Paper 2: Topic 6: Biopsychology Flashcards
What are the 5 divisions of the nervous system
- The Central Nervous System
• Brain (centre of conscious awareness) & Spinal Cord (reflex actions)
• Coordinates incoming sensory information and sends instructions to other parts of the NS
• Cerebral cortex comprises grey and white matter - The Peripheral Nervous System
• Network of nerve fibres (axons) that connects parts of the body with the CNS
• Transmits messages from the CNS to muscles/glands - The Somatic System
• Conscious movement; myelination enables rapid transmission; reflex arc - The Autonomic Nervous System
• Involuntary bodily functions (eg breathing, heartbeat)
• Transmits information between organs; not as fast (unmyelinated) - Sympathetic & Parasympathetic Nervous System
• Fight or flight (sympathetic) and rest & digest (parasympathetic)
What’s the nervous system
The body’s main communication system which is very fast acting.
• It is a complex network of specialised nerve cells (neurons) which pass information around the body using electrical signals and chemicals (neurotransmitters).
What are the 2 divisions of the human nervous system
The central nervous system
The peripheral nervous system
What’s the 2 subdivisions of the peripheral nervous system
The autonomic nervous system
The somatic system
What’s the 2 subdivisions of the autonomic nervous system
Sympathies division
Parasympathetic division
What’s the central nervous system
Brain - centre of conscious awareness
Spinal cord - reflex actions
Function of the central nervous system
-Coordinates incoming sensory information and sends instructions to other parts of the NS.
-This is our store of knowledge and habits.
Structure of the central nervous system
Made up of the brain and spinal cord
• The brain is the centre of conscious awareness
• The cerebral cortex (3mm outer layer) is highly developed in humans and distinguishes our higher mental functions from other animals
• The spinal cord is an extension of the brain. It is responsible for reflex actions
Describe the cerebral cortex of the central nervous system
Outer layer of the brain
Cerebral cortex is also known as grey matter due to the colour of it.
Grey matter is made up of cell bodies.
The white matter is made up of axons which form fibre tracts
Structure of the peripheral nervous system
-made up of a Network of nerve fibres (axons) which are connected to the CNS
-it sends info to the CNS from the outside world and transmits messages from the CNS to muscles and glands (effectors) in the body
Describe the somatic nervous system of the peripheral nervous system
-controls conscious movement as it sends instructions from CNS to effectors in muscles and glands
-transmits info from receptor cells in sense organs to the CNS (takes info from external environ.)
-needs to act quickly as it’s made up of myelinated neurons
Describe the reflex arc of the somatic nervous system
1) stimulus detection: sensory receptor detects a stimulus
2) sensory neuron activation: The sensory receptor sends an electrical impulse along a sensory neuron towards the central nervous system (CNS), typically the spinal cord.
3) relay neuron: In the spinal cord, the action potential reaches an integration centre (usually a synapse) between the sensory neuron and a motor neuron or an interneuron, which then relays the signal.
4) motor neuron activation: The impulse is transmitted to a motor neuron. The motor neuron carries the signal away from the CNS to an effector.
5) effector response: The effector, which is usually a muscle or gland, produces a response. For instance, in the hot object scenario, the effector would be the muscles in your arm, causing you to withdraw your hand quickly
Describe the pathway of the somatic nervous system
Stimulus -> sensory neuron -> relay neuron -> motor neuron -> effector (muscle/gland)
Function of the autonomic nervous system
-controls involuntary boldly functions which aren’t consciously directed eg: breathing, heartbeat, digestive processes and sexual arousal
-only transmits info to and from internal bodily organs (don’t need sensory pathways)
-acts more slowly than the SNS (somatic) and therefore made of unmyleinated nerve fibres
- divided into sympathetic and parasympathetic nervous system
Describe the sympathetic divisions of the autonomic nervous system
works with the endocrine system to get the body prepared for fight or flight
Describe the parasympathetic divisions of the autonomic nervous system
works with the endocrine system to return the body to its normal resting state (rest and digest).
Brief:
What does the PNS system consist of and function
Network of nerve fibres
Connects parts of the body with CNS
Brief:
What does the ANS system consist of and function
Network of unmyelinated nerve fibres (slower acting)
Controls the automatic functions of the body e.g. breathing, heart rate Connects the senses and the organs with the CNS
Concerned with emotions, threats and bodily changes
Brief:
What does the SNS system consist of and function
Network of myelinated sensory and motor neurons (quicker acting)
Controls the conscious movement e.g. reflex of touching a hot pan
Carries sensory information from the outside world and internal organs to the CNS (sensory neurons)
Carries instructions for movement from the CNS (motor neurons)
What’s the function of the spinal cord
Responsible for reflex actions
Ensures signals from the brain are transmitted to the rest of the body through the Peritheral nervous system
2: Structure and functions of neurons
What is a neuron?
Specialised nerve cells which are part of the nervous system
80% of neurons are located in the brain and 20% are in the spinal cord, peripheral nervous system, and the gut (gut brain axis)
2: Structure and functions of neurons
How do neurons transmit info?
electrically (through action potentials)
chemically (using neurotransmitters)
2: Structure and functions of neurons
What do all neurons consist of?
-Cell body
-dendrites
-mylien sheath
-axon
-nodes of ranvier
Dendrites receive signals; action potentials propagate the signal down the axon to the axon terminal, stimulating the release of neurotransmitters
2: Structure and functions of neurons
What are dendrites and what do they do?
Dendirtes protrude (stick out) from the cell body, these carry nerve impulses (action potentials) from neighbouring neurons towards the cell body
2: Structure and functions of neurons
What is the function of the cell body?
Includes a nucleus which contains the genetic material of the cell
Also called the Soma
2: Structure and functions of neurons
What is the axon?
Carries action potential away from the cell body down the length of the neuron. It’s covered in a myelin sheath that protects the axon and speeds up electrical transmission of the action potential
2: Structure and functions of neurons
What is the axon terminal and myelin sheith
Protrude from the axon and form synapses with the dendrites of the neighbouring neuron
Covers the axon, protects the axon and speeds up electrical transmission of the impulse
It’s segmented by gaps called nodes of ranvier which speed up the transmission by forcing it to ‘jump’ across the gaps along the axon
2: Structure and functions of neurons
What disease results from degeneration of the myelin sheath?
Multiple Sclerosis.
A chromic autoimmune disorder where the immune system attacks the myelin sheath in the CNS, causing slowing of neurotransmissiom, resulting in symptoms like fatigue, numbness, weakness, vision problems, difficulty with coordination and balance and cognitive issues
2: Structure and functions of neurons
Describe the neuron pathway
Stimulus -> sensory neurons -> relay neurons (in brain) -> motor neuron -> response
Sensory input -> integration -> motor output
2: Structure and functions of neurons
What size dendrites and axons do sensory neurons have?
Sensory neuron – afferent (incoming to the brain) neurons
Long dendirtes and short axons.
Cell Body is in the middle of the spinal cord.
2: Structure and functions of neurons
Function of sensory neuron
Take sensory information from the environment and sends signals to the brain and convert a specific type of stimulus by their receptors into action potentials
2: Structure and functions of neurons
Do all messages go to the brain from sensory neurons
No. Some end in the spinal cord to allow reflex actions to occur quickly without the delay of sending impulses to the brain
2: Structure and functions of neurons
What size dendrites and axons do motor neurons have?
