BIOPSYCHOLOGY Flashcards
the nervous system
specialised network of cells in the body, made up of the brain, spinal cord and nerves
body’s communication system that controls much of what your body does
function to collect, process and respond to information in the environment and to coordinate the working of different organs and cells
the nervous system list of functions
brain growth and development
sensations
perception
thought and emotions
learning and memory
movement, balance and coordination
sleep
nervous system regions
nervous system –> central –> brain + spinal cord
nervous system –> peripheral –> somatic + autonomic –> sympathetic + parasympathetic
central nervous system
BRAIN - collects info from sensory receptors and relays this to the muscles and glands of the body through the spinal cord
SPINAL CORD - carries signals to and from the brain + governs reflex actions that do not need to be processes by the brain
frontal lobe
responsible for consciousness and communication, memory and attention, motor control, problem solving and speech production
parietal lobe
responsible for sensory perception
occipital lobe
responsible for visual processing
temporal lobe
responsible for auditory processing, language comprehension and memory retrieval
brain stem
lower part of the brain, connected to spinal cord, responsible for regulating most of the body’s automatic functions and involuntary responses
cerebellum
involved in coordinating movement and balance, plays a role in cognitive functions like language and attention
brain structure
F P
T O
BS C
peripheral nervous system
contains all nerves outside the CNS and relays messages (nerve impulses) to and from the CNS
made up of somatic and autonomic nervous system
somatic nervous system
facilitates communication between the CNS and the environment or senses
mostly under conscious control and controls skeletal muscles
made up of sensory neurones that carry information to the spinal cord and brain and motor neurones that allow the brain to control movememnt
role is to carry sensory information from the environment to the brain and provide muscle responses via the motor pathways
autonomic nervous system
regulates involuntary physiological processes without conscious control
influences activity of most tissues and organ systems as it controls smooth muscles, internal organs and glands
important role in homoeostasis
only consists of motor pathways
made up of sympathetic and parasympathetic nervous systems - antagonistic (one active while the other relaxes)
sympathetic nervous system
typically involved in responses that prepare the body for fight or flight - adrenaline
impulses travel from the sympathetic nervous system to organs to help prepare for action when in a dangerous situation
e.g. increase heart rate, blood pressure and breathing rate
less important functions e.g. digestion, salivation, need to urinate are suppressed
parasympathetic nervous system
role is to relax the body and return us to normal resting state after fight or flight response
slows down heart and breathing rate, reduces blood pressure
‘rest and digest’ system
functions slowed down are started again e.g. digestion
cell body
contains nucleus and mitochondria
(DNA and provides energy)
dendrites
branches on cell body of each neurone that receives information from neighbouring neurones to trigger action potential
axon hillock
where nerve impulse is triggered from
axon
a tube-like structure
carries impulse away from cell body down the length of the neurone
myelin sheath
layers of fatty deposits that provide insulation for protection and help speed up the rate of message transmission
axon terminal
end of the axon
separated from other neurones by synapse
neurotransmitters
chemical messengers released from vesicles in terminal buttons and travel across the synapse and pass on the signal to the dendrites on the post-synaptic neurone
each has individual molecular structure with specific receptor sites that bind to dendrites of post-synaptic neurone
some are excitatory - cause increase in impulses
some are inhibitory - slow impulses
node of ranvier
gaps in the myelin sheath that force the impulse to ‘jump’ across the gaps along the axon, to help speed up the impulse
sensory neurones
transmit nerve impulses
found in receptors e.g. eyes, ears, tongue, skin
carry nerve impulses from the PNS to the CNS (muscles –> spinal cord / brain)
when nerve impulses reach the brain they are translated into ‘sensations’ e.g. vision, hearing, taste, touch
not all sensory neurones reach the brain - some stop at the spinal cord, allowing for quick reflex actions
unipolar - transmit messages in one direction
long dendrites, short axons, cell body coming off axon
relay neurones
found connecting sensory and motor neurones - allowing them to communicate
in brain, visual system and spinal cord
send and recieve messages within CNS
short dendrites and axons
have no myelin sheath - protected by spinal cord, short enough that do not need to be sped up
motor neurones
found in CNS but axons lie outside of CNS
control muscle movement and gland activity (effectors)
release neurotransmitters that bind to receptors on muscles to trigger a response when stimulated
leads to movement
short dendrites and long axons
reflex arcs
reflex actions terminate in the spinal cord to allow for a quicker response
receptors in the skin sense heat and nerve impulse transmits a message to the CNS via the PNS
relay neurones in the CNS carry the message to motor neurones
motor neurones send messages to the effectors creating a physical response e.g. moving away
action potential
change in electrical charge of a neurone that causes it to fire or not
messages sent through neurones electrically but passed across synapses chemically
when neurone is inactive
negatively charged
resting potential –> sodium and potassium ions are in lower amounts inside than outside the neurone
when neurone is stimulated
becomes positively charged
sodium ions move through cell membrane into neurone
generates an action potential which creates an electrical impulse that travels down the axon towards the end of the neurone
once action potential has reached its peak
channels allowing the flow of sodium close and the potassium ones open
positively charged potassium moves out of the neurone, making it return to its negative resting state - depolarisation
noradrenaline
excitatory
stress hormone produced within adrenal gland
quickens hormone, increases stroke volume, opens bronchioles etc.
