Biopsychology Flashcards
1
Q
The nervous system made of?
A
- specialised network of cells
- primary communication system
- through electrical signals
- consists of CNS + PNS
(Central + peripheral nervous systems)
2
Q
Functions of nervous system?
A
- Collect, process + respond to info in the environment
- Co-ordinate the working of different organs + cells
3
Q
The Central Nervous System (CNS) ?
A
- Made of brain + spinal cord
- Is the origin of all complex commands + decisions
4
Q
Role of the brain in the CNS?
A
- centre of all conscious awareness
- divided - 2 hemisphere
- covered by cerebral cortex
5
Q
Role of the Spinal Cord in the CNS?
A
- extension of the brain
- passes messages to + from brain
- Connects nerves to the PNS
- responsible for reflex actions
6
Q
The peripheral Nervous System?
(PNS)
What’s PNS further divided into?
A
- transmits messages via millions of neurons to + from CNS
- Divided into Autonomic Nervous System (ANS) + Somatic Nervous System (SNS)
7
Q
- Autonomic Nervous System (ANS) ?
A
- governs vital body functions
- involuntary
EG: breathing, heart rate
8
Q
- Somatic Nervous System (SNS) ?
A
- governs muscle movement
- receives info from sensory receptors
9
Q
2 other nervous systems branching from Autonomic Nervous System (ANS) ?
A
- Parasympathetic Nervous System
- Sympathetic Nervous System
They act in opposition to each other
activity rises in 1 = falls in the other
10
Q
- Parasympathetic Nervous System?
A
- ANS’ normal resting state
- relax the body + return us to our ‘normal’ resting state.
- slows down heart rate + breathing rate
- reduces our blood pressure.
- Functions that were previously slowed down during a fight / flight reaction are started again (e.g. digestion).
11
Q
- Sympathetic Nervous System?
A
- ANS’ state when body’s preparing for a fight or flight situation from a threat or sudden unexpected stimuli
- Impulses travel from sympathetic nervous system to organs to help us prepare for action in dangerous situation
- increased heart rate = more blood to muscles + push adrenaline around body
- Pupils dilate = better vision from more light
- Liver stimulates Glucose release
- less important functions decrease ( digestion, salivation + urination.)
12
Q
Endocrine system?
A
- instructs glands to release hormones into bloodstream carried towards target organs
- communicate via chemicals
13
Q
The endocrine system’s major endocrine glands?
A
- Hypothalamus: regulates body temp, hunger, thirst
- Adrenal gland: secretes adrenaline
- Pituitary gland: controls all other endocrine glands + influences growth
- Thyroid gland: thyroxine + regulates metabolism
- Ovaries: oestrogen released
14
Q
What systems work together in fight or flight situations?
A
Endocrine + ANS (Autonomic Nervous System) work together stressful events of fight or flight
- Sympathetic nervous system in ANS
15
Q
Fight or flight situation?
A
- signals sent to sympathetic branch of ANS
= prepares body for fight/flight (heart rate eg) - sees threat = transmitted via somatic nervous system to brain, amygdala (in brain) sends signals to hypothalamus.
- hypothalamus triggers pituitary gland to send out chemical messages via bloodstream
- Adrenaline released from Adrenal gland
16
Q
What happens after threat has passed?
A
parasympathetic nervous system returns body to resting state
17
Q
What are neurons?
How info flows through neurons?
A
nerve cells that process + transmit messages within them through electrical signals and with other neurons chemically (synapse)
- Dendrites (collect electrical signals) –>
Cell body ( integrates incoming signals + generates outgoing signals to axons) –>
Axon ( passes electric signals to dendrites of another neuron)
18
Q
Sensory neuron?
A
- Carry messages from PNS (Peripheral nervous system) to CNS
- Long dendrites
- Short axons
19
Q
Relay neuron?
A
- connects sensory neuron to motor neuron + other relay neurons
- Short dendrites
- Short axons
20
Q
Motor neuron?
A
- Connects the CNS to effectors (eg muscle + glands)
- Short dendrites
- Long axon
21
Q
Synapse?
Synaptic transmission?
A
Synaptic gap - tiny gap between 2 neurons where neurotransmitters travel across to transfer info.