Efferent (outgoing) neurons
Short dendrites: connect to axons of relay neurons
Long axons: to connect to effector organs
2: Structure and functions of neurons
Function of motor neurons
Take messages from the CNS to effectors like glands and muscles
2: Structure and functions of neurons
Where is its cell body and axon located in motor neurons?
in the spinal cord
Fibre (axon) projects outside the spinal cord to directly or indirectly control effector organs
2: Structure and functions of neurons
What size dendrites and axons do relay neurons have?
Interneuron Neurons
Short dendrites and short axons – as they don’t have to span long distances and aren’t myelinated
2: Structure and functions of neurons
What is the function of relay neurons
Connect sensory neurons to the motor or other relay neurons
Allow motor neurons and sensory neurons to communicate with eachother
Found only in the brain and spinal cord. Make up 97% of all neurons
2: Structure and functions of neurons
Give an example of when relay neurons are used in the reflex arc
Patellar reflex
Reflex arc:
1) Stimulus detection: sensory receptor detects a stimulus
2) Sensory neuron activation:
3) Relay neuron:
4) Motor neuron activation:
5) Effector response:
2: Structure and functions of neurons
Describe the human connectors project
Sensory receptors synapses with inter neuron in spinal cord. Inter neuron synapse with motor neuron which causes contract in quadriceps so leg move
2: Structure and functions of neurons
Define the nodes of ranvier
Gaps between the myelin sheath which speed up transmission by making by action potential ‘jump’ across the gaps along the axon
3: synaptic transmission
What is the process of synaptic transmission?
one neuron communicates with another by releasing neurotransmitters to diffuse across the synapse
Electrochemical transmission of nerve impulses through infra-neuronal propagation of action potentials and inter-neurornal release of neurotransmitters that bind to post-synaptic receptors, affecting the electric charge of the post-synaptic neuron and prosperity to fire and an action potential
3: synaptic transmission
Explain what the synapse is.
The gap between the presynaptic neurons axon terminal and the post synpaic neurons dendrites/cell body where neuronal communication continues via release/uptake of neurotransmitters that diffuses across the gap
3: synaptic transmission
How does a neurotransmitter work?
How neurons communicate chemically
1) The electrical signal arrives at the axon terminal of the presynaptic neuron, the neurotransmitter to be released over supposed
2) Neurotransmitters bind to completely Receptors on the post synaptic neuron
3) This activation of the receptor determines whether the post-synaptic neuron will generate an alectrical signal
3: synaptic transmission
Explain how an action potential works
(Electrical impulse)
When a neuron is in a resting state, it’s negatively charged compared to the outside
When a neuron is activated by a stimulus, if this causes to become more positively charged it caused an action potential to travel down the axon
3: synaptic transmission
How does an action potential cause release of a neurotransmitter?
1) Action potential travels along the axon to the axon terminal of the presynaptic neuron
2) This triggers the vesicles to migrate towards and bind to the presynaptic memebrane and release neurostamnsitters
3) Neurotransmitters diffuse across the synapse and bind with the post synpaic receptors like a lock and key
3: synaptic transmission
Name 4 neurotransmitters
Adrenaline – right or flight
GABA – claiming, reduces anxiety (links to benzodiazepines for treating OCD) – inhibitory
Noradrenaline – concentration
Dopamine – pleasure
3: synaptic transmission
Explain how excitation works, and what is an EPSP?
Excitatory effects facilitate the firing of action potentials, promoting alertness and activity, if a neurotransmitter is excitatory , it leads to the generation of a excitatory postsynaptic potential (EPSP) leading to a positive charge at the postsynaptic membrane.
Makes the inside of the postsynaptic neuron less negitive compared to outside, moving the membrane potential closer to the threshold needed to trigger an action potmetial.
It’s more likely that the neuron will fire an action potential.
3: synaptic transmission
Explain how inhibition works, and what is an IPSP?
help to calm the mind and body and involved in inducing sleep.
When a neurotransmitter caused an inhibitory effect, it leads to the generation of an inhibitory postsynaptic potential (IPSP) leading to a negitive charge at the postsynaptic membrane.
Makes the inside of the postsynaptic neuron more negitive compared to the outside, moving the membrane potential further away form the threshold needed to trigger an action potential.
Making it less likely that the neuron will fire an action potential .
3: synaptic transmission
Explain temporal summation and spatial summation
Temporal: the combined effects of inputs over time
Spatial: the combined effects of inputs across multiple neurons
Summation:
A nerve cell can receive both EPSP and IPSPs at the same time
Summation is the net sum of the total IPSPs and EPSPs which determines whether or not the cell fires. The threshold is -60v for an action potential to be created.
4: endocrine system
What is the endocrine system?
A communication system that instructs glands to release hormones directly into the bloodstream which carry the hormones to the target organs (effectors). It works along side the NS to control vital bodily functions.
4: endocrine system
What speed does the endocrine system pass messages compared to the nervous system?
It acts slower than the NS but still has powerful effects
4: endocrine system
What is a hormone?
A chemical substance that circulates the bloodstream and affects target organs. Produced in large quantities.
They have a slower release but longer action than neurotransmitters
4: endocrine system
Label the diagram on the Cornell notes of the glands
.
4: endocrine system
What does the hypothalamus do?
Brain region connected to the pituitary gland.
Responsible for stimulating or controlling the release of hormones from the pituitary gland.
It’s the control system which regulates the endocrine system
4: endocrine system
What are the 2 adrenal gland regions?
-adrenal cortex (outside)
-adrenal medulla (inside)
4: endocrine system
What is released from the adrenal medulla gland and what impact does it have:
Secretes adrenaline and noradrenaline for the fight or flight response
4: endocrine system
What is released from the testes glands and what impact does it have:
Secretes testosterone which is responsible for the male sex charectaristics during puberty and muscle growth
4: endocrine system
What is released from the adrenal cortex glands and what impact does it have:
Secretes cortisol which stimulates the release of glucose to provide the body with energy whilst suppressing the immune system
4: endocrine system
What is released from the ovaries glands and what impact does it have:
Secretes oestrogen which regulates female reproductive system including menstral cycle and pregnancy
4: endocrine system
What is released from the pineal glands and what impact does it have:
Secretes melatonin which regulates sleep-wake cycle
4: endocrine system
What is released from the pituitary gland and what impact does it have:
Secretes Growth hormone, prolactin, ACTH, TSH, FSH, ADH, oxytocin
(The majority of hormones abreviated into capital letters are secreted by the pituary gland)
It’s the master gland that regulates other endocrine glands, controls growth, lactation, stress response (ACTH) and water balance (ADH)
5: fight or flight response
What is a gland?
Specialised organ that produces and secretes hormones, enzymes and fluids into the bloodstream
5: fight or flight response
What is a hormone?
A chemical messenger produced by glands that regulates various physiological processes in the body by affecting target cells or organs
5: fight or flight response
Name 8 major endocrine glands
Hypothalamus – part of CNS – connects to pituatory gland (the master gland)
Thyroid – metabolism
Testes – testostrione
Ovaries – oestorgen and progesterone
Adrenal glands – fight and flight
Pancreas – controls blood sugar
5: fight or flight response
Which two biological systems combine to implement the fight or flight response?