part of fight or flight response to fear, panic or percieved threat
dopamine
excitatory
related to learning, emotions, cognitive functioning, movement control
enables us to see and take actions towards rewards
contributes to feelings of pleasure and satisfaction as part of reward system - plays role in addiction
serotonin
inhibitory
key role in maintaining mood balance
low levels linked to depression
role in appetite, emotions, motor, cognitive and autonomic functions
not known if has direct affects or overall role in coordinating nervous system
synaptic transmission
process of transmitting messages in the form of neurotransmission from neurone to neurone
cell’s electrical impulse / action potential is generated at the axon hillock, but once the impulse reaches the terminal buttons, it turns into a chemical message which cross the synaptic gap to the post-synaptic neurone
each neurone produces a certain neurotransmitter and when action potential reaches the terminal buttons, vesicles containing the neurotransmitter travel towards the membrane of the pre-synaptic neurone, which the casing of the vesicles fuse with, releasing the neurotransmitter into the synapse
neurotransmitters move from high to low concentration - pre- synaptic neurone –> post-synaptic neurone
neurotransmitter then picked up by receptors on post-synaptic neurone and binds to specific receptors –> receptor site activated
stimulation of post-synaptic neurone results in () of post-synaptic neurone
excitation (depolarisation) - electrical charge becomes more positive
inhibition (hyperpolarisation) - electrical charge becomes more negative
ion channels on post-synaptic membrane open to allow ions to flow in and out
neurotransmitters are either broken down by enzymes or reabsorbed by the pre-synaptic neurone (reuptake)
synapse
specialised gap between neurones, through which the electrical impulse from within the neurone is then transmitted chemically via neurotransmitters
summation
addition of excitatory and inhibitory influences on post-synaptic neurone
can recieve both positive/excitatory and negative/inhibitory
potentials are summed and net effect determines whether neurone fires or not
if ions flow in and trigger an action potential = excitation
if ions flow in but do not trigger an action potential = inhibition
endocrine system
regulates cell or organ activity and controls vital physiological processes
works alongside the nervous system
made up of network of glands across the body that secrete chemical messages called hormones that bind with specific receptors to regulate activity
information transmitted via blood vessels
each hormone produces different effects (behaviours)
each gland produces a different hormone - excite/stimulate a particular part of the body
gland
organ that makes one or more substances, and releases them into the bloodstream or into an opening to the inside or the outside of the body
hormone
chemical substances that act like messenger molecules
travel to other cells and organs and help to control how they work
through bloodstream
comparison of nervous and endocrine systems
NS works faster - neurones are interconnected but functions are more specific and short lived
ES is slower - signal transmission slower through bloodstream but acts more generally and lasts longer
hypothalamus
releases corticotropin-releasing hormone
connected to pituitary gland and is responsible for stimulating / controlling release of hormones from pituitary gland
control system which controls, regulates and drives the endocrine system
pituitary gland
anterior lobe secretes adrenocortical trophic hormone (ACTH) –> stimulates the adrenal cortex and release of cortisol during stress response
posterior lobe secretes oxytocin –> responsible for uterus contractions during childbirth
known as master gland as hormones released stimulate release of other hormones from other glands
receives signals from hypothalamus
pineal gland
releases melatonin –> responsible for important biological rhythms e.g. sleep-wake cycle
thyroid gland
releases thyroxine, responsible for regulating metabolism
adrenal gland
releases adrenaline and noradrenaline from adrenal medulla –> role in fight or flight
releases cortisol from the adrenal cortex, which stimulates the release of glucose to provide the body with energy while suppressing the immune system
ovaries
releases oestrogen –> controls regulation of female reproductive system, including the menstrual cycle and pregnancy
testes
releases androgens, including testosterone which is responsible for the development of male sex characteristics during puberty and muscle growth
fight or flight process
amygdala
hypothalamus
sympathetic nervous system
adrenal medulla
adrenaline + noradrenaline
fight or flight response
fight or flight response description