Synaptic transmission - Process in which neighbouring neurons communicate with each other by sending chemical messages (neurotransmitters) across synapse.
22
Q
Process of synaptic transmission:
A
- Electrical impulse reaches end of presynaptic neuron
- Triggers synaptic vesicles to release neurotransmitters (chemical messengers) that carry signals across synapse
- Bind to the receptors on postsynaptic neuron.
- Converted back to electrical signal and travels through neuron
23
Q
What charge is a neuron in:
- resting state?
- activated by stimulus?
A
- Neuron in resting state : Negatively charged
- Neuron activated by stimulus : positively charged
24
Q
What’s action potential?
A
- When neuron becomes positively charged, causes an action potential to occur - the electrical impulse travels from axon to the end of neuron.
25
Excitatory neurotransmitters / excitation ?
Effect + example
- These excitatory neurotransmitters increase the positive charge of the postsynaptic neuron
= increase likelihood that the postsynaptic neuron will fire + pass on the electrical impulse.
[ EG: Adrenaline ]
26
Inhibitory neurotransmitters / Inhibition ?
Effect + example `
Inhibitory neurotransmitters increase the negative charge of the postsynaptic
= decreases likelihood that the postsynaptic neuron will fire + pass on the electrical impulse.
[ EG: Serotonin ]
27
Studying the brain:
1. fMRI
(Functional Magnetic Resonance Imaging)
- brain-scanning technique that measures blood flow in brain when a person performs a task.
- neurons in the brain that are the most active during a task use the most energy = increased blood flow in those areas to supply more oxygen.
= haemodynamic response
28
Evaluation of fMRI
1. Invasive v non-invasive?
2. Causation?
1. Non-invasive: no radiation or surgery used as person is awake.
- unlike PET scans does not rely on use of radiation = making procedure risk free, non-invasive + straightforward to use.
2. Causation: no direct measure of neural activity. simply measure changes in blood flow = impossible to infer causation (at a neural level)
29
3. Temporal resolution?
4. Spatial resolution?
3. Temporal resolution: Poor (1-4 seconds after activity).
- Psychologists are unable to predict with a high degree of accuracy the onset of brain activity
4. Spatial resolution: good (1-2 mm).
- Psychologists can determine the activity of different brain regions with greater accuracy when using fMRI, compared to EEG / ERP
30
Economic implications?
Expensive compared to other techniques
= reduced sample sizes/ limited number of patients offered an fMRI
= negatively impacts validity of research + is difficult to generalise findings from this technique to a larger population
= may be necessary to use other brain techniques in addition to fMRI which has economical implications for the NHS (there will be an additional cost).
31
Studying the brain:
2. Post-Mortem examination (autopsy)
Brain analysed after death to determine whether certain observed behaviours during lifetime can be linked to structural abnormalities in the brain.
32
Case study: Work of Broca
- Examined the brain of a man who displayed speech problems when he was alive.
- Discovered that he had damage in the area of the brain important for speech production = became known as Broca’s area.
33
Evaluation of Post-Mortem Examination
1. Invasive v non-invasive?
2. Causation?
1. Invasive: brain is cut and person is dead - informed
consent must be given before death (ethical)
Permission is harder to gain = reduced sample size
2. Causation: issues a patient displays during their lifetime (e.g can't speak) may not be linked to the deficits found in the brain.
May be result of another illness = psychologists unable to conclude that the deficit is caused by the damage found in the brain.
34
3. Temporal resolution?
4. Spatial resolution?
3. n/a (no brain activity- minimal neural changes
in the brain after death)
4. n/a (Low, changes seen by the eye, not much detail compared to other methods of investigation)
35
Studying the brain:
3. EEG (Electroencephalogram)
- recording of electrical activity in brain
- signals picked up by electrodes
(useful for diagnosis of epilepsy)
36
The brain waves and how they can be examined?
- Alpha
- Beta (most activity)
- Delta (when asleep)
- Theta
Examine:
Amplitude: the intensity or size of the activity
Frequency: the speed or quantity of activity
37
Evaluation of EEG
1. Invasive v non-invasive
2. Causation
1. Non-invasive: There are no surgical procedures or radiation involved.
2. Causation: No causation. Electrical activity identified in multiple regions = difficult to establish cause + effect.
38
3. Temporal resolution
4. Spatial resolution
3. Temporal resolution: High temporal resolution (1 millisecond) = can accurately detect onset of brain activity quick
4. Spatial resolution: low. Can't pinpoint exact source of neural activity = doesn't allow researchers to distinguish between activities originating in different but adjacent / close locations.