Endocrine system and nervous system, necessary to sustain arousal
5: fight or flight response
What phrase is used when talking about fight or flight?
‘Make the body prepared’
A sequence of activities within the body that are triggered when the body prepares itself for defending or attacking (fight) or running away to safety (flight)
5: fight or flight response
What’s the evolutionary origin of the fight or flight response
It’s our engrained survival instinct And represents the options our ancient ancestors could choose when dealing with dangerous environments
5: fight or flight response
Which brain region is involved in sensing danger, and what is the name of the pathway which is activated by it?
Amygdala
It’s assossiated with emotional processes and is the body’s ‘threat’ sensor
Part of the limbic system
If it alerts that there’s a threat then it will activate a sequence of events (the sympathomedullary (SAM) pathway)
5: fight or flight response
What are the steps of the activation of the SAM pathway?
Amygdala activates the SAM pathway -> Hypothalamus activates -> sympathetic nervous system triggers -> adrenal medulla ->releases/secretes adrenaline and noradrenaline facilitates -> fight or flight response
5: fight or flight response
In detail, what are the steps of the activation of the SAM pathway
1) The amygdala sends distress signals to the hypothalamus which activates the sympathetic branch of the autonomic nervous system (ANS)
- The ANS changes from resting state (parasympathetic) to the physiologically aroused (sympathetic)
2) This triggers the adrenal medulla to relase the stress hormone adrenaline into the blood stream
- Adrenaline triggers physiological changes in the body eg: increases heart rate which prepares the body for the fight or flight response
3) One the threat has passed the parasympathetic NS return sbody to its resting state and bodily functions (rest and digest). The parasympathetic NS and sympathetic NS work as an antagonistic pair; when one is activates the other isn’t. Eg: Heart rate and blood pressure return to resting level and pupils constrict, bladder control is regained and liver stored glucose in the form of glycogen for future use
5: fight or flight response
List 5 effects of the role of adrenaline
increase your heart rate: pushing blood to the muscles to enable action and to the brain to facilitate rapid response planning to prepare the body for action
-pupillary dilation: allows more light into eyes and to increase awareness of visual information to prepare the body for action
-breathing becomes more rapid to take in more oxygen to provide to the muscles to aid movement to prepare the body for action
-blood sugar (glucose) and fats are released into the bloodstream to provide energy to provide the body for action
-diversion of blood away from the digestive system to conserve energy by constricting blood vessels to provide the body for action
-increase in sweating: to cool your body
5: fight or flight response
Describe the involvement of the HPA Axis in the stress response
1) Detection of stress: when encountering a stressor (physical, emotional or psychological) the hypothalamus senses this and activated the HPA axis
2) Release of CRH: hypothalamus scope creates cortiotropin-releasing hormone (CRH) Into the blood, which travels to the pituitary gland
3) Release of ACTH: in response to CRH, the pituatory gland releases adrenocortiotropic hormone (ACTH) into the blood stream
4) Stimulation of the Adrenal glands: ACTH reaches the adrenal glands and stimulates the adrenal cortex to produce and release the hormone cortisol
5) Effects of cortisol: cortisol helps mobilise energy by increasing glucose in the bloodstream, enhancing brains use of glucose and increasing availability of substances that repairs tissue. It curbs functions thay would be nonessential in the fight ornfligh situation eg: growth, reproduction, digestion
6) Short term and long term effects: ST – enables te body to repsond to threats, but chronic activation can lead to impaired cognition and immunity and has been linked to anxiety, depression and weight gain
5: fight or flight response
Compare the HPA axis and the SAM pathway
HPA axis is activated more slowly (minutes to hours) and releasing cortisol
SAM pathway provides a more rapid and immediate response, releasing adrenaline
HPA Axis: cortisol hormone
SAM pathway: adrenaline hormone
8/16 marker hasn’t come up before:
5: fight or flight response
3 limitations of the Fight or flight response
P: negitive consequences on the body in todays modern world
Eg: stressors of modern life don’t generally need such a physical reaction that gives us energy to fight or flight as they’re more psychological and longer term
Ex: the problem for modern humans arises when the stress response is repeatedly activated. This increases levels of cortisol which in small amounts is good but too much of it suppresses the immune system
L: it’s not always helpful in todays modern world. By learning coping strategies like breathing techniques people can learn how to activate the parasympathetic NS and reduce these negitive consequences
P: gender differences in the acute stress response which are ignores and presents a beta bias
Eg: Taylor suggests females may display a different patterns to males. She argues that females protect themselves and their young through nurturing behaviours (tending) and forming protective alliances with other women (befriending)
Ex: women may have a completely different system to coping with stress because their responses evolved in the context of being the primary caregiver of their children. Fleeing too readily would put their offspring at risk
L: so the theory many minimise the differnce between male and females
P: incomplete explaination
Eg: Gray argues that the first phase of reaction to a threat is not to fight or flee but to avoid confrontation. He suggests that prior to responding with attacking or running away, most animals typically display the ‘freeze’ response to ‘stop, look and listen’ response.
Ex: adaptive advantages of this for humans is that ‘freezing’ focuses attention and makes them look for new info in order to make the best response to the threat.
L: this suggests that the original theory is only a partial explaination to how danger reacts to immediate short term danger
6: localisation of function
What does localization of function mean?
The concept of functions including movement, speech and memory are performed in/ specific to distinct regions of the brain (localised)
This includes the motor cortex, somatosensory cortex, auditory cortex and visual cortex
For example, Broca’s area is specific to language production.
6: localisation of function
How does localisation of function contrast to a holistic view?
It suggests all parts of the brain are involved in the processing of thought and action
Before scientific study of the brain, it was generally believed that the brain worked holistically i.e. all parts together for all functions
Nowadays the brain is seen as more locialised for specific functions
6: localisation of function
What is the outer layer of the brain / both hemispheres called?
Cerebral cortex (grey matter)
3mm thick
Grey – Cell bodies and dendirtes
6: localisation of function
What are gyri and sulci?
On cerebral cortex:
Gyri – outer folds
Saulci – inner folds
Increases surface area to volume ratio
6: localisation of function
What is the hemispheric lateralisation of function?
concept that different hemispheres in the brain have differing functions. For example, the language functions are typically lateralised to the left hemisphere of the brain.
Lateralisation: some of our physical and psychological functions are controlled or dominated by a particular hemisphere.
Left and right hemispheres are separated
Contralateral control: right hemispheres activity including motor cortex controls left side, left hemispheres activity including motor cortex controls right
6: localisation of function
What are the 4 lobes of the brain called?
Frontal lobe – persona, wernickes area
Parietal lobe – sensory perception and awareness
Occipital lobe – vision
Temporal lobe – auditory, speech, Broca’s area
Cerebellum – movement, breathing, unconscious actions
Frontal lobe and parietal lobe is seperated by central salcus
Central salcus- separates motor cortex and somatosensory cortex
Everything on motor cortex side is frontal lobe side
Somatosensory cortex is on parental love side
6: localisation of function
What is the role of the limbic system?