amygdala activated when someone enters a potentially stressful situation (responds to sensory input and connects it with emotions associated to the fight or flight response e.g. fear, anger)
if situation is deemed stressful/dangerous, a stress signal is sent to the hypothalamus
hypothalamus releases hormones to activate the sympathetic nervous system
if short-term response required, sympathomedullary pathway is activated
sympathetic nervous system triggers adrenal medulla which secretes adrenaline and noradrenaline into the bloodstream
causes physiological changes preparing the body for fight or flight
physiological changes for fight or flight
increased heart rate, blood flow and blood pressure
–> increase amount of blood supplied to the brain and skeletal muscles to enhance ability to fight or flee
increased breathing rate
–> increase oxygen intake
muscle tension
–> prepare for action, improve reaction time and speed
pupils dilate
–> vision becomes acute to focus attention on danger
sweating
–> temperature regulation
–> keep cool and maintain efficiency of the body so more likely to survive a dangerous event
diversion of blood away from skin and digestive system
–> lead to feelings of nausea or ‘butterflies’
–> to save energy to prioritise functions such as running
–> blood forced to major muscle groups
relaxation of bladder
–> reduction of non-essential functions to increase energy for essential functions
after fight or flight
once threat has passed
parasympathetic nervous system activated to return the body to its normal resting state
heart rate, blood pressure and breathing rate reduced
any functions previously slowed are started again
fight or flight weaknesses
human behaviour is not limited to just two responses
Gray also a freeze response, where we appraise situation to decide next course of action
- first response to avoid confrontation altogether
- weigh up options but can result in danger from slower action
behaviour not limited to fight and flight
beta bias may exist –> refers to theories that ignore or minimise sex differences + assume that male study results apply equally to females
Taylor found that females adopt a ‘tend and befriend’ response in dangerous situations - are more likely to try and protect offspring and form alliances rather than fight or flee (are physically weaker so running or fighting may be unsuccessful)
can be argued that fight or flight is a typically male response
early research conducted on men, so researchers assumed findings could be generalised to women
fight or flight response may not be adaptive in modern day
response would have been a useful survival mechanism for ancestors who faced physically life-threatening situations (predators), but modern life rarely requires such an intense biological response
stressors of modern day life can repeatedly activate the fight or flight response, which can have a negative consequence on health
stress
body’s biological response to an actual or percieved stressor
in evolutionary past, would have been essential to survival as enables the body to respond quickly to danger
today there is less danger in our environment but is still needed
sometimes responds to pressures and events not designed for and can lead to physiological and physical illness
acute stress response
SAM pathway
responds quickly to immediate danger and readies the body for fight or flight response
chronic stress response
hypothalamic-pituitary-adrenal pathway/axis (HPA)
responds to long-term constant stressors by keeping body alert
can also have harmful effects on body e.g. reducing immune system functioning
activated by hypothalamus when initial surge of adrenaline subsides
localisation of function
different areas of brain perform different functions for different parts of the body
holistic theory
prior to Broca and Wernicke
all parts of the brain are involved in all functions
contralaterally
each hemisphere controls and processes info from the opposite side of the body
cerebral cortex
outer layer, involved in higher cognitive functions
frontal lobe
personality characteristics, decision making and voluntary movement
parietal lobe
stimulus perception
touch, pressure, temperature and pain
temporal lobe
auditory processing, memory and language comprehensions
occipital lobe
visual info
motor cortex
back of frontal lobe on both hemispheres
voluntary movement on opposite side of the body
damage results in loss of control over fine movements
somatosensory cortex
front of both parietal lobes
sensory info represented
size of area corresponds to sensitivity
visual cortex
posterior of occipital lobe
each eye sends info from RVF to LVC and vice versa
damage to left can produce blindness in RVF of both eyes
auditory cortex
temporal lobes
analyses speech based info
damage may produce hearing loss
language processing in which hemisphere?