39
EEG Practical application?
- Real practical application + valuable diagnostic tools for epilepsy as it can easily be detected.
-epilepsy: brain's electrical rhythms become imbalanced = causeing seizures as normal electrical pattern is disrupted by sudden bursts of electrical energy
- Has contributed to our understanding of sleep + sleep disorders = led to effective treatment + better quality of life for patients.
40
Studying the brain:
4. ERPs (Event-related potentials)
- Electrodes attached to scalp
- Stimuli presented to ps (eg sound/picture)
- Researchers look for electrical activity related to that stimuli
41
Sensory VS Cognitive ERPs
Sensory ERPs:
- waves occur WITHIN 100 millisecond after stimuli
= reflect sensory response to stimuli
Cognitive ERPs:
- waves occur AFTER 100 milliseconds after stimuli
= demonstrates some information processing
42
Evaluation of ERPs
1. Invasive V non-invasive
2. Causation
1. Non- invasive: no radiation, no instruments directly into brain, no surgical procedure.
2. Causation: Causation can be established
43
3. Temporal resolution
4. Spatial resolution
3. Temporal resolution: excellent temp resolution = more valid measurement of electrical activity when undertaking specific task = can detect origin of brain activity with greater degree of accuracy.
4. Spatial resolution: Poor spatial resolution - unable to provide info on what's happening in deeper regions of brain, just general areas.
44
Economic implications?
cheaper compared to FMRIs = more patients can undertake ERPs + EEG = more widely used for research / diagnosis which can be easily generalised to a larger pop.
45
Localisation of function
- Different areas of brain are responsible for different behaviours/ functions / activities.
- If different areas of brain become damaged (illness/injury) = function associated with that area will be affected.
46
Flourens
- He systematically removed cerebellum of dog's brain = gradually lost ability for regular movement but intellectual faculties not affected but couldn't coordinate movements.
47
Broca :
- Broca studied patient who could only say 'Tan'
- Had difficulty in producing speech
-When he died, Broca performed post-mortem + found Broca's area damaged (language production)
48
Wernicke
= patients had problems understanding language
- had damage in area in temporal lobe
= damage to wernicke's produced difficulty in understanding spoken /written lang + spoke muddled
49
Case study of Gage
damage to brain when rod went through his cheek and out of top of head (frontal lobe)
After = personality altered [more aggressive + abrupt]
= frontal lobe responsible for personality.
50
The 4 main areas of the brain?
- Motor cortex
- Somatosensory cortex
- Visual cortex
- Auditory cortex
51
Motor cortex.
What?
Where?
What?
- controls voluntary movements in opposite side of body.
- Damaged = loss of control over movements
Where?
- The back of the frontal lobe in both hemispheres
52
Somatosensory cortex.
What?
Where?
What?
- sensory info from skin (touch/heat/pressure) is processed
Where?
- front of both hemispheres
53
Visual cortex.
What?
where?
What?
- receives + processes visual information
- Each visual cortex responsible for opposite side eye
- Damage on Left visual cortex damages Right eye + vise versa
Where?
- In occipital lobe at back of brain
54
Auditory cortex.
What?
Where?
What?
- processing sound + analyses speech-based info
- Left side responsible for Right ear
- Damage effects opposite ear = partial hearing loss
Where?
- The temporal lobe
55
AO3 of localisation of functions theory
1. supporting evidence +
2. Functional recovery (opposing evidence)
3. Individual differences -
56
1. Supporting evidence
- supporting evidence from both case studies + brain scans
- Case study of Gage = frontal lobe responsible for personality + emotions as his damaged frontal lobe altered his personality (more aggressive + abrupt)
- Peterson et al's brain scans = broca's area active during reading tasks whilst Wernicke's area active during listening tasks = different areas responsible for different things.
= validates + adds credibilty to theory as provides evidence that diff regions responsible for diff things.
= theory more plausible, furthering our understanding on how different human behaviour are influenced by different brain regions.