Midbrain, unique to only mammals
Includes: Thalamus, Striatum, Amygdala
MacLean – suggests it’s centre of emotion and learning
6: localisation of function
Who were 2 neurosurgeons known for identifying areas of the brain associated with speech processing?
Broca:
Identified a small area in the left posterior frontal lobe for speech production. Lesions in this area causes Brocas aphasia which is chaarectarised by speech that’s slow, laborious and lacking in fluency
Inferior frontal gyrus
Wernicke:
Studied patients with severe difficulties in understanding language but no problems speaking and producing it.
He identified an area in the left posterior temporal lobe as being responsible for speech comprehension – Wernickes area
Patients with Wernickes aphasia often produce nonsense words eg: word salad
6: localisation of function
What is Broca’s aphasia, and how is it caused?
Studied patient named Tan and eight other post mortems who had speech production issues and lesions in their left frontal hemisphere
Led Broca to identify the existence of a language centre for speech production in the posterior portion of the frontal lobe of the left hemisphere (Brocas area)
Those with it stuggle with speech production
6: localisation of function
What is Wenicke’s aphasia, and how is it caused?
Studied a patient who suffered a stroke and could not understand language. He studied his brain post-mortem
Led Wernickesto identify that the area of the brain involved in understanding language was in the posterior portion of the left temporal lobe (Wernickes area)
Those with it stuggle with speech comprehension
6: localisation of function
How is the case of Phineas Gage seen as evidence for the localisation of function?
1848 Railroad
25 years old
Iron pole went through his gages left check through his left eye and exciting his skull and loosing most of his left frontal lobe
Survived but severe personality changes from calm to quick-tempered and rude
Change in temperament suggests the frontal lobe may be responsible for regulating mood
Case study - can’t extrapolate
6: localisation of function
What is the role of the frontal lobe
Where the motor area is located, it’s responsible for voluntary movements by sending signals to muscle in the body and personality eg: Phineas Gage
6: localisation of function
What’s the role of the parietal lobe
Receives sensory information from the skin to produce sensations related to pressure pain, temperature, etc. different parts of the somatosensory area receives messages from different locations of the body
6: localisation of function
What’s the role of the occipital lobe
At the back of the brain, where the visual area is located. contains different parts that process different types of information including colour, shape or movement.
6: localisation of function
What’s the role of the temporal lobe
Where the auditory area is located (Superior temporal gyrus – upper temporal outer lobe). Responsible for analysing and processing acoustic info. The auditory area contains different parts, and the primary auditory area is involved processing simple features of sound including loudness, tempo and pitch.
6: localisation of function
What’s the role of the left frontal lobe
Where Broca’s area is found in the left frontal lobe and is thought to be involved in fluent language production
6: localisation of function
What’s the role of the left temporal love
Where Wernickes area is found In the left temporal lobe and is thought to be involved in language comprehension
6: localisation of function
How is the spatial arrangement of the motor cortex linked to its function?
Role of the motor area is to control volentrary motor movement by sending signals to muscles in the body
It also controls muscles on the opposite side of the body, eg: left hemisphere controls muscle movement on the right, vise versa.
Regions of the motor area are arranged in a logical order, eg: region controlling finger movement is located next to the region that controls the hand
6: localisation of function
Strengths of localisation of function
P: lots of evidence from brain scans which provides support that neurological functions are localised
Eg: Tulving revealed that semantic and episodic memories red side in different parts of the prefrontal cortex with semantic memories in the left hemisphere and episodic in the right.
Peterson revealed how Wernickes area was active during a listening task and Broca’s area during a reading task.
Ex: these studies show the different areas of the brain are active during different cognitive functions, demonstrating a localisation of function. Modern imaging methods also identified the functional connectivity of spatially distributed brain circuits, rather than individual brain regions, to be involved in the
Performance of cognitive function Suggesting that functional localisation Invoves brain circuits not just isolated regions
L: Increases validity as it supports idea that different brain regions carry out different functions.
P: evidence from case studies from patients with brain damage that helped develop our understanding
Eg: patient HM who had experimental surgery which removed his hippocampus following epileptic seizures after an accident. After the hippocampus was removed, he was no longer able to transfer episodic episodic and semantic memories from his STM to his LTM but was able to learn new procedural tasks eg: mirror drawing task
Ex: this shows that the hippocampus has a role in formation of new LTM memories, expect procedural memories which are assossiated with the motor cortex and the cerebellum and basil ganglia
L: case studies like HM and Broca’s ‘patient Tan’ who could only produce a single syllable after lesions in his Broca’s area, provides researchers with an in-depth understanding of the role of certain regions in the brain and increases the validity of the theory
6: localisation of function
Limitation of localisation of functions
P: critised by researchers arguing the brain works holistically.
Eg: Lashley’s principle of equipotentiality suggests basic motor and sensory functions are localised, but higher mental functions are not. His study on rats (removing 10–50% of the cortex) found no area more crucial than others. He claimed cortical areas could compensate for lost cognitive functions after injury.
Ex: He argued localisation is biologically reductionist, oversimplifying complex behaviours and cognition.
L: A holistic approach is needed to understand complex processes like language. Modern imaging highlights functional connectivity and distributed circuits (e.g., limbic or fronto-striatal systems) rather than isolated regions.
P: fails to consider individual differences
Eg: Harasty et al. found larger Broca’s and Wernicke’s areas in females, possibly explaining their greater ease with language. This introduces beta bias, as the theory overlooks gender differences and variations in brain size and activity, leading to inaccurate generalisations.
Ex: Individual differences also include age-related changes in brain function and plasticity, which are crucial for developing effective neurological treatments. Ignoring them can reduce intervention effectiveness.
L: Generalising localisation research without considering gender differences is problematic. Future studies should use diverse samples to tailor theories to individual characteristics, improving their applicability.
7: hemispheric lateralisation
What does hemispheric laterlisation mean?
Concept that the 2 different hemispheres (halves) in the brain have differing functions. Eg: the language functions are typically lateralised to the left hemisphere of the brain. Certain mental process and behaviours are mainly controlled by one hemisphere rather than another
The divisions of functions between two hemispheres .
7: hemispheric lateralisation
What is the difference between localisation and lateralisation?
Hemispheric lateralisation is specific to functions in the 2 hemispheres whereas localisation of function is about specific regions of the brain controlling specific functions
7: hemispheric lateralisation
Which hemisphere processes the left visual field
The right hemisphere
The brain is comtralateral- left side controls right visa versa
7: hemispheric lateralisation
Which hemisphere processes the right visual field?
Left
7: hemispheric lateralisation
Where does the left visual field project to on the retina?
Left eye: nasal retina
Right eye: temporal retima
Right side of the brain process info from left side of bod (eg: visual info from the left visual field) yet both eyes process it
7: hemispheric lateralisation
Which part of the retina sends information to the contralateral hemisphere?
Where does this occur?
Info from Nasal retima crosses to comtralateral hemisphere at the optic chiasm
7: hemispheric lateralisation
Which part of the retina does not send information to the contralateral hemisphere, and where is it sent?
Temporal retina so remains in the ipsilateral hemisphere
7: hemispheric lateralisation
Where does the right visual field project information to?