left
Broca’s area
left frontal lobe
responsible for speech production
damage causes Broca’s aphasia (non-fluent) - slow, laborious, lacks fluency
Wernicke’s area
left temporal love
speech comprehension
can produce language but cannot understand - fluent but meaningless
Wernicke’s aphasia (fluent) - production of nonsense words
localisation of function strengths
case study evidence
Phineas Gage - only personality affected, holistic theory suggests multiple functions would have been damaged
valid concept, cautious with case studies
HOWEVER, is a case study, cannot be replicated or generalised
localisation of function strengths
supporting, scientific evidence
Raine’s brain scanning of murderers, had less activity in prefrontal lobe and abnormal activity in amygdalae than controls.
empirical, falsifiable, objective
reliable, valid
HOWERVER, only provides a neural correlate, cannot explain why
localisation of function weaknesses
some functions involve multiple areas
voluntary movement localised to motor cortex, tactile sensory processing in somatosensory cortex
language comprehension and production uses both Broca’s and Wernicke’s - more complex, uses more areas, require interaction
localisation depends upon complexity of task
localisation of function weaknesses
individual differences
Herasty found that women have larger B and W’s area - greater ease of language
beta bias - differences in brain structure and function are ignored
some individuals have language processing in homologous areas in right hemisphere
can vary in size and location
localisation of function weaknesses
equipotentiality theory
brain damage, can reorganise itself, intact areas take over lost functions
theory suggests that function would be lost if localised
brain can demonstrate plasticity to relocate if necessary
visual motor tasks in which hemisphere?
right
hemispheric lateralisation
two hemispheres are functionally different and have different functional specialisations
corpus callosum
white matter, thick bundle of fibres connecting two hemispheres
enables interhemispheric communication
visual processing
both contralateral and ipsilateral (on same side)
info processed depending on which field it comes from
both eyes take in info from right and left visual fields
object in RVF
seen by both eyes
processed in left visual cortex
object in LVF
seen by both eyes
processed in right visual cortex
if you want to say what you have seen
object from LVF process by RVC, info passed through corpus callosum to left hemisphere
if you have a severed corpus callosum
in LVF, processed in RVC, but cannot say what you have seen as info cannot be passed to language processing area in left hemisphere
in RVF, can say as processed in left hemisphere
split brain research
commissurotomy, severs corpus callosum
alleviates epilepsy
two hemispheres do not exchange info
Sperry and Gazzaniga aims
examine extent to which two hemispheres are specialised for certain functions
Sperry and Gazzaniga method
sample of people who had a commissurotomy, control of people with CC intact
lab, quasi experiment
image or word projected to LVF or RVF
verbal, drawing and tactile task
verbal task
picture presented, had to describe what they saw
RVF: could describe (language production in LH)
LVF: could not describe, reported that there was nothing present
drawing task
presented with picture and had to draw what they saw
RVF: right hand would attempt to draw a picture, not as clear as left, as right hemisphere superior for visual motor tasks
LVF: left hand would draw clearer and better pictures (even though all right-handed)
tactile task
object placed in hand, had to describe what they felt or select a similar object
object in right hand: verbally describe, select appropriate object
object in left hand: could not describe, select appropriate object
Sperry and Gazzaniga conclusion
language centres in left hemisphere
right hemisphere dominant for visual-motor tasks
further split-brain research
faces projected to both VF
faces in LVF were recognised bit not in RVF
suggests facial recognition occurs in right hemisphere
hemispheric lateralisation strengths
scientific research
quasi experiment (no random allocation)
lab, standardised procedure
easy to replicate for consistency
used same procedure multiple times with similar findings, reliable and consistent findings, credible
HOWEVER, lack of controls
control group with normal CC
not valid as ppts originally suffered from epilepsy, may affect brain operation
differences not as a result of severed CC
hemispheric lateralisation weaknesses
low generalisability and pop. validity
ppts who had severed corpus callosum as treatment for epilepsy
may affect function of brain, sample not generalisable or representative
hemispheric lateralisation weaknesses
evidence to refute
Kim Peek born w/o a CC
could read extremely quickly and remember everything. scanned left page with left eye while reading right page with right eye
language normally processed in left temporal lobe, contralateral transfer
could process in each hemisphere independently, language centres in both
functions can develop bilaterally from birth if brain still developing