57
2. Functional recovery
- Argument against the localisation of function is functional recovery
= When brain becomes damaged + a function is lost = rest of brain takes over responsibility + reorganise itself in attempt to recover lost function
- challenges localisation theory, as while the theory suggest that brain regions each have independent functions functional recvery shows otherwise
- suggesting in order for each area work effectively, they must work with each other as they all interdependent - suggesting brain is more interdependent + interconnected + make LOF theory less credible
= may be more valid to take a holistic approach investigating the relationship between brain + human behaviour as it's evident that this correlation is more complex than suggested by the localisation theory
- Further research needed in order to fully understand how localisation of function works
58
3. Individual differences
- Some psychologists argue that the idea of localisation fails to take into account gender differences
- Herasty found that women have proportionally larger Broca’s + Wernicke’s areas than men, which can explain the greater ease of language use amongst women
- This however suggests a level of beta bias in the theory =
the differences between men + woman are ignored
- variations in the pattern of activation + the size of areas observed during various language activities are not considered
- theory hasn't preduicted that the functions of the different areas in the brain are also affected by the size of these areas, not just the location
= cannot generalise assumptions of localistion of function to evryone as brain structures may differ between men + women
59
Lateralistion Theory
- The 2 halves of the brain are functionally different
- Each hemisphere has different functions
(functional specialisations)
- How much any 1 function is located more in 1 hemisphere than the other one
60
Right hemisphere responsible for?
Left hemisphere responsible for
Right Hemisphere:
- For visual - spatial tasks
- creativity
Left Hemisphere:
- Language + speech
61
Sperry's split-brain research
Aim, IV + DV
Aim: to investigate effects of hemisphere deconnection + show that each hemisphere has different functions
IV - whether ps have split brain or not
(investigated ps that already have existing split-brain due to treatment for epilepsy)
DV - Performance on the different tasks
62
Method / procedure
3 conditions/tasks:
1. Describe what you see
2. Tactile test (touch)
3. Drawing test
63
Findings for
1. Describe what you see
- Pic presented to R visual field
(processed by L hemisphere)
= ps could describe what they saw = shows L hemisphere = language
- Pic presented to L visual field
(processed by R hemisphere)
= ps could NOT describe what they saw = often said "nothing there"
64
Findings for
2. Tactile test (touch)
- Object placed in R hand
(processed by L hemisphere)
= can describe verbally what they felt + select similar feeling object with R hand
- Object placed in L hand
(processed by R hemisphere)
= CAN'T describe verbally + CAN select similar feeling object with L hand
65
Findings for
3. Drawing test
1. Picture presented to R visual field
(processed by L hemisphere)
= R hand would attempt drawing but L hand drawing much clearer than R hand = R hemisphere for visual motor tasks
2. Picture presented to L visual fields
(processed by R hemisphere)
= L hand consistently better drawing than R even though they R handed
= demonstrates superiority of R hemisphere for visual motor tasks
66
Evaluation of Lateralisation theory
- Supporting evidence (Sperry et al + Wada's test)
- Methodological issues with supporting evidence
- Individual differences
67
1. supporting evidence
(Sperry et al + Wada's test)
-Supporting evidence from Sperry et al + Wada's test that show differences in L + R hemisphere.
-Sperry et al found that different hemispheres of brain specialise in different tasks.
-EG the L hemisphere responsible for language whilst the R for visual special tasks + creativity.
-Wada’s test also showed how when the left hemisphere was numbed with anaesthetics the PS couldn't count anymore = L hemisphere is responsible for language.
-when the R hemisphere was numb = PS couldn't count with finger movement = responsible for visual-spatial tasks.
- findings add credibility + validity to lateralistion theory making it more plausible + reliable
= increases understanding on how different hemispheres specialise differently.
68
2. Methodological issues w supporting evidence
- Limitation of supporting evidence from Sperry's split-brain research is there's methodological issues.
- Sperry used a quasi experiment as his 11 ps already had split-brain before.
- As IV (split brain) cannot be manipulated = researcher cannot have full control over situation = harder to establish cause + effect between IV + DV
- Small sample size (11) = unrepresentative + can't generalise to everyone.