Right eye: nasal retina
Left eye: temporal retina
7: hemispheric lateralisation
What happens to visual information if the corpus callosum is severed?
Info arriving at the cortex can’t be exchanged between hemispheres
Each hemisphere will only be aware of the contralateral info
7: hemispheric lateralisation
Which hemisphere is language largely processed in?
Left
Where Broca’s area and Wernickes area are located
Broca – speech production
Wernicke – speech processing and comprehension
7: hemispheric lateralisation
Which hemisphere are faces and facial emotion processed in?
Right
Right doesn’t have verbal language
7: hemispheric lateralisation
Who conducted experiments on split-brain patients?
Sperry
7: hemispheric lateralisation
Define split brain research
serious of studies on people who have 2 separated hemispheres of their brain.
This occurred because of serious epilepsy, epileptic patients who had experienced a surgical separation of the hemispheres at the corpus callosum (a commissurotomy)
This allowed researchers to investigate the extent to which brain function is lateralised as the electrical discharge of epilepsy can’t move across to the whole brain
7: hemispheric lateralisation
What was Sperry’s experiment?
He realised that split brain patents who had a commissurotomy could be studied hemispheric lateralisation
Procedure: the divide field method. Ppts look ahead at the dot in the centre of the screen and see one item to the left (of their visual field) and one item to the right (of their visual field) for 0.2 secs
7: hemispheric lateralisation
Why was the visual stimulus presented so briefly?
So it only appears in one hemisphere To prevent subjects from moving their eyes, and thus transferring information between the visual fields
7: hemispheric lateralisation
What happened when visual information was presented to the right visual field and why?
Processed by the left hemisphere
The left hemisphere is dominant for verbal processing, the patients answer matches the word
7: hemispheric lateralisation
What would happen when visual information was presented to the left visual field, and why?
The right hemisphere can’t share info with the left, so late it is unable to say what he saw, but can draw it
7: hemispheric lateralisation
What happened when participants were asked to recognise objects presented to the left visual field by touch
Object in right hand:
Processed by left hemisphere
Could describe wha they felt, could identify the object by selecting similar object from a series of objects
Object in left hand:
Processed by right hemisphere
Couldn’t describe what they felt, so made guesses
But left hand could identify a test object, by selecting a similar object from a series of a objects
7: hemispheric lateralisation
What happened when composite faces (composed of a female and a male face), and why?
Picture presented to right visual field:
Processed by left hemisphere
While right hand would attempt to draw a picture, it wasn’t as clear as left hand picture as right hemisphere is dominant for visual motor tasks
Picture presented to left visual field:
Left hand (controlled by right hemisphere) would consistently draw clearer and better pictures than the right hand (even though all ppts were right-handed)
7: hemispheric lateralisation
What do we conclude from work on split-brain patients?
The findings of Sperry and Gazzaniga’s research highlights a number of key differences between the two hemispheres.
• Firstly, the left hemisphere is dominant in terms of speech and language.
• Secondly, the right hemisphere is dominant in terms of visual-motor tasks
7: hemispheric lateralisation
Strength and 2 limitations
P: research to support the understanding of hemispheric specialisation
Eg: Luck et al. (1989) showed that split-brain participants are faster than normal controls at identifying the odd one out in an array of similar objects, highlighting specialised hemispheric processing. Kingstone et al. (1995) suggested the left hemisphere’s superior processing is ‘watered down’ by the right hemisphere in typical brains.
L: These findings reinforce Sperry’s conclusions, demonstrating the robustness of hemispheric distinction in function and ability.
Limit:
P: Sperry’s research on split-brain patients is the methodological challenges that may impact the generalizability and internal validity of the findings.
Eg: The study was a quasi-experiment, so participants were not randomly assigned to groups, introducing potential bias. Only individuals with epilepsy severe enough to warrant surgery were included in the experimental group, while the control group consisted of individuals without epilepsy, making epilepsy a potential confounding variable. Furthermore, the small sample size of 11 patients, all of whom had epilepsy, raises concerns about population validity.
Ex: These factors make it difficult to generalize the findings, as the unique characteristics of these patients could limit the applicability of the results to a broader population.
L: Therefore, the study design and the specific characteristics of the participants may reduce the generalizability of Sperry’s conclusions to the general population.
P: A limitation of split-brain research is that newer findings challenge its early conclusions, particularly regarding language lateralization.
Eg: Early research suggested the right hemisphere lacked basic language function, but case studies like J.W. show otherwise. J.W. developed speech using his right hemisphere, allowing verbal expression from either hemisphere.
Ex: This demonstrates the brain’s adaptability, suggesting language may not be strictly left-lateralized. J.W.’s case challenges the oversimplified view of hemispheric lateralization and highlights neural plasticity.
L: Gazzaniga’s findings question the validity of early research, suggesting language functions are more flexible than initially believed, underscoring the need for further study.
- Plasticity and functional recovery
Define plasticity
Brains ability to change and adapt over time as a result of experience and learning
- Plasticity and functional recovery
How the view on brain plasticity has changed
Research has demonstrated that the brain continues to create new neural pathways and alter existing ones in response to changing experiences
Before it was thought that vhs he’s were restricted to the developing brain within childhood and the adult brain has moved beyond a critical period would remain fixed and static in terms of function and structure
- Plasticity and functional recovery
Effects of aging:
How does infant development demonstrate plasticity?
How does this relate to the adult brain?
In infancy: brain experiences growth in the number of synaptic connections it has; peaking around 15,000 per neuron at age 2-3. Twice as many as in the adult
As we age, connections that are rarely used are deleted and frequently used connections are strengthened- synaptic pruning
More stimulations = more synaptic connections = more dense the synapses
- Plasticity and functional recovery
What is functional recovery?
Form of neural plasticity where following damage from trauma the brain is able to redistribute functions normally performed by damaged areas to other undamaged areas
Eg: Romanian orphans
- Plasticity and functional recovery
Give 3 examples of how when environments are enriched or impoverished, it is reflected in brain plasticity
1) Davidson found Tibetan monks had increases gamma waves (coordinate neural activity) when meditating. Shows LT effects
2) Rosenweig brains of enriched rats were different from the impoverished rats, the neurons were larger, the cerebral cortex heavier and thicker
3) Boyke found there’s a natural decline in cognitive function with age. Boyke found 60 year olds had increased grey matter in the visual cortex when learning to juggle. It’s decreased when they stopped
- Plasticity and functional recovery
Explain Maguire’s (2000) study: what was the aim, method, results?
Studied the brains in London taxi drivers and found significantly more volume of grey matter in the posterior hippocampus than in a matched control group.
This part of the brain is associated with the development of spacial and navigation skills in humans and animals
London cab drivers must take a test called ‘the Knowledge’ which assesses their recall of the city streets and possible routes
Maguire used 16 healthy right handed males who were taxi drivers compared to non 50 healthy right handed males who were not taxi drivers. An MRI was used to detect changes in the structure of the brain as a result of experience
The results showed the taxi drivers had larger posterior (back) hippocampus compared to the controls that had a larger anterior hippocampi compared to taxi drivers
Data is only correlational
- Plasticity and functional recovery
Name 2 other studies that are consistent with the findings of Maguire.
