Biopsychology Flashcards
(154 cards)
1
Q
What is the nervous system?
A
-a specialised communication system made up of a network of cells called neurons
-based on electrical and chemical signals
2
Q
two main functions of the nervous system
A
-to collect process and respond to information in the environment
-to co-ordinate organs + cells in the body
3
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What are the subsystems of the nervous system?
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-the central nervous system
-the peripheral nervous system
4
Q
the CNS
A
-made up of the brain and spinal cord
-the brain receives info from sensory receptors (eyes, ears, skin etc) about the environment
- brain then sends this information to the muscles and glands of the body through the spinal cord
5
Q
The brain
A
-divided into 2 hemispheres
-responsible for all conscious awareness
-the cerebral cortex(outer layer of the brain) is responsible for higher-level processes including language, memory, emotion, intelligence, personality etc.
6
Q
4 main areas of the brain
A
-cerebrum= the largest part of the brain + 4 lobes with different primary functions i.e the frontal lobe which is involved with thought and the production of speech
-cerebellum= controls motor skills + balance i.e coordinating muscle movement
-diencephalon= contains the thalamus which directs impulses to the relevant area of the brain and the hypothalamus which regulates body temp, release of hormones, hunger + thirst
-the brain stem= regulates automatic functions i.e breathing, motor and sensory neurones pass these impulses through CNS
7
Q
The spinal cord
A
-role is to relay info between the brain and the rest of the body
-an extension of the brain
-connected to different parts of the body by pairs of spinal nerves, which connect with specific muscles and glands(PNS)
-contains neurons/nerve cells that enable us to perform simple reflexes i.e pulling your hand away from a hot plate
8
Q
the PNS
A
-transmits messages, via millions of neurons(nerve cells), to and from the CNS
-divided into autonomic nervous system and the somatic nervous system
9
Q
the ANS
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-governs involuntary actions in vital organs and glands i.e breathing rate, digestion, stress responses
-divided into parasympathetic and sympathetic nervous systems
-only motor neurons are involved
-control centres are in the brain stem
10
Q
the SNS
A
-controls skeletal muscle movement
-involved in reflex + voluntary actions
-both sensory AND motor neurons are involved
11
Q
the syNS and the psNS
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-regulate the same organs but have opposite effects due to the neurotransmitters in each division–} either excitatory(which increases activity) or inhibitory(calming effect)
-syNS prepares the body for flight or fight= sends messages to every organ and gland within the body, preparing for rapid action when the individual is under threat
-the PSNS relaxes the body once the emergency has passed
12
Q
What is the endocrine system?
A
-instructs glands to release hormones in the bloodstream–} hormones are carried towards target organs with a specific receptor in the body
-acts slower than the nervous system but had widespread effects
13
Q
Hypothalamus
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-regulates internal body temp
-controls the pituitary gland + links the NS to the endocrine system
14
Q
Pituitary gland
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-‘master gland’–} control the release of hormones from other glands i.e oxytocin(love hormone)
15
Q
Pineal gland
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-produces the hormone melatonin, responsible for making you sleepy
16
Q
Thyroid + Parathyroid gland
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-secretes thyroxine to regulate metabolism
-affects metabolic rates therefore affecting growth
17
Q
Thymus
A
-serves a vital role in the training and development of T-lymphocytes (type of white blood cell involved in the immune system)
18
Q
Pancreas
A
-controls blood glucose levels with the release of insulin/glucagon
19
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Adrenal glands
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-regulates metabolism + maintains balance of salt and water in the body
-produces adrenaline, involved in the stress response
20
Q
Ovary (in females)
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-responsible for producing hormones in sexual development in females i.e oestrogen
21
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Placenta (during pregnancy)
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-provides O2 + nutrients to your growing baby + removes waste products from baby’s food
22
Q
Testes (in males)
A
-responsible for providing hormones in sexual development in males i.e testosterone
23
Q
Hormones
A
-secreted into the bloodstream and affect any cell in the body that have a receptor for that particular hormone
-i.e thyroid gland produces thyroxine–} increases heart rate + metabolic rates which affects growth rates
24
Q
What is the fight or flight response?