- used repeated measure design = order effect = demand characteristics = reduce internal validity
- Despite limitations, its most approproate + needed as it would be unethical to give ppl split brain procedures for study = used ps that already have split brain due to epilepsy treatment
69
3. Individual differernces
- Limitation is that it takes nomothetic approach + ignores individual differences.
- As Sperry used small sample size of 11 = less likely that there was much individual differences = findings established unlikely to apply to all people, as due to individual differences ppl's hemispheres may functioning slightly different ways than this theory suggests, EG biological differences in brain size (men - larger brains)
- This is a weakness as it limits the usefulness of the research as Sperry can't generalise the findings of lateralisation of function to all people not just those who have had the split brain operation due to severe epilepsy
- Lower external validity .
- For more valid and representative theory, a ideographic approach should be taken with a larger sample size.
70
Brain plasticity / cortical remapping
- The brain's ability to change + adapt as a result of experience
- Important for development + behaviour
71
When does brain experience most growth in number of synaptic connections?
The older you get..the..?
- 1st 5 years - brain experiences most growth in number of synaptic connections made
- 2-3 yrs = 15,000 connections made (2x as adult)
- Older u get = brains ability to change falls + effort it takes to change increases
72
Evidence ( supporting evidence )
1. Maguire et al
2. Mechelli et al
73
1. Maguire et al
- Studied brains of taxi drivers
= hippocampus volume larger than control group = as its responsible for development of spatial + navigational skills
- as taxi drivers are required to learn lots of navigation
= areas of brain responsible (hippocampus) get larger = structural plasticity
74
2. Mechelli et al
- Bilingual brains have larger left inferior parietal cortex than monolingual brains
= This part of brain = responsible for language
75
AO3 for brain plasticity?
1. Supporting evidence
2. Methodological strength of supporting evidence
3. Practical application
76
1. Supporting evidence
1. Supporting evidence from Maguire et al + Mechelli et al show proof of how brain changes and adapts as a result of experience to help improve behaviour
- Validates + adds credibility to brain plasticity theory, making it more reliable + furthering our understanding on some reason why our brains change
.
- However, evidence has also shown that the older you get the less able your brain is to change + the more effort it takes.
- This can explain why surviving strokes is much more common in children than adults, as they are able to undergo rehabilition and brain can adapt and change to help them recover
- This makes BP theory limited as cannot be generalsied to whole population, but is mostly relevant to younger population.
77
2. Methodological
2. Methodological strength of supporting evidence
- very scientific as they use brain scans
- Have features of science such as being replicable and objective
= findings have high internal validity
= can establish cause + effect
= adds credibility + makes theory more reliable
- However cannot 100% say that the larger volume in hippocampus of drivers is due to taxi driving
- other factors may have impacted this
= lower internal validity + our confidence in the brain plasticity theory
78
3. Practical application
- Understanding the process involved in brain plasticity has contributed to the field of neurorehabilitation
- Patients who have had an injury affecting the brain can have a slow + long recovery, Neurorehabilitation may be used to maintain improvements in functioning, including electrical stimulation therapy
- Uses motor therapy + electrical stimulation of the brain to help brain change and recover itself after an incident to regain some of the damaged/lost function
- This demonstrates the positive application of research in this area to help improve the cognitive functions of people suffering from injuries, give them a higher chance of recovery + ultimately improving their quality of life
79
Functional recovery
- Brain functions move from damaged areas to undamaged areas through rewiring + reorganizing to form new synaptic connections close to areas of damage.
- Secondary neural pathway that would not typically be used for certain function are rewired + reorganized so they can be activated + enable new function.
80
Supporting evidence
Tajiri et al
- stem cells provided to rats after brain trauma showed clear development of neuron like cells in areas of injury
= shows ability of the brain to create new connections using neurons made by stem cells
81
Evaluation points of Functional recovery
1. Supporting evidence from Tajiri et al + stroke patients
2. Methodological - of animal study used in Taijiri
3. Individual differences ( Elbert et al)
82
1. Supporting evidence ( Taijiri et al + stroke patients)
- Tajiri et al: stem cells provided to rats after brain trauma showed clear development of neuron like cells in areas of injury
= shows ability of the brain to create new connections using neurons made by stem cells
- Case studies of stroke victims who have experienced brain damage + have lost some brain functions have shown that the brain has an ability to re-wire itself with undamaged brain sites taking over the functions of damaged sites.