Draganksi – imaged brains of medical students 3 months before and after their final exams. Learning-induced changes were seen to have occurred in the posterior hippocampus and parietal lobe, presumably as a result of studying for exams
Mechelli – found a larger parietal cortex in the brain of people who were bilingual compared to matched monolingual conditions
- Plasticity and functional recovery
How does functional recovery suggest plasticity?
- Plasticity and functional recovery
Functional recovery: How does neural reorganisation support plasticity?
Healthy brains may take over the functions of those areas that are damaged, destroyed or even missing (neural reorganisation)
Neuroscientists suggest that is process can occur quickly after trauma (spontaneous recovery) and then slow down after several weeks or months. At this point the individual may need rehabilitate therapy
- Plasticity and functional recovery
Functional recovery: How can neural reorganisation occur?
Recruitment of homologous areas is when a homologous (similar) area of the brain on the opposite side is used to perform a specific task
One example would be Broca’s area was damaged (usually on the left side of the brain) the right side equivalent would carry out the functions (JW case study
After time,
- Plasticity and functional recovery
What is neurogenesis?
Brain is able to retire and reorganise itself by forming new neurons
- Plasticity and functional recovery
How might secondary neural pathways be involved in functional recovery?
The brain doing neurogenesis and forming new synaptic connections close to the area of damage. Secondary pathways are activated to enable functioning to containers, often in the same ways as before (Doidge 2007)
- Plasticity and functional recovery
Name 3 structural changes related to plasticity.
1) Axonal sprouting: growth of new nerve endings which connects with other undamaged nerve cells to form new neural pathways
2) Reformation of blood vessels
3) Denervation super-sensitivity: axons become more responsive to compensate for the loss of adjacent neurons
- Plasticity and functional recovery
2 strengths
P: empirical support from studies, which provides strong evidence to support that the brain can undergo structural changes in response to environmental demands.
Eg: Maguire et al. (2000) used MRI scans on London taxi drivers and found that their posterior hippocampal volume was significantly larger than that of a control group, correlating with the length of time spent as a taxi driver.
Ex: This supports neuroplasticity, showing the hippocampus adapts to spatial navigation demands. The brain’s structural flexibility reinforces how experience shapes neural architecture.
L: Such empirical evidence strengthens the validity of neuroplasticity theory, demonstrating its real-world relevance and application.
P: strongly supported by empirical evidence that shows how the brain can change its structure in response to environmental stimuli.
Eg: Rosenzweig et al. (1972) placed rats in either impoverished or enriched cages for 30-60 days and conducted post-mortem studies. They found that rats in enriched environments (EC) developed a heavier and thicker brain cortex, with the frontal lobes being heavier and showing more acetylcholine receptors.
This supports neuroplasticity, showing brain changes due to stimulation. While animal-to-human generalisation is debated, similar findings in humans reinforce its reliability.
L: This evidence strengthens neuroplasticity theory, highlighting the brain’s adaptability to environmental influences.
- Plasticity and functional recovery
limitation
P: A limitation of the brain’s ability to recover from injury is its dependence on age, with younger individuals experiencing better outcomes.
Eg: Plata et al. (2008) investigated the impact of age on recovery from traumatic brain injury (TBI). They found that younger patients had a higher likelihood of achieving a better recovery compared to older individuals. The study showed that younger brains exhibit more robust neuroplasticity, allowing for more effective reorganization and compensation for lost functions.
Ex: This supports the concept of cognitive reserve, which is greater in younger individuals. As age increases, the brain’s ability to form new connections declines, making recovery more difficult.
L: This research highlights age as a crucial factor in functional recovery from brain injuries.
- Ways of studying the brain
4 methods of studying the brain
-fMRI (functional magnetic resonance imaging)
-EEG’S
-ERP’S (event related potentials)
-Post mortem examinations
- Ways of studying the brain
Explain the 2 types of resolution that are important for imaging
1) spatial resolution: refers to the smallest feature (or measurement) that a scanner can detect. Greater spatial resolution allows psychologists to discriminate between different brain regions with greater accuracy
2) temporal resolution:
the accuracy of the scanner in relation of time or how quickly the scanner can detect changes in brain activity
How many scans your taking in a period of time
- Ways of studying the brain
How does fMRI work?
Based on neurovascular coupling of neural activity and blood oxygenation
Changes in blood oxygenation and deoxygenation
Deoxygated area = more activate area
Neural vascular coupling between synaptic transmission of the neural response and the BOLD response
- Ways of studying the brain
Strengths of fMRI
High spatial resolution: can distinguish different brain areas and regions well
Non invasive: no use of radioactive tracers unlike PET
- Ways of studying the brain
Limitation of fMRI
- low temporal resolution of approx 0.8 secs
- expensive so potentially decreases sample size so lowers reliability
- indirect measure of neural activity, not causational
- movement artifacts can disrupt image
- accessibility eg: no pacemakers or metal or tattoos or pregnant women due to strong magnetic field
- Ways of studying the brain
What are EEG’s
Measures the electrical activity of scalp electrodes while the subject is at rest
Electrode caps, with different configurations, higher spacial resolution with more number of electrodes on cap
- Ways of studying the brain
What is the basis of the EEG signal
What’s the 4 types of EEG waves and how do they differ
Alpha
Delta
Theta
Beta
- Ways of studying the brain
Advantages of EEG’s
- high temporal resolution
- non-invasive
- low cost: can have a higher sample size
- portable: accessibility for more participants for example; can bring to the patient whoch helps patients who are severely ill, old or antisocial p
- Wider range of populations eg: can use anyone as all you need to do is put a cap on the: contributed to sleep studies
- Direct measure As you’re just measuring the neural levels and activity
- Ways of studying the brain
Limitations of EEG
Low spatial resolution
Susceptible to artefacts
Limited to surface activity: can only measure the 3mm cerebral cortex, so you can pick up some activity from other brain regions but don’t know where the activity/signals are coming from, making it difficult to interpret and therefore harder to diagnose or make conclusions
Requires skilled technicians
- Ways of studying the brain
What are ERP’s
event-related potential (ERP’s)
Cognitive or sensory situations
Very similar to EEG but Averaged and time locked
Averaged and time locked response to a stimulus
They isolate specific neural responses associated with sensory, cognitive and motor events
They use a statistical averaging technique
Triggered by a cognitive or sensory stimulus
- Ways of studying the brain
Advantage of ERP’s
gh temporal resolution (same as EEG’S)
Non invasive
Relatively low lost
Sensitive to cognition
- Ways of studying the brain
Limitatioms of ERP’s
Low spatial resolution
Low signal-to-noise ratio and that’s why you need to use averages to cancel out the noise
9: Ways of studying the brain
Advantages of post-mortem research
Highly detailed analysis – molecular level, microscopic so can have high spacial resolution
Access to human tissue
Validate imaging data – used to agree with data from imaging studies
Identify disease mechanisms
9: Ways of studying the brain
Limitations of post-mortem research
Limited availability – majority comes from accidents and diseases that killed.