A
-evolved as a survival mechanism= enabled humans and animals to react quickly
-upon sensing a threat, the amygdala becomes mobilised–} associates sensory signals with emotions i.e fear or anger
-this sends a distress signal to the hypothalamus which communicates to kickstart the response
25
Fight or flight response
-when a stressor is perceived, the hypothalamus activates the pituitary gland
-this triggers activity in the sympathetic branch of the ANS
-ANS changes from its normal resting state to the physiologically aroused sympathetic state
26
Adrenaline
-released by the adrenal medulla(part of the adrenal gland near the kidney) into the bloodstream
-triggers physiological changes in the body:
- increased heart rate
- slow digestion in the gut
- inhibits salivary production in salivary glands
- triggers release of blood glucose (to supply energy)
- inhibits urination by relaxing the bladder (takes up less energy)
- dilates pupils (take in more light to see)
- dilates bronchi in the lungs (more O2)
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Immediate and automatic
-physiological changes are an acute and automatic response in the body
-i.e increased heart rate + breathing rate, dilated pupils
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Parasympathetic action
-returns the body to its resting state
-works antagonistically to the sympathetic system
-i.e stimulates digestion + saliva production etc
-rest and digest response
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Evaluating fight or flight:
Gender bias
-Taylor et al (2000) suggested that, for women, behavioural responses to stress are 'tend and befriend' rather than fight or flight--} protect themselves and their young through nurture and form protective alliances with other women
-different way of coming because their responses are based around being the primary caregiver of their offspring
-produce higher levels of oxytocin than men
-Lee and Harvey (2012) found that the SRY gene, found exclusively on the male Y chromosome, results in the fight or flight response
HOWEVER Von Dawans et al found that acute stress could lead to 'tend and befriend' for both men AND women i.e human connection during 9/11--} protective nature of human social relationships
30
Evaluating fight or flight:
weak application
-the physiological responses associated with fight or flight are not adapted to modern life
-repetitive stress response leads to a constant raised BP caused by the SyNS
-this can lead to physical damage in blood vessel + eventually heart disease
31
Evaluating fight or flight:
limited explanation
-Gray(1998)= the first phase of reacting to a threat is to avoid confrontation by FREEZING
-the adaptive advantage is that freezing focuses attention and allows you to look for new information in order to make the best response for that particular threat
32
What is a neuron?
-aka a nerve cell
- a specialised cell designed to transmit information to other neurons, muscle, or gland cells through electrical + chemical signals
- over 100 billion neurons in the body – of which 80% are located in the brain
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3 main types of neurons
-sensory neurons= carry messages from the PNS to the CNS, have long dendrites and short axons
-relay neurons= connect the sensory and motor neurons, have short dendrites and axons
-motor neurons= connect the CNS to effectors i.e muscles + glands, have short dendrites and long axons
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The structure of a neuron: cell body
-has a nucleus which carries the genetic material of the cell
-determines what type of cell it is
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The structure of a neuron:
dendrite
-protrude from the cell body
-carry nerve impulses from neighbouring neurons towards the cell body
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The structure of a neuron:
axon
-carries the impulses away from the cell body down the length of the entire neuron
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The structure of a neuron:
myelin sheath
-fatty layer that covers the axon
-protects the axon and speeds the electrical transmission of the impulse
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The structure of a neuron:
Nodes of Ranvier
-gaps that are segmented in the myelin sheath by speeding up the transmission of the impulse by forcing it to 'jump' across the gaps along the axon
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The structure of a neuron:
axon terminal buttons
-communicates with the next neuron in the chain across a gap known as the synapse
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Where are the neurons located?
-cell bodies of motor neurons may be in the CNS but the long axons form part of the PNS
-sensory neurons are located in the PNS, in clusters(ganglia)
-Relay neurons make up 97% of all neurons and most are found within the brain + visual system
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Electrical transmission
-a neuron is negatively charged when in a resting state within a cell compared to the outside
-when a neuron is activated by a stimulus, the inside of the cell becomes positively charged--} causes action potential to occur
-creates an electrical impulse that travels down the axon towards the end of the neuron
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How do neurons communicate with each other?
-neurons communicate with each other in groups called neural networks (not physically connected)
-signals WITHIN neurons are transmitted electrically but signals BETWEEN neurons are transmitted chemically across the synapse (gap between 2 dendrites)
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Neurotransmitters
-chemical messengers in the NS that can trigger an electrical impulse--} do this by diffusing across the synapse to the next neuron in the chain
-around 30 different types in the brain
-own specific molecular structure that fits perfectly in a receptor site(lock and key)
-have specialist functions
-direction of travel is one way(pre to postsynaptic neuron)
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Why are neurotransmitters needed?