- This adds validity + credibility to the functional recovery theory as stroke patient's brains show that neurons next to damaged brain sites can take over some of the functions that've been lost.
83
Methodological issues
- Methodological issues with using animal studies for studying functional recovery in humans.
- Although the findings have furthered our understanding on how brain forms new neurons in damaged areas through rewiring + reorganising, there are issues with using animal studies
= We cannot fully extrapolate the findings to humans as our brains are much more complex than rats and hence neuron processes may occur slightly different in them compared to rats brains
= For more valid findings that are more representative of humans, further research may be needed on human minds instead.
84
3. Individual differences
-Individual differences may be important in functional recovery = not considered, as it's a nomothetic approach
-Elbert et al concluded that neural regeneration is less effective in older brains.
=may explain why recovery after strokes is higher in kids than adults.
- Other studies (Schneider et al) found that patients with a college education were ×7 times more likely recover from their disability after 1 year than those without education.
= more active, neurologically well-connected brain = higher speed of recovery from traumatic brain injuries.
= it's important to take a more idiographic approach + consider individual differences when investigating functional recovery as it is less likely to be scientifically misleading as these factors (age + education level) can impact it
85
What are Biological rhythms?
Patterns of change in body activity due to cyclical time periods.
Affected by Endogenous pacemakers + Exogenous zeitgebers.
86
Biological rhythms
1. Circadian rhythms?
2. Ultradian rhythms?
3. Infradian rhythms?
1. Circadian rhythms: Last 24 hrs
(sleep/wake cycle)
2. Ultradian rhythms: last less than 24 hrs
3. Infradian rhythms: last longer than 24 hrs
87
Endogenous pacemakers?
Exogenous Zeitgebers?
Endogenous pacemakers: Body's INTERNAL biological clock that regulates many biological rhythms (melatonin release)
Exogenous Zeitgebers: EXTERNAL cues that may affect our biological rhythm (light on sleep/wake cycle)
88
Supporting evidences?
1. Michel Siffre case study
2. Aschoff + Wever
89
1. Siffre case study
- Siffre spent long period in cave without natural light, sound (had food/water + artificial lamp)
-Came out on mid Sep, but thought it was still mid August
90
Findings + conclusions
- His biological rhythms became around 25 hrs (just slightly over 24 hrs)
- He continued to sleep + wake on regular schedule (Endogenous pacemakers)
= continues of circadian rhythms show endogenous clock but clock wasn't completely accurate (25) + varied daily = external cues important.
91
Evaluation AO3 of Siffre
**+**
- provides evidence for existence + influence of **endogenous pacemakers** as despite being in dark cave away from sunlight, circadian rhythm continued
**-**
- **Methodological** limitation of case study = can't generalize + apply findings to whole population.
- **Individual differences** need to be considered, Siffre was 60 yrs, so way his body functions may differ from younger ppl
- **beta gender bias** - use male participant only = findings only tells us about the EP + EZ control of male circadian rhythms. Females are physiologically different to males so may differ slightly
=more **Idiographic approach** should be taken
92
Aschoff + Wever
- group of ps spent 4 weeks in a WW2 bunker deprived of natural light
93
Findings + conclusion
- All but 1 ps (29 hrs) had circadian rhythm between 24-25 hrs after
- most participants soon settled into a sleep/wake cycle of between 24 and 25 hours, although some rhythms were as long as 29 hours
= Suggests the 24 hr sleep/wake cycle is impacted heavily by exogenous Zeitgebers (eg N of hrs of sunlight pr day)
94
Evaluation AO3 of Aschoff + Wever
**+**
- provides support for influence of **exogenous zeitgebers** as suggests the natural circadian rhythm is slightly shortened by the effects of daylight (an exogeneous zetgeber)
**-**
- **Individual differences** should be considered - can't generalize to all
- the evidence is based on only a few individuals = low population validity = difficult to generalise finings to whole population
- **Beta gender bias** - use male participant only = findings only tells us about the EP + EZ control of male circadian rhythms.