This creates a selection bias
Time-dependant changes – can cause artifacts as the brain tissue dies after death
Ethical considerations – always need doner or next of kin consent, should we be taking brains from dead people
No temporal resolution
- Circadian rhythms
What are biological rhythms
Cyclical patterns within biological systems
- Circadian rhythms
What’s the Frequency of:
1) circadian
2) infradian
3) ultradian
1) circa = around dian=day
2) lasts longer than one day
3) more than one per day
- Circadian rhythms
What are endogenous pacemakers?
Internal (endo) mechanisms that govern biological rhythms eg: pineal gland
Internal biological clocks
- Circadian rhythms
What are exogenous zeitgebers?
External (external) mechanisms that govern biological rhythms eg: light/dark
‘Time givers’
External influences
- Circadian rhythms
What is the relationship between endogenous pacemakers and exogenous zeitgebers?
All organisms have biological rhythms which are governed by endogenous pacemakers and entrained by exogenous zeitgebers.
- Circadian rhythms
What is the sleep wake cycle
Sleep wake cycle is a free running cycle by an endogenous pacemaker working as a body clock
- Circadian rhythms
What is the biological basis for the sleep-wake cycle?
Superchiasmatic Nucleus is the endogenous pacemaker that controls our sleep wake cycle.
SCN is in the hypothalamus.
When the optic nerves from the eye cross over, it gets stimulated by light that penetrates our closed eye lids
SCN recieves info about light and dark directly from the eye retina so light is the exogenous zeitgeber in the sleep/wake cycle
- Circadian rhythms
What role does the pineal gland play?
What is the role of melatonin?
The pineal gland increases the production of melatonin which we know induces sleep
Sunlight in the morning stops the production of melatonin. Increasing cortisol which increases wakefulness.
SCN -> sends messages to pineal gland -> dark – night = increases melatonin -> induces sleep
- Circadian rhythms
What is the role of homeostasis
Maintenance of constant internal environment
It controls (along with the circadian rhythm) sleeping and wakefulness
When an individual has been awake for a long time, homeostasis tells the body that there’s a need for sleep increases throughout the day, reaching its maximum in late evening
- Circadian rhythms
How is body temp a circadian rhythm
It’s lowest (36°) at 4:30am and highest (38°) at 6pm
Sleep occurs when core temp begins to drop, it rises during last few hours of sleep promoting a feeling of alertness in the morning
- Circadian rhythms
Micheal Siffres study
Aim: investigate the human body’s natural circadian rhythms in the absense of external cues
Procedure:
-isolated himself Ina cave for 6 months, away from natural light, clocks, sunlight.
Controlled environment including temp and humidity
- he recorded his sleep-wake cycles, body temp and psychological state, while researchers monitored with activities remotely
Findings:
His cycle extended to 25 hours, so each ‘day’ lasted an hour longer than the natural 24 hour cycle so his sleep and waking times drifted later each day
Conclusion:
The circadian rhythm is naturally slightly longer than 24 hours
External cues like natural light rest the internal clock to align with the 24 hour day.
- Circadian rhythms
Other evidence for extended sleep wake cycles in the absence of external light
Aschoff and Wever convinced p’s to spend 4 weeks in WW2 bunker deprived of light
All but 1 ppt displayed a circadian rhythm of 24-25 hours the other extended to 29 hours
Researchers sped up the clocks
- Circadian rhythms
What’s desynchronisation and how does it occur wit sleep
Occurs when individuals internal body clock is out of sync with the external environment
Jet lag:
- Caused by travelling across several time zones within several hours
- Internal clock (SCN) isn’t synchronised with the day time-night time rhythm at the place of arrival
- Social cues are involved, adapting to local times for eating and sleeping, entraining circadian rhythms
- Jet lag causes insomnia, fatigue, irritability, poor concentration
- Circadian rhythms
Describe Ralph’s study on sleep wake cycle in humans
Bred a group of hamsters to follow 20 hour cycle
SCN cells were removed and transplanted into brains of rats
Rats adapted to the 20 hour cycle
- Their Brian’s were transplanted with SCN cells from 24 hour cycle
- Cells from SCN were removed from rats with the 24 hour cycle of neural activity persisted in the isolated cells
- Suggests circadian rhythms were primarily controlled by evolutionary determined biological structures
- Circadian rhythms
What experimental biological evidence is there for sleep-wake cycles existing outside the body?
Yamasaki
Found isolated lungs and livers and other tissues grown in a lab still persist in showing circadian rhythms
Suggests cells are capable of amounting a circadian rhythm even when they’re not under control of any brain structures that most boldly cells are tuned into following a daily circadian rhythm
8/16 marker hasn’t come up before:
- Circadian rhythms
Strength of circadian rhythms
P: Evidence from animal studies supports the SCN as a key endogenous pacemaker in regulating the sleep-wake cycle.
Eg: DeCoursey et al. (2000) destroyed SCN connections in 30 chipmunks and observed them for 80 days in their natural habitat. Their sleep-wake cycles disappeared, and many were killed by predators, likely due to increased vulnerability while awake.
Ex: This supports the SCN’s role in maintaining circadian rhythms, particularly the sleep-wake cycle. Observing chipmunks in their natural environment enhances ecological validity, making findings more applicable to real-world settings.
L: This research strongly validates the SCN’s role in circadian regulation.
8/16 marker hasn’t come up before:
- Circadian rhythms
Limitations of circadian rhythms
P: Siffres cave study into sleep wake cycle has methological issues
Eg: lack of control as he used artificial light when im the cave. Which could’ve confounded the results as other research has shown circadian rhythms can be adjusted as a result of dim lighting
Ex experimenter bias, influencing results of study
L: reduces the interval validity, impact of extraneous variables means it’s hard to isolate the effect of the IV on the DV, through this is somewhat mitigated by replication from other studies
P: A limitation of the argument that light is the main exogenous zeitgeber for the sleep-wake cycle is that temperature may play a more significant role.
Eg: Buhr et al. (2010) found temperature fluctuations regulate cellular timing, activating or deactivating tissues and organs. They suggested light levels are converted into neural signals that adjust body temperature.
Ex: As body temperature follows a 24-hour circadian rhythm, even small changes strongly influence biological clocks. This challenges the idea that light is the sole external zeitgeber, highlighting the role of multiple factors in regulating circadian rhythms.
- Infradian rhythms
What is an infradian rhythm? Give an example, with details
Biological rhythm a which is governed by a cycle which lasts more than one day
Menstrual cycle and seasonal affective disorder
- Infradian rhythms
Describe the sequence of the menstrual cycle
28 day cycle
2 phases: Luteal phase and Follicular phase
Luteal: progesterone helps the womb lining to grow thicker to prepare for embryo implantation.
Follicular: rising levels of oestrogen causes ovary to develop and ovulate
- Infradian rhythms
Describe McClintock and Stern study
Aim: investigate whether the menstrual cycle is influenced by pheromonal secretions from other women
Procedure:
29 female uni students, not on birth control
Design: quasi
They inhaled secretions from the armpits of the women who were about to ovulate
Findings:
68% of the participants found that their menstrual cycle had aligned (synchronised) with that of their pad donor
Conclusion:
the researchers concluded that synching of the menstrual cycle has evolutionary advantages
If all the women in one tribe/clan fall pregnant at the same time there are lots of people on hand to help with childcare
- Infradian rhythms
What’s seasonal affective disorder
A depressive disorder which has a seasonal pattern of onset, and is described and diagnosed as a mental health disorder by DSM-5
SAD tends to hit people during the winter months when the days are darker and longer
Symptoms: persistent low mood
- Infradian rhythms
What’s a yearly cycle called
Circannual rhythm
- Infradian rhythms
What is a potential mechanism for seasonal affective disorder?