-electrical impulses cannot pass from the axon terminal to the adjacent dendrite
-instead must pass via a chemical messenger
-chemical message is converted back into an electrical impulse once it reaches the postsynaptic receptor site
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4 types of neurotransmitters
-adrenaline= produced in stressful situations, increases heart rate + blood flow to increase awareness(causes excitation)
-noradrenaline= affects attention and responding actions in the brain, contracts blood vessels
-dopamine= feelings of pleasure, addiction and motivation
-serotonin= contributes to well being and happiness, helps sleep cycle + digestive system regulation(causes inhibition)
46
Excitatory neurotransmitters
-when detected by the post-synaptic receptors, they make the electrical charge more positive(depolarisation)
-create an excitatory post synaptic potential(EPSPs)--} formation of a new action potential is more likely= 'on switch'
47
Inhibitor neurotransmitters
-when detected by the post-synaptic receptors, they have a negative charge on the post-synaptic neuron(hyperpolarisation)
-results in an inhibitory post-synaptic potential(iPSPs)---} formation of a new action potential less likely= 'off switch'
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Summation
-net effects of all the excitatory + inhibitor neurotransmitter summed determines whether the postsynaptic cell is fired
-the net effect has to reached(excitatory input> inhibitory input)
-if the threshold is reached, then the new action potential is formed and then travels down the next axon
49
Synaptic transmission
-an action potential(electrical impulses) travels down the axon and triggers the synaptic vesicle to release neurotransmitters
-these chemically diffuse across the synapse cleft + bind to postsynaptic receptor sites of the dendrites on the next neuron
-neurotransmitters that don't bind to the next receptor site are reabsorbed by the presynaptic neuron via a transport protein
-any left over neurotransmitters are broken down by enzymes
-synaptic vesicles are replenished with new + re-used neurotransmitters
50
Localisation vs holistic theory
-it was believed that all parts of the brain were involved in processing of thought and action before investigations in the 19th century
-Broca and Wernicke argued that separate parts of the brain perform different tasks in different parts of the body(cortical specialisation)
-i.e if a specific area of the brain becomes damaged, it may cause damage in the part of body it is associated with
51
Cerebral cortex
-outer layer of both hemispheres
-divides into 4 lobes, each associated with different functions
-**lateralisation**= 2 hemispheres are functionally different and contra lateral
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Frontal lobe
-responsible for cognitive functions i.e attention, thinking, memory + learning
-also processes the autonomic and emotional processes
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The motor cortex
-located in the frontal lobe in both hemispheres of the brain
-responsible for voluntary movement in the opposite side of the body
-damage to this may result in loss of control of fine movements
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Broca's area
-small area of the **left** frontal lobe
-critical for speech production
-when damaged, patients suffer with Broca's aphasia
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Temporal lobe
-processes auditory information
-helps in understanding of speech and written language and memorising symbolic sounds and words
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The auditory cortex
-located in the temporal lobe in both hemispheres
-analyses speech based info
-sound waves are converted to nerve impulses in the cochlear
-travels to the brain stem for a basic decoding(i.e duration + intensity of sound), then the thalamus which acts as a relay station for processing then to the auditory cortex to be recognised + responded to
-damage may lead to partial/full hearing loss
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Wernicke's area
-back portion of the left temporal lobe
-involved in understanding language
-damage may lead to inability to understand + comprehend language
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Parietal lobe
-mainly concerned with processing physical sensations + coordination with visual and auditory sensations
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The somatosensory cortex
-located in the parietal lobe
-in both hemispheres
-detects sensory info from different parts of the body
-uses info from the skin to produce sensations of touch, pressure, pain + temp and localised this to specific areas
-the amount of somatosensory area in a part of the body relates to the amount of sensitivity in that area
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Occipital lobe
-interprets visual impulses, memorises visual stimuli and helps in colour visual orientation
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The visual cortex
-located in the occipital lobe of the brain
-in both hemispheres
-visual processing in the retina leads to nerve impulses being transmitted to the brain via the optic nerve
-each eye sends info from the right visual field to the left visual cortex and vice versa(cross-wired)
-damage to one side of the brain may lead to blindness in the opposite visual field
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Broca's aphasia
-conducted a post-mortem on a patient named 'Tan' (the only word they could pronounce)
-could understand spoken language but not speak or write his thoughts
-after studying 8 other similar patients, he found that they all had lesions their left frontal hemisphere
-identified the existence of a ‘language centre’ responsible for speech production
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Wernicke's aphasia
-conducted post-mortems on people who had produced fluent, but meaningless speech
-when damaged, people will produce nonsense words (neologisms)
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Evaluating localisation of the brain:
evidence from neurosurgery
-damage of areas of the brain have been linked to mental disorders
-cingulotomy involves isolating a region called the cingulate gyrus , implicated in OCD
-Dougherty et al(2002) reported 44 people with OCD who has undergone a cingulotomy
-a post-surgical follow up after 32 weeks about 30% met successful response to the surgery
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Evaluating localisation of the brain:
evidence from brain scans
-supports the idea of everyday brain functions being localised
-Peterson et al(1988) used brain scans to show how Wernicke's area was active during a listening task + Broca's area during a reading task
-Buckner + Peterson(1996) reviewed long-term memory studies revealed that semantic + episodic memories in different parts of the prefrontal cortex
-objective methods for measuring brain activity have provided scientific evidence for localisation
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Evaluating localisation of the brain:
evidence from case studies
-unique cases of neurological damage support localisation theory
-i.e Phineas Gage lost most of his left frontal lobe when a metal pole passed through his skull
-became quick tempered and rude
-change in his temperament following the accident suggested that the frontal lobe may be responsible for regulating mood
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Evaluating localisation of the brain:
modern psychologists
-Lashley removed of the areas of the cortex in rats that were learning the route through a maze
-the process of learning the route seemed to require every part of the cortex equally
-higher cognitive processes may be distributed more holistically
-Dick and Tremblay= only 2% of modern day researchers believe that language is completely localised to the Broca’s and Werncike’s area
-using FMRIs, it is seen that language production is more holistic than localised; regions in the right hemisphere and subcortical regions in the thalamus are all seen to work together
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What is hemispheric lateralisation?