Females are physiologically different to males so may differ slightly
- it takes a nomothetic approach,**ideographic** should be taken instead
95
Practical application of circadian biological rhythm
1. consequences of desynchronisation
2. To pharmacokinetics
3. Hormones
96
Practical application:
consequences of desynchronisation
- Knowledge of circadian rhythms has given researchers a better understanding of the adverse consequences of desynchronization + distruption to biological rhythms
- EG night workers engaged in shift work experience a period of reduced concentration around 6:00 am meaning accidents are more likely - high melatonin at night = sleepy
- sleep during day instead = light (EZ) = poor sleep = more tired at night
- shift workers are 3x more likely to develop heart diseases
- famous accident where gallons of oil spilled into sea at midnight due to low concentration at that time
- consequently research into the sleep/wake cycle may have economic implications in terms of how best to manage shift patterns of night workers so that they are more productive and make fewer mistakes
97
Practical application:
To pharmacokinetics
- Research into the circadian rhythm has furthered our understanding into pharmacokinetics- the action of drugs on the body + how well they are absorbed and distributed
- chronotherapeutics - importance of the specific time patients take medication, as this can have a significant impact on treatment success.
- EG flu jabs are more effective in the morning.
- additionally as the risk of heart attack is greater earlier in the morning drug treatment is administered before the patient goes to sleep however the drug is not released until the vulnerable time of 6 am to reduce the risk
98
Practical application:
Hormones
- Hormones like melatonin + cortisol may rise/fall as part of your circadian rhythm.
- melatonin hormone = makes you sleepy + your body releases it more at night time + suppresses it during the day according to light in your surroundings.
- cortisol increases alertness so it's increased more during the day and less at night when its dark.
99
Individual differences
Duffy et al found that morning people prefer to rise + go to bed early (6:00 am - 10 pm) whereas evening people prefer to wake + go to bed later (10 am - 1am). Czeiser et al Found out circadian Cycles can vary from 13 - 65 hours.
=Individual differences need to be considered as they can impact sleep=wake cycles - this law cannot be generalised to everyone.
100
Supporting evidence for Biological rhythms
-Evidence to support the influence of exogenous zeitgebers.
-Siffre investigated free-running circadian rhythms = found that the absence external cues significantly altered his sleep wake cycle to just beyond 24 hours (25 hours).
-Aschoff + Wever (1976) found that all but 1 of the Ps who were deprived of natural light displayed a circadian rhythm between
24-25 hours.
-This supporting research suggests that the natural sleep/wake cycle might be longer than 24 hours but that is affected by exogenous zeitgebers such as light + meal times.
-This furthers our understanding into effects of exogeneous zeitgebers on biological rhythms.
101
Biological rhythms: Infradian rhythms
EG?
= Biological rhythms which last more than 24 hrs.
- Menstrual cycle ≈ 28 days
- Seasonal affective disorder (yrly cycle)
102
Evidence for infradian rhythms:
McClintock (1998)
method:
- 29 women with history of irregular periods
- samples of pheromones gathered from 9 women in different stages of cycle
(via cotton pad in armpit)
- Pads treated with alcohol + frozen + rubbed on upper lip of other 20 ps
103
Findings + conclusions?
- found 68% women experienced changes to their cycle which brought them closer to cycle of their 'odour doner'.
= Women's cycles can be synched by exposure to pheromones (odour) of other women on period = exogeneous zeitgebers
104
Evaluation:
adaptive response
-There's evidence that the McClintock effect, menstrual synchrony, may be an adaptive response.
-Menstruating together = women fall pregnant around same time = new-born's can be cared for collectively increasing chances of offspring's survival.
= suggests that women's reproductive behaviour is motivated by their infradian rhythms = highlighting importance of studying infradian rhythms in reproductive behaviour.
105
Evaluation:
methodological
-There are methodological limitations with research into the synchronisation of menstrual cycles.
-Some argued that the research fails to acknowledge that many factors affect the change in woman's cycle including stress, diet, exercise
= which can act as confounding variables.
=For this reason it is difficult to establish causation between the synchronisation of menstrual cycles + exogenous zeitgebers such as pheromones; any patterns of synchronisation could have happened by chance.
= This can explain why other studies have all failed to replicate findings = low reliability.