During winter months more melatonin is secreted from the pineal gland which may result in higher levels of depression or a generalised low mood
Serotonin is implicated in the sleep-wake cycle (it has been linked to melatonin production) so disrupted levels of this neurotransmitter is likely to lead to imbalances in mood
- Infradian rhythms
Treatment for SAD
SSRI’s
Light therapy treatment
- Infradian rhythms
2 strengths of infradian rhythms
P: menstrual cycle is influenced by exogenous zeitgebers is supporting empirical evidence from a case study.
Eg: Reinberg reported a women who spent 3 on this isolated in a cave with minimal light, only a small lap. During her period, her menstrual cycle shorted from 28 days to 25.7 days
Ex: suggests the reduction in light exposure, a key exogenous zeitgeber
, directly influenced the length of her menstrual cycle.
C: methodological Limitatioms of study – reliance on a single ppt and lack of controls during time in cave eg: stress, dietary changes, temperature
L: provides evidence supporting the idea that external environment factors can significantly impact infradian rhythms which increases validity but should be treated with caution as it’s a case study
P: evidence for infradian rhythms, such as the menstrual cycle, is that they play a significant role in regulating human behavior, particularly in relation to sexual preferences.
Eg: Penton-Volk conducted research showing that omen during their least fertile stage preferred men with more feminine faces, and in their most fertile stage preferred men with more masculine face
Ex: suggests women’s sexual behaviour
- Infradian rhythms
Limitation
P: A limitation of early menstrual cycle synchronization research, such as McClintock’s studies, is the lack of control over confounding variables.
Eg: Factors like stress, diet, physical activity, and light exposure were not accounted for, making it unclear whether observed synchrony was due to pheromonal influence or coincidence.
Ex: This weakens internal validity, as uncontrolled variables may explain the results. Additionally, reliance on self-reported data introduces bias, further questioning accuracy.
L: The absence of rigorous controls casts doubt on these findings, undermining the validity of the theory.
- Ultradian rhythms
How many stages of sleep are there?
5
stage 1-4: NREM
stage 5: REM
- Ultradian rhythms
Over what time frequency do they repeat?
5 stages that all together span over 90 mins approx and repeat throughout sleep
- Ultradian rhythms
Describe the features of Stages 1 and 2
Stages 1 and 2 are known as the sleep escalator
At this stage of sleep, it is easy to wake the sleeper; they are in ‘light sleep’
Slow and rhythmic alpha waves (seen via brainwaves which can be tracked using EEG) are the first sign of sleep
Sleep spindles occur more regularly during stage 2 sleep
Theta waves show that the person has gone into a deeper sleep
- Ultradian rhythms
Describe the feature of Stages 3 and 4
Stages 3 and 4 consist of the delta waves of deep sleep
Delta waves are slow and deep, with greater amplitude
At this stage of sleep, it is very difficult to wake the sleeper: it may take some time for them to fully wake up during stage 3/4 sleep
- Ultradian rhythms
Describe the feature of Stages 5
Stage 5 is REM sleep, the stage in which dreaming occurs according to research
The central nervous system is ‘cut off’ (effectively paralysing the body) as dreaming occurs - thought to prevent people from acting out their dreams
REM stands for ‘rapid eye movement’ - the eyeballs are active during this stage of sleep, indicating that dreaming is taking place
Brain activity speeds up during REM sleep, with brainwaves showing similar levels of energy to the awake brain
- Ultradian rhythms
What change occurs over the approximately 5 cycles of the sleep stages?
Sleep staircasing describes progression through the different stages of sleep in an strutted pattern throughout the night
Individuals sleep typically moves from lighter stages to deeper stages and back to lighter stages before entering REM sleep
Resembles a staircase, with each step representing a different stage of sleep
- Ultradian rhythms
Describe the study and findings of Dement & Kleitman (1957)
Aim:
Investigate the relationship between eye movements in REM and non-REM sleep
Procedure:
-Monitored 9 adults for 6-17 nights.
-Their brainwaves was measured on an EEG as they slept in a lab
-They all consumed no caffeine or alcohol as a control
-They were woken at specific intervals during their sleep and asked if they were dreaming and if so, what was the dream about
IV: whether they woke up from REM/NREM
DV: whether they could recall a dream and if so the details
Findings:
-positive correlation between REM sleep and dreaming
-more dreams were recalled in REM (153) than NREM (11)
-ppts could accurately estimate dream duration
-eye movements were strongly related to dream content eg: one said looking up and down at a ladder(vertical)
Conclusion:
REM activity during sleep was highly correlated with the experience of dreaming, brain activity varied according to how vivid dreams were, ps woken during dreaming reported very accurate recall of their dreams
- Ultradian rhythms
How are meal patterns an ultradian rhythm
Follows a 3-5 hour cycles
Influenced by:
-biological basis - tied to body metabolic processes, influencing in blood sugar levels, release of gherlim (stimulates appetite) and insulin (manages blood sugar levels) and laptop (satisfies appetite)
-environmental and social influences - times of meals can be affected by work schedules, social norms and food availability
- Ultradian rhythms
One strength
P: One strength of understanding ultradian rhythms, such as sleep cycles, is that it helps us grasp age-related changes in sleep patterns.
Ex: research shows slow-wave sleep (vital for growth hormone production) decreases with age.
Van Cauter suggests this reduction may contribute to the physical impairments commonly observed in older adults due to decreased release of growth hormones during sleep
Ex: when slow wave naturally declines with age, interventions like relaxation techniques and medications can enhance this stage, potentially mitigating some age-related health issues.
L: this highlights the practical value of understanding ultradian rhythms as it informs clinical treatments aimed at improving life quality of older adults
8/16 marker hasn’t come up before:
- Ultradian rhythms
2 limitations
P: A key methodological issue in sleep studies is low ecological validity due to artificial lab environments.
Eg: Participants sleep in labs, wired to EEG machines, and restricted from alcohol or caffeine, reducing mundane realism and potentially disrupting natural sleep.
Ex: This setting may introduce demand characteristics, leading to inaccurate dream recall due to annoyance, a desire to sleep sooner, or embarrassment. Small, demographically limited samples further reduce generalisability.
L: While sleep studies offer valuable insights, their findings may not fully reflect real-world sleep patterns or apply broadly across populations.
P: A limitation of studying the sleep cycle is the significant individual differences between people.
Eg: Tucker found large variations in sleep stage duration, particularly in stages 3 and 4, which are essential for deep sleep and restoration.
Ex: These differences are likely influenced by biological factors such as genetics, age, and health, making them difficult to control or predict in research.
L: This variability challenges a nomothetic approach, suggesting generalised findings may not apply to everyone, limiting the applicability and generalisability of sleep research.
What’s the resting potential
-65mV (also called polarised state)