-some mental processes are specialised to either the right or left hemisphere as they have different functions
-certain behaviours are controlled by one hemisphere rather than the other
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How is the brain contralateral?
-the left part controls the right part of the body and vice versa i.e the motor area
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Left brain functions
-the two main language centres are in the LH: Broca's area in the frontal lobe and Wernicke's area in the temporal lobe
-recognition of words, letters + numbers
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Right brain functions
-controls creativity
-contributes to the emotional context to what is being said
-recognition of faces, places and objects
-produces rudimentary words and phrases
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Visual fields
-each eye receives light from the left visual field and the right visual field(ipsilateral= same sided)
-the LVF of both eyes is connected to the RH and the RVF of both eyes is connected to the LH(contralateral)
-enables the visual areas to compare the slightly different perspective from each eye and aids depth perception
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Evaluating lateralisation: connected brains used as supporting research
-Fink et al(1996) used PET scans to identify which brain areas were active during a visual processing task
-when ppts with connected brains were asked to attend to global elements of a image i.e looking at a whole forest, regions of the RH were more active
-when required to focus on the finer detail, the specific areas of the LH tended to dominate
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Evaluating lateralisation: lack of evidence to suggest a 'dominant side'
-Nielsen et al(2013) analysed brain scans from over 1000 people aged 7-29 and did find that people used certain hemispheres for certain tasks BUT there was no evidence of a dominant left side i.e mathematician's brain vs artists' brain
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Evaluating lateralisation: lateralisation vs plasticity
-lateralisation is adaptive as it enables 2 tasks to be performed at the same time with greater efficiency
-Rogers et al(2004) showed lateralised chickens could find food while watching for predators but 'normal' chickens couldn't
-plasticity could be seen as adaptive as functions can be taken over by non-specialised areas following damage/illness--} language function can 'switch sides'(Holland et al 1996)
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Corpus collosum
-a bundle of 200-300 million nerve fibres that connect the 2 hemispheres and allow them to communicate
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What is a 'split brain' operation?
-severing the connection between the RH and LH by cutting the corpus collosum
-used to reduce epilepsy as electrical activity cannot move from one hemisphere to another
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Sperry's split-brain research: Task 1
-11 patients were studied in a set up where an image could be projected to a ppt's RVF and the same/different image could be projected to a ppt's LVF
-found that ppts could describe image from RVF(left hemisphere) but could not for the LVF(right hemisphere)
-this was due to no language centres in the RH
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Sperry's split-brain research: Task 2
-with objects placed in ppts' right hand(processed by LH), they could describe what they felt and identify it from a list
-with objects in left hand(processed by RH) they could not verbalise its description but could identify it from a list of objects
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Sperry's split-brain research: Task 3
-when a picture was presented to RVF and drawn by right hand(processed by LH), they found it hard to draw with their right hands and it was unclear
-when a picture was presented to LVF and drawn by left hand(processed by RH), their drawings were much clearer(better at visual motor tasks)
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Evaluating split-brain research:
Supporting research(Gazzaniga)
-showed that split brain ppts performed better than connected control ppts on certain tasks i.e identifying the odd one out with objects
-the cognitive strategies in the LH are 'watered down' by the inferior RH in the connected brain(Kingstone et al)
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Evaluating split-brain research: issues with generalisations
-Sperry compared the behaviour of split brain patients with neurotypical control group
-the split brain ppts having epilepsy would go unaccounted for and become a confounding variable
-lower IV could be avoided by control group having epilepsy
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Evaluating split-brain research: Ethics
-operation wasn't done for the purpose of this research--} not deliberately harmed
-all procedures were explained to ppts for full consent
-BUT trauma of the operation may mean the ppts didn't understand the implications of their consent
-were tested over a long period of time which may have been stressful
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What is meant by plasticity?
-has the ability to change/adapt throughout life
-i.e learning new skills, developmental changes, brain injury from direct trauma, indirect brain injuries(strokes etc)
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Synaptic pruning
-frequently used neural pathways become stronger and rarely-used ones are deleted/become weaker
-makes the brain more efficient as it strengthens the connections of neurons which you need to use
-brain is able to constantly adapt to a changing environment, even the adult brain
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Research into plasticity: Maguire et al(2000)
-using MRI scans, the amount of grey matter in the brains of 16 male taxi drivers were compared to 50 men(ctrl)
-posterior hippocampus of taxi drivers were significantly larger than the ctrl group--} area is associated with the development of spatial navigation skills(needed for The Knowledge)
-positive correlation between posterior hippocampus volume and the time spent as a taxi driver
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Research into plasticity: Bezzola et al(2012)
-demonstrated how 40 hours of golf training produced changes in the neural representation of movements in ppts aged 40-60
-using fMRI, the reduced motor cortex activity in the novice golfers compared to a ctrl group was observed, suggesting that neural representation was more effective after training
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Research into plasticity: Draganski et al(2006)
-imaged the brains of medical students 3 months before + after their finals
-leaning-induced changes were seen to have occurred in the posterior hippocampus + the parietal cortex presumably as a result of the learning
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Research into plasticity: Kuhn et al(2014)
-compared a ctrl group with a video game training group that was trained for 2 months (min 30 mins per day) on super mario
-found a significant increase in grey matter in various brain areas including the cortex, hippocampus + cerebellum
-increase wasn't evident in the ctrl group that didn't play
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Evaluating plasticity:
Negative implications
-may have negative behavioural consequences
-Medina et al(2007)--} the brain's adaptation to prolonged drug use leads to poorer cognitive functioning in later life, as well as increased risk of dementia
-Ramachandran and Hirsten(1998)--} 60-80% amputees have been known to develop phantom limb syndrome, thought to be due to cortical reorganisation in the somatosensory cortex that occurs as a result of limb loss
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Evaluating plasticity:
Seasonal brain changes
-seasonal plasticity in response to environmental changes
-i.e evidence that the suprachiasmatic nucleus(SCN) which regulates the sleep/wake cycle shrinks in songbirds during spring + expands throughout autumn (Tramontin and Brenowitz 2000)
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What is functional recovery?