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Infradian rhythms:
Seasonal Affective Disorder
A depressive disorder which has seasonal pattern of onset, triggered during winter months when daylight hrs reduce = low mood, general lack of activity + interest in life.
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Explanation?
Due to hormone melatonin
During the night = more melatonin secreted by pineal gland until dawn
In winter, lack of light = melatonin production increases for longer = has a knock on effect on levels of serotonin in brain = which is linked to depressive symptoms
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Treatment
(light box)
A box which stimulates very strong light to reset bodies internal clock = helps reduce effects of SAD, in ≈ 80% of people (study: Sanassi)
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Evaluation points of seasonal affective disorder:
1. Supporting evidence
2. Led to effective treatment (light box)
3. Placebo effect
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1. Supporting evidence
-Terman (1988) found that rate of SAD is more common in Northern countries where winter nights are longer..
-He found SAD affects around 10% of people living in New Hampshire (a northern part of the US) but only 2% of residents in southern Florida.
-These results suggest that SAD is affected by light (exogeneous zeitgeber) that results in levels of melatonin.
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2. led to effective treatment
Phototherapy is the use of a lightbox to simulate light in the morning to reset melatonin levels in people with SAD.
Eastman et al 1998, found that this relieves symptoms in up to 60% of sufferers = effective treatment
- However can cause headaches + eye strain
- Effects wear off over time = relapse rate is 46% compared to CBT relapse rate of 27%
- effective short term treatment but additional treatment may be required
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Placebo effect limitation
-Eastman et al recorded a placebo effect with the the lightbox treatment.
-30% of the patience got better without the lightbox, but they thought that they were getting the light (placebo).
= If they go better without the use of light this questions the validity of the causation of SAD, as if it is caused by light, then treatment without light would be hard to achieve, yet Eastman found 30% did.
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Biological rhythms: ultradian rhythms
EG:
Last less than 24 hrs
Sleep cycle - 90 minutes
( NOT sleep/wake cycle. DO NOT CONFUSE!!!)
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Sleep cycle
- Cycle alternates between REM (rapid eye movement) + NREM (non-rapid movement) sleep + consists of five stages.
- The cycle starts at light sleep, progressing to deep sleep + then REM sleep, where brain waves speed up and dreaming occurs.
- This repeats itself about every 90 minutes throughout the night.
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Different stages of the sleep cycle?
**Stage 1+2**: 'light sleep', brain patterns becomes slower. Starts with ALPHA waves + progresses to THETA waves
[Non-REM sleep]
**Stages 3+4**: 'deep sleep', slow wave sleep stage + associated with DELTA waves [Non-REM sleep]
**Stage 5**: REM sleep (rapid eye movement) = dream sleep Body = paralysed. Brain = similar to awake person. THETA waves.
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1. Supporting evidence of the sleep cycle
Dement + Kleitman
- Monitored sleep pattern of 9 ps in sleep lab
- brainwave activity recorded on an EEG
(caffeine + alcohol controlled)
= REM activity during sleep highly correlated with how vivid dreams were + ps recalled very accurate recall of dreams
= REM sleep very important component of the ultradian sleep cycle
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2. Methodological:
- There are methodological strengths + limitations of Using EEGs and sleep labs to investigate untradian rhythms.
- Strength = sleep labs highly controlled + standardised procedure = cause + effect can be established + extraneous variables reduced (coffee) = high internal validity findings.
- Using scientific EEGs = provides accurate scientific + precise information on different waves involved throughout sleep cycle.
- However, methodological issues of sleep lab = different environment + more artificial than ps' bedrooms + electrons attached on heads.
=These factors can lead to participant sleeping in a way that does not represent their ordinary sleep patterns = findings lower external validity
- However, despite this, sIeep is a natural phenomena, it's unlikely that the findings will vary too much in a more natural setting.
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3. Individual differences
- It's important to consider role of individual differences when investigation sleep cycles as a example of Ultradian rhythm.
- Tucker et al found significant differences between participants in terms of the duration of each stage (particularly stages 3 + 4)
- This demonstrates that there may be innate individual differences in Ultradian rhythms, which means that it is worth focusing on these differences during investigations into sleep cycles.
- For a better understanding into steep cycles it 's important to take a more idiographic approach as research into sleep cycles can differ between people
