eye movement)
- Body is paralyzed, brain activity speeds up and resembles the awake brain.
- Dreams are most often experienced here.
- The brain has theta waves.
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Evaluate ultradian rhythms
- Improved understanding
One strength of research into ultradian rhythms is that it has improved sleep related changes in sleep.
Sleep scientists found that stages 3-4 (slow wave sleep) is associated with growth hormone production, therefore it reduces with age.
According to research, sleep deficit may explain various issues in old age such as reduced alertness. In order to increase SWS, treatments such as relaxation may be used. This means that ultradian knowledge has practical value.
- Individual differences
One limitation of ultradian rhythms is the significant variation between people. Tucker et al. found large differences between participants in terms of sleep cycle stage duration, especially in slow wave sleep (3-4). It has been suggested that these differences are likely to be biologically determined. This makes it difficult to describe 'normal' sleep in any meaningful way.
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Define endogenous pacemakers
Internal body clocks that can regulate biological rhythms (such as the influence of the suprachiasmatic nucleus on the sleep/wake cycle)
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Define exogenous zeitgebers
External cues that may affect or ENTRAIN our biological rhythms (such as the influence of light on the sleep/wake cycle
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What is the suprachiasmatic nucleus?
The SCN is a tiny bundle of nerve cells located in the hypothalamus that is an endogenous pacemaker that maintains the circadian sleep/wake cycle.
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What does the suprachiasmatic nucleus do?
It receives information about light directly from the optic chiasm (an area where nerve fibers connected to the eye cross on their way to the visual area of the cerebral cortex).
This continues even when our eyes are closed, enabling the biological clock to adjust to changing patterns of light.
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Who conducted a study on the endogenous zeitgeber the SCN in animals?
Decoursey in her chipmunk study.
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Outline Decoursey's study on the SCNs influence
- Procedure: Decoursey destroyed the SCN connections in the brains of 30 chipmunks and then returned them back to their natural habitat to be observed for 80 days.
- Findings: The sleep/wake cycle in the chipmunks disappeared and by the end of the study a significant proportion had been killed by predators due to warped sleeping patterns. This highlights the importance of the SCN as a endogenous pacemaker for the sleep/wake circadian rhythm.
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Who conducted the 'mutant hamster' study?
Ralph et al.
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Outline the 'mutant hamster' study and findings
- Procedure: Ralph bred 'mutant hamsters' with a 20-hour sleep/wake cycle. SCN cells from the fetal tissue were transplanted into the brains of normal hamsters.
- Findings: the normal hamsters who had the transplant experienced a default of the sleep/wake cycle to 20 hours, this highlights the role of the suprachiasmatic nucleus in establishing and maintaining the circadian sleep/wake cycle.
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How is the SCN connected to melatonin production?
The SCN passes information on day length and light received to the pineal gland. During the night, the pineal gland secretes melatonin - a chemical that induces sleep and is inhibited during periods of wakefulness.
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Evaluate endogenous pacemakers + the sleep/wake cycle.
- Rhythms independent of the SCN
One limitation of SCN research is that it may be overestimated in the sleep/wake cycle. Research has revealed numerous circadian rhythms in organs and cells of the body labelled PERIPHERAL OSCILLATORS. These peripheral clocks can be influenced by the SCN, however, can act independently. A study demonstrated that changing feeding patterns in mice could alter the circadian rhythm in hepatic cells for up to 12 hours whilst leaving the SCN rhythm unaffected. This implies that there are many other complex influences on the sleep/wake cycle excluding the SCN.
- Interactionist.
There are limitations in terms of research. Endogenous pacemakers cannot be studied in isolation without exogenous interference. Total isolation studies, like Siffre's, are rare and it is suggested that even artificial light can affect the action of endogenous pacemakers such as the SCN. Despite this, in every day life endogenous pacemakers and exogenous zeitgebers interact either way so separating them for research purposes doesn't make sense. For this reason, studies isolating endogenous pacemakers may be limited in validity.
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How do exogenous zeitgebers reset our biological clocks
Through a process known as entrainment - in the absence of external cues the 'free-running' biological clock continues in a cyclical pattern but is then 'brought into line' (entrained) by environmental cues.
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What is the endogenous pacemaker in the sleep/wake cycle?
The suprachiasmatic nucleus
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What are the exogenous zeitgebers in the sleep/wake cycle?
- Light
- Social cues
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Who studied the effect of the exogenous zeitgeber light on the sleep/wake cycle?
Campbell and Murphy
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Outline the study of light on the sleep/wake cycle?
Campbell and Murphy demonstrated how light can be detected by skin receptor sites on the body even when the same information is not received by the eyes - arguing the influence of exogenous zeitgebers on the sleep/wake cycle.
- Procedure: 15 participants were woken at various times and a light pad was shone on the back of their knees.
- Findings: The researchers managed to produce a deviation in the participants sleep/wake cycle up to 3 hours. This shows light as a powerful exogenous zeitgeber that need not necessarily rely on the eyes to exert influence on the brain.
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How are social cues an exogenous zeitgeber on the sleep/wake cycle?
Babies, in the early days, do not abide by a sleep/wake cycle - with their sleeping and waking being random.
At around 6 weeks circadian rhythms begin and at 16 weeks, babies rhythms are entrained by schedules imposed such as adult-determined meal times and bed times.
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Evaluate exogenous zeitgebers + the sleep/wake cycle
- Environmental disparity.