-functions performed by areas of the brain are lost (neuronal cell death)/damaged are performed by un damaged areas of the brain (neuronal reorganisation)
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Axonal sprouting
-the growth of new nerve endings which connect with other undamaged nerve cells to form new neuronal pathways
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Neuronal unmasking
-the brain is able to ‘rewire’ + reorganise itself by forming new synaptic connections
-Wall(1977) suggested we have ‘dormant synapses’ that hold required functions but are blocked and ineffective
-in injury, increased input into the dormant synapses unmasks them, allowing for connections to be activated
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Denervation super-sensitivity
-occurs when axons that do a similar job become aroused to a higher level to compensate for the ones that are lost
-can have the negative consequence of of over sensitivity to messages such as pain
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Recruitment of homologous areas
-homologous areas on opposite sides of the brain can perform specific tasks localised for the other side
-i.e Broca’s area was damaged on the left side of the brain, the right sided equivalent would carry out its functions
-functionality may then shift back to the left wide after a period of time
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Evaluating functional recovery:
Case study support
-Danelli(2013) studied of 14 year old EB, who had a hemispherectomy of the left side of his brain to remove a tumour at 2 and a half years old
-removed the language centres of Broca’s and Wernicke’s areas
-immediately after surgery, EB had for all language ability(aphasia)
-after 2 years, EB had recovered his language ability (had some symptoms like dyslexia)
-researchers noted fMRI’s showed the right hemisphere followed the left
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Evaluating functional recovery:
Real world application
-contributed to neurohabilitation--} understanding that axonal growth is possible has led to new therapies being tried i.e. constraint induced movement therapy (used for people who have suffered a stroke to strengthen motor connections for the affected side)
-medics know when intervention is needed
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Evaluating functional recovery:
influence of education
-level of education may affect recovery
-Schneider et al= the more time people with brain injuries had spent in education, the greater their chances of a disability free recovery(DFR)
-40% of DFRs had more than 16 years of education compared to 10% who had less than 12 years
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What is the purpose of scanning the brain?
-to investigate localisation + determine which parts of the brain do what
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fMRI (functional magnetic resonance imaging)
-works by detecting changes in blood oxygenation and flow—} occurs as result of neural activity in specific parts of the brain
-i.e when an area of the brain is more active it consumes more oxygen which means more blood flow is directed to that area
-produces 3D images(**activation maps**) which show what parts of the brain are involved in a particular process(by measuring what area has the most O2)
-image is produced by the use of strong magnetic fields and radio waves
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What is spatial + temporal resolution
-temporal resolution= image/reading is taken at the same time the task is causing brain activity
-spatial resolution= the image produces is very detailed so minor differences can be spotted
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Evaluating fMRI
:) • has good spatial resolution(images are accurate to 1mm)—} clear picture on localised activity
• unlike PET scans etc, it doesn’t rely on radiation + is virtually risk-free, non invasive
:( • expensive compared to other imaging techniques
• poor temporal resolution—} 5 second time lag behind the image on the screen and the initial firing of neuronal activity(can’t fully represent moment to moment activity)
• uncomfortable for patients like children as they have to stay very still
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EEG scans
-measures electrical activity of the brain via electrodes fixed to a skull cap
-scan recording represents the brainwave patterns that are generated from the action of thousands of neurons—} provides overall account of brain activity
-often used as a diagnostic tool by clinicians as it can detect arrhythmic patterns i.e epilepsy, tumours (slower activity)
-can detect sleep patterns/disorders
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Evaluating EEGs
:) • useful in studying stages of sleep—} -relaxed rhythmic alpha waves when awake and as a person falls into deep sleep it is replaced by lower frequency theta waves and then delta waves.
high frequency + low amplitude beta waves during physiological arousal/REM
• extremely high temporal resolution(can accurately detect activity at 1millisecond)
• diagnosis of conditions i.e epilepsy= random burst of energy in the brain
:( • tend to produce very generalised info(many thousands of neurons)—} can’t pinpoint the exact source of activity
- can’t distinguish between activity originating in different but adjacent locations
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ERPs (event related potentials)
-a way of isolating all the relevant neural responses from EEG data
-uses a statistical averaging technique to filter out all extraneous brain activity and leave only the responses that relate to a specific target stimulus/task
-researcher must conduct many trials of that stimulus and average the responses together—} left with the relevant brainwave for that event or the ERP
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Evaluating ERPs
:) • bring more specificity to the result of EEG data + can eliminate extraneous neural activity (experimentally robust)
• have excellent temporal resolution as they are derived from EEG measurements—} can be used to measure cognitive functions
:( •critics have pointed out the lack of standardisation in ERP methodology between different research studies= makes it difficult to confirm findings
-very hard to eliminate all extraneous material i.e background noise
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Post mortem examinations
-the analysis of someone’s brain after their death
-likely to be those with rare disorder + have experienced unusual deficits in cognitive processes/behaviour i.e Broca conducted study on Tan to locate Broca’s area
-can identify brain structures in memory i.e found lesions in HM’s hippocampus which linked to STM (Annese et al 2014)
-helps us learn more about mental disorders—} Folkai et al(1998) found more dopamine receptors in the left amygdala in the brains of people with schizophrenia
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Evaluating Post mortem examinations
:) • vital in providing foundation to understand key processes in the brain early on i.e Broca and Wernicke establishing links between brain and language before neuroimaging
• helped generate hypothesis for further study and improve medical knowledge i.e HM’s damaged area of the brain was linked to STM
:( • lack of causation= observed damage and the deficits may not be linked + could be due to unrelated trauma/decay
• raise ethical issues of consent= ppts can’t give informed consent + family may have to give permission, cultural variations i.e Islam doesn’t allow donations of body after death
110
What are circadian rhythms?
-biological rhythms that are distinct patterns in the body’s activity and subject to a 24 hour cycle + include physical, cognitive and emotional changes
-governed by:
•**endogenous pacemakers**= internal body ‘clock’
•**exogenous zeitgebers**= external changes in the environment
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The sleep/wake cycle
-recurring pattern of transition between sleep and wake to ensure sufficient rest for mind + body
daylight impacts whether we feel tired or not(exogenous zeitgeber)
-also governed by the suprachiasmatic nucleus(SCN) which lies above the optic chiasm and provides info from the eye about the light(endogenous pacemaker)—} BUT can be reset by exogenous zeitgebers
-SCN detects darkness and instructs pineal gland to secrete melatonin or vice versa
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What would happen if the exogenous zeitgebers are removed?
-the biological rhythm becomes **free running**= based on only endogenous pacemakers and are not affected by exogenous zeitgebers
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Siffre(1962) cave study: APFC
-aimed to study the effects exogenous zeitgebers had on his own biological rhythms
-spend several extended periods of time living in a cave with no natural light(had an artificial lamp)
-after 2 months in the cave he resurfaced in mid-sept thinking it was mid-august
-found that his ‘free running’ biological rhythm was around 25 hours(not big change)
-concluded that endogenous pacemakers had a bigger impact
114
Aschoff + Rutger(1976) study
-placed a group of ppts in a WW2 bunker for 4 weeks deprived of natural light
-all ppts displaced circadian rhythm between 24 and 25 hours except one(29 hours)
-suggests that endogenous pacemakers control the sleep/wake cycle in the absence of light
115
Folkard et al(1985)
-studied 12 ppts who lived in a dark cave for 3 weeks
-he manipulated the clocks so only 22 hours passed in a day
-only one of the ppts could comfortably adjust to the new regime
-suggests the existence of a strong free-running circadian rhythm that cannot easily be overridden by exogenous zeitgebers
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Evaluating circadian rhythms:
Real life application- shift work
-provides understanding of the consequences when circadian rhythms are disrupted(desynchronisation)
-Boivin et al(1996)= night shift workers in a period of reduced concentration around 6am experience a circadian trough—} makes mistakes more likely
-Knutsonn 2003= shift workers are 3x more likely to develop heart disease than working more typical patterns
HOWEVER these studies use correlational methods so it is difficult to establish whether desynchronisation is the cause of the negative effects
-Solomon(1993) concluded that high divorce rates in shift workers was due to the strain of deprived sleep + missing out on family events
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Evaluating circadian rhythms:
Real life application- Medical treatments
-has improved medical guidelines relating to the time of medications
-led to the field of chrono therapeutics(how medical treatments can be administered in a way that corresponds to a person’s biological rhythms)
-i.e heart attack medication taken last thing at night reduces blood platelet activity to reduce risk of heart attack(Bonten et al 2015)
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Evaluating circadian rhythms:
poor control in studies
-Siffre used artificial light in his study, which is still an exogenous zeitgeber
-this is shown by Zeisler et al (1999)—} altered ppts’ circadian rhythms down to 22 hours + up to 28 hours using artificial light
-suggests that artificial light is a confounding variable
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Evaluating circadian rhythms:
led to discussions about the structure of school days
-many researchers suggest that the school day starts a few hours later as teen circadian rhythms end and begin later than adult—} neuroscientists suggest that teen rhythms typically begin 2 hrs later(hormonal influence)
-supported by Kelley(2010)= 106 schools where students started at 10am rather than 9 over a 2 year period, academic results + social relationships improved, illness decreased
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What are infradian rhythms?