Exogenous zeitgebers do not have the same effect in all environments. For people who live in places with little darkness in summer and prolonged darkness in winter, their sleep/wake cycle remains normal all year round despite witnessing unnatural light change. This suggests that the sleep/wake cycle must be predominantly controlled by endogenous pacemakers that can override any environmental light change.
- Case study evidence
There is limitations for the exogenous zeitgeber of social cues provided by a case study. A young man, blind from birth had a circadian rhythm of 24.9 hours. Despite exposure to social cues, he could not adjust his sleep/wake cycle and subsequently had to take sedatives at night and stimulants in the morning. This suggests that social cues alone are not effective in resetting / entraining the circadian rhythm.
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What is included in the topic: 'The nervous system and the endocrine system' ?
- What the nervous system is and it's two main functions
- The two subsystems: CNS and PNS
- The CNS: brain (2 hemispheres) and the spinal cord and responsibilities.
- The PNS: The ANS and SNS + functions.
- The endocrine systems glands and hormones
- The fight or flight response
- Role of adrenaline, it being immediate and automatic and parasympathetic action.
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What is included in the topic: 'Neurons and synaptic transmission' ?
- The 3 types of neurons: sensory, relay and motor.
- Differences between each neuron
- Structure of neuron: soma, nucleus, dendrites, axon, myelin sheath, nodes of Ranvier, terminal buttons and synapse.
- Synaptic transmission (electrical to chemical) and neurotransmitters
- Excitation and inhibition and summation.
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What is included in the topic: 'Localization of function in the brain' ?
- Localization (Broca and Wernicke) vs holistic theory.
- The idea of lateralization (hemispheres controlling opposite sides)
- The 4 lobes: Frontal, Parietal, Occipital and Temporal
- Different areas: Motor area (frontal), somatosensory area (parietal lobe), visual area (occipital lobe) and the auditory area (temporal lobe) *and what damage does*.
- The two language centers of the brain: Broca's area (left frontal lobe associated with speech production) and Wernicke's area (left temporal lobe associated with speech comprehension).
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What is included in the topic: 'Hemispheric lateralization' ? (goes w/ split brain research but too long)
- Localization and lateralization (such as visual areas appearing in both)
- Left and right hemispheres --> language is lateralized (LH analyzer, RH synthesizer), and non-lateralized functions (vision, somatosensory and motor areas being in both hemispheres).
- How the motor area works (contralateral wiring) - opposite hemispheres control different sides of body
- How vision works (contralateral and ipsilateral) --> and similar for auditory.
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What is included in the topic: 'Split-brain research' ?
- What severing the corpus callosum does (epilepsy)
- Sperry's research.
- Procedure: Object flashed to LVF (linked to RH) and flashed to RVF (linked to LH), *verbal description*
- Procedure: *Touch recognition:* Selecting a matching object out of sight linked to picture
- Procedure: *Drawing task* asked to draw object flashed to LVF and RVF
- Conclusions about lateralization of functions.
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What is included in the topic: 'Plasticity and functional recovery after trauma' ?
- What is meant by plasticity and synaptic pruning
- Research into plasticity: Maguire taxi-cabs 'The Knowledge' with structural difference grey matter in the posterior hippocampus, and Draganski's medical students seeing learning induced changes occurred in the PH and parietal cortex 3 months before and after final exams
- Functional recovery following brain trauma (example of neuroplasticity) occurring quickly in *spontaneous recovery* up to several weeks or months
- What happens in functional recovery: axonal sprouting, denervation supersensitivity and recruitment of homologous areas.
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What is included in the topic: 'Ways of studying the brain' ?
- fMRI's and how they work: hemodynamic response producing 3d images (activation maps)
- Electroencephalogram and how they work to detect arrhythmic patterns
- Event-related potentials and how they work --> using a statistical averaging technique that filters EEG recordings, making ERPs.
- Post-mortem examinations: analysis of brain following death, looking at areas of damage being afflicted with cognitive processes or behaviour.
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What is included in the topic: 'Biological rhythms: circadian rhythms' ?
- What biological rhythms are
- What a circadian rhythm is
- The sleep/wake cycle as an example of a circadian rhythm, including effects of light (exogenous) and the SCN (endogenous)
- Siffre's cave study
- Aschoff and Wever bunker study, and it's similarities to Siffre in conclusions (sleep/wake cycle longer than 24 hours but entrained)
- Opposing research: Folkard's cave study changing the speed of the clock suggesting that strong-free running circadian rhythm cannot be easily over ridden by exogen zeit.
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What is included in the topic: 'Biological rhythms: infradian and ultradian rhythms' ?
- What an infradian rhythm is
- The menstrual cycle as an example of infradian rhythm
- Stern and McClintock's period study on exogenous factors, such as pheromones, on infradian menstrual cycle.
- Seasonal affective disorder as an example of an infradian rhythm and it's mechanism w/ the sleep/wake cycle --> pineal gland releasing melatonin that affects serotonin production. (can be defined as *circannual* and also *circadian* due to mechanism.
- What ultradian rhythms are
- The *stages of sleep*, 1 and 2 *alpha waves*, 3-4 SWS *delta waves*, 5 (REM) *theta waves*.
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What is included in the topic: 'Endogenous pacemakers and exogenous zeitgebers' ?
- What an endogenous pacemaker and exogenous zeitgeber is
- Role of SCN in circadian rhythms (sleep/wake cycle)
- Animal studies with the SCN: **Decoursey** chipmunk study and **Ralph** mutant hamster study.
- Exogenous zeitgebers and the sleep/wake cycle
- Role of light study: **Campbell and Murphy**
- Role of social cues in sleep/wake - babies entrained and research on jet lag.