-biological rhythms that takes longer than 24 hours to complete
-i.e the menstrual cycle, seasonal affective disorder
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The menstrual cycle
-endogenous cycle BUT can be affected by exogenous factors
-monthly changes in hormone levels regulate ovulation
-starts from first day of period to the day before her next period
-roughly 28 days(varies 24-35)
-**ovulation**= rising levels of oestrogen cause ovary to develop an egg and release it
-progesterone helps the womb lining then grow thicker, ready for pregnancy
-**menstrual cycle**= if the egg isn’t fertilised, it gets absorbed into the body + the womb lining sheds and leaves the body
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Syncing periods: McClintock and Stern(1998) APFC
-aimed to demonstrate how menstrual cycles may synchronise as a result of pheromones
-studied 29 women with irregular periods + gathered pheromones from 9 of them who were all at different stages of their cycles
-gathered via a cotton pad under the armpit for 8 hours, which was treated with alcohol and frozen
-pads were rubbed on the top lip of the other ppts to transfer pheromones
-found that 68% of women experienced changes that synced them with odour donors
-concluded that length of cycles could change due to sharing pheromones between women
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Evaluating the menstrual cycle:
evolutionary basis
-synchronisation may be explained by natural selection
-advantageous for women within the same social group to menstruate and become pregnant at the same time—} babies who has lost their mothers would have access to breast milk + increases their survival rate
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Evaluating the menstrual cycle: methodological issues
-McClintock and Stern’s study was naturalistic and performed over a long time—} hard for confounding variables to be controlled i.e diet + stress levels(known to have an effect on the cycles too)
-Trevathan et al(1993) failed to find any evidence of menstrual synchrony in all female samples= hard to replicate
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Evaluating the menstrual cycle:
Research has a lack of cause and effect
-McClintock and Stern’s study has been criticised for being a correlation between the pheromones and menstrual cycles
-little investigation into other factors + their impact on the menstrual cycle in comparison to pheromones
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What is seasonal affective disorder(SAD)?
-depressive disorder patterned by a seasonal onset + diagnosed as mental disorder in DSM- 5
-symptoms include a persistent low mood, lack of activity and interest in life
-triggered in the winter months when the number of daylight hours are shortened(**circannual rhythm**= a yearly cycle)
-can be classed as circadian rhythm due to disruption of sleep/wake cycle + links to darkness
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The role of melatonin in SAD
-suspected of being part of the cause of SAD—} during the night, the pineal gland secretes melatonin until dawn, where there is an increase of light
-during winter, the lack of light in the morning increases the secretion of melatonin for a longer period of time
-melatonin is thought to have a knock off effect for the production of serotonin(neurotransmitter that is low in people with depression)
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Evaluating SAD:
real world application
-has helped develop phototherapy= a box which simulates very strong light to rest the body’s internal clock
-studies show this helps reduce the effects of SAD in about 80% of people(Sanassi 2014)
-phototherapy is preferred over antidepressants to treat SAD because ur is regarded as safe
HOWEVER
-30% of those receiving a placebo treatment stated that they felt a decrease in symptoms
-Rohan et al(2009) recorded a relapse of 46% over successive winters compared to 27% in control group of CBT patients
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Evaluating lateralisation: Alternative explanations
-Lashley suggested that both hemispheres + all areas of the brain are equally able to perform a task and work together
-especially in more complex cognitive processes i.e learning + conscious thought
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What are ultradian rhythms?
-biological rhythms that have a frequency of 24 hours
-has multiple cycles in those 24 hours i.e stages of sleep
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Stages of sleep
-there are 5 stages and they last 90 mins all together
-each stage has different durations and brain wave activity(can be measured by EEGs)
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stages 1 and 2
-light sleep
-1: muscle activity slows down + brain generates alpha waves(high frequency + low amplitude)
-2: breathing & heart rate slows down + alpha waves continue BUT random changes in pattern called sleep spindles
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stages 3 and 4
-deep sleep/slow wave sleep(SWS)
-brain generates delta waves(lower frequency + higher amplitude)
-difficult to wake someone at these stages
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stage 5
-REM(rapid eye movement)
-body is paralysed but brain activity closely resembles brain awake
-brain produced theta waves
-eyes move around + dreams are most often experienced here
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Evaluating ultradian rhythms:
:) Improved understanding
-has helped understanding age-related changes in sleep
-sleep scientists have observed that SWS reduces with age
-growth hormone is mostly produced during SWS, so it is reduced in old people
-Van Cutler et al(2000) suggests that the resulting sleep deficit may explain various issues in old age i.e reduced alertness
-therefore relaxation + meds can be used to increase SWS—} practical value
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Evaluating ultradian rhythms:
:( individual differences
-there is significant variation between people i.e Tucker et al(2007) found large differences between ppts in terms of the duration of each sleep stage(particularly 3 and 4)
-suggests these differences are likely to be biologically determined
-makes it difficult to describe ‘normal sleep’ in any way
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Evaluating ultradian rhythms:
:) High degree of control
-conducting studies of sleep in lab settings control extraneous variables which may affect sleep
-HOWEVER lab studies involve being attached to complicated machinery—} may not represent their ordinary sleep
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Kleitman - the basic rest activity cycle
-a 90 min cycle during sleep which also runs into the day
-BRAC refers to cycle of sleep during the night whereas during the day it refers to the progressive stages of alertness to physiological fatigue that we feel
-research suggests that the human mind can focus for a period of around 90 mins then the body runs out of resources—} leads to loss of conc, fatigue + hunger
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Ericsson et al(2006)
-studied a group of elite violinists + found that among the group, practice sessions were limited to a duration of no more than 90 mins at time
-analysis indicates that the violinists frequently napped to recover from practice(same cycle with artists, writers, chess players etc)
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Endogenous pacemakers
-refers to anything whose origins are within the organism + are the product of inherited genes
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The SCN
-small bundle of nerve cells located in hypothalamus of each hemisphere
-acts as ‘master clock’, with links to other brain regions that control sleep + arousal
-SCN revives info about light from the optic chiasm—} with info about light/darkness, it transmits messages to the pineal gland about secretion of melatonin(even when eyes are closed)
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Animal studies: Decoursey et al(2000)
-destroyed the SCN connections in the brains of 30 chipmunks who were then returned to their natural environment & observed for 30 days
-sleep/wake cycle of the chipmunks disappeared + by the end of the study, a significant proportion of them had been killed by predators(too vulnerable to attacks)
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Animal studies: Ralph et al(1990)
-bred ‘mutant’ hamsters with a 20 hour sleep/wake cycle
-when SCN cells from the foetal tissue of mutant hamsters were transplanted into the brains of normal hamsters
-cycles of 2nd group defaulted to 20 hours
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Evaluating endogenous pacemakers:
:( more than one body clock
-research into SCN may overshadow other body clocks i.e peripheral oscillators—} found in the organs including the lungs, pancreas + skin, influenced by the actions of the SCN but also act independently
-Damiola et al(2000) demonstrated how changing feeding patterns in mice could alter the circadian rhythms of cells in the liver by up to 12 hours whilst leaving the rhythm of the SCN unaffected
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Evaluating endogenous pacemakers:
:( interactionist system
-cannot be studied in isolation—} studies like this are rare i.e Siffre’s study used artificial light which could be classed as an ex zeitgeber
-pacemakers and zeitgebers interact in everyday life—} attempting to isolate them lowers the validity of the research
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Evaluating endogenous pacemakers:
:( ethics
-animal studies i.e chipmunks + hamsters can’t be generalised can’t be generalised to the human brain
-animals in the Decoursey et al study were exposed to risk when returned to natural habitat and most died as a result
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What are exogenous zeitgebers?
external factors in the environment that reset our biological clocks
-in the absence of them, the free-running clock control the sleep/wake cycle
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Light
-key zeitgeber in humans that can reset the SCN and plays a role in the maintenance of the sleep/wake cycle
-has a direct influence of hormone secretion + blood circulation
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Campbell and Murphy(1998)
-demonstrated that light can be detected by skin receptors on the body even when the light is not detected by the eyes
-15 ppts were awoken at various times + had a light shone on the back of their knees
-creates a deviation is sleep/wake cycle sometimes by 3 hours + their temperature and melatonin secretion changing
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Vetter et al(2011)
-demonstrated the importance of light in participation of the sleep/wake cycle + activity test patterns of ppts over 5 weeks
-group that worked under normal ‘warm’ light synchronised their circadian rhythms each day with natural light at dawn
-group who exposed to blue-enriched light didn’t show the same adjustment + synchronised to office hours
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Social cues
-cues like mealtime for babies and social activities have a role as EZ’s and impact the biological rhythm
-Klein + Wegmann(1974)= circadian rhythms of air travellers adjusted more quickly if they went outside more at their destination + adapted to the eating + sleeping habits of locals rather than giving into jet lag
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Evaluating exogenous zeitgebers:
:( environmental differences
-EZ’s don’t have the same effect in all environments
-people who live in the Arctic circle have similar sleep patterns all year round despite spending around 6 months in darkness
-suggests the sleep/wake cycle is primarily controlled by EG’s can override environmental changes in light
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Evaluating exogenous zeitgebers:
:( conflicting case study
-Miles et al(1977) recounts the study of a young man who was blind from birth and had an abnormal circadian rhythm of 24.9 hours
-despite exposure to social cues i.e mealtimes, his sleep/wake cycle couldn’t be adjusted
-suggests that social cues aren’t effective in resetting biological rhythm
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Evaluating exogenous zeitgebers:
:( weak supporting evidence
-findings from Campbell + Murphy have not been replicated
-psychologists have criticised the control of their study + suggested that some light may have been exposed to their eyes