neuroplasticity
brain’s ability to change and adapt in structure and function, creating new neural pathways and getting rid of old ones in response to experience and learning
makes new neurone pathways, making larger systematic adjustments - cortical remapping
occurs in all healthy people, especially children, and in people who suffered a brain injury
plasticity during development
synaptic pruning
rarely used connections and deleted and frequently used connections are strengthened
early childhood –> 20s, peaks in adolescence
plasticity through learning
brain changes when something new is learned, change in internal structure of neurones and synapses, increases number of synapses
plasticity as we age
originally thought restricted to childhood, occurs throughout lifetime, although easier in childhood and declines with age
Maguire et al procedure
MRIs of 16 right-handed male London tax drivers for more than 1.5 years
scans of 50 right-handed males as comparison, same mean age
comparison against control group and quasi correlation between experience and hippocampus activity and size
Maguire et al findings
increased grey matter in brains of taxi drivers in right and left hippocampi compared to control
increased volume in posterior hippocampus, associated with spatial awareness and navigation
longer in job, the more pronounced structural difference, structure adapted
brain adapts and responds to acquiring new skills and knowledge
Maguire et al evaluation
low pop. validity
- small sample (16)
- androcentric (male)
- ethnocentric (London)
internal validity
- control group, better comparison
correlational evidence
- experience and hippocampus size, no cause and effect
use of scanning
- scientific, empirical, valid, credible
functional recovery
from of plasticity
ability to move functions from damaged area after trauma to undamaged areas
brain copes better with indirect effects of brain damage e.g. swelling, haemorrhage
neural reorganisation
existing inactive neural pathways used for other purposes take over and carry out functions lost due to injury
neuronal unmasking
brain can rewire and reorganise itself by forming new synaptic connections close to area of damage
- dormant synapses (not enough input to be active) open connections to compensate for damage, new connections activated
quickly after trauma, then slows down, rehab may be needed
axonal sprouting
new nerve endings grow and connect to other undamaged nerve cells to make new neural pathways
reformation of blood vessels
veins, arteries and capillaries are repaired to maintain flow of glucose and oxygen to damaged area
recruitment of homologous areas
areas on opposite side of brain take on performance of tasks by damaged areas
if original area heals, function can return
denervation super sensitivity
neuronal axons that do a similar function to those damaged become easily aroused to compensate for loss of arousal in damaged area
functional recovery strengths
application
constraint-induced movement forces use of limb affected by stroke through restraint of unaffected limb
stimulates brain into reorganising itself
developed after research into neuroplasticity
research invaluable in providing interventions to aid recovery
functional recovery strengths
case study evidence
Danelli found that a 2.5 y.o. boy who lost most of left hemisphere recovered language skills over time
right hemisphere compensated
functions moved from left to right hemisphere (recruitment of homologous areas)
does show plasticity in redistributing functions to undamaged areas but did not have complete functional recovery - grammatical errors, slow at naming objects
BUT, is a case study, cannot be replicated as everyone’s brain will respond differently, plasticity easier in children
functional recovery weaknesses
maladaptive behavioural consequences
phantom limb syndrome in 80-100% of amputees
result of cortical reorganisation in somatosensory cortex
can result in negative sensory experiences e.g. burning, electric shock sensations, shooting pains and itching
beneficial in recovery, not always positive
functional recovery weaknesses
refutes age dependency
Elbert concluded that neural reorganisation capacity is greater in children, neural regeneration less effective in older brains
brain more plastic not fully developed, so functional recovery easier
implies that neurorehabilitation more successful in younger people, but still happens in older people
Bezzola demonstrated how 40 hrs of golf produced inrecread neural representation in motor cortex in middle-aged novices. contradicts age dependency as can still occur
can occur at any age, easier when younger
functional recovery weaknesses
individual differences
Schneider found that the more time people with brain injury spent in education (higher cognitive reserve) had greater chance of disability free recovery
strengthened brain and neural pathways, greater chance of recovery
fMRI
functional magnetic resonance imaging
measures blood flow during a task
works on premise that neurones in the brain that are most active use the most energy
produces a dynamic 3D map of brain
fMRI strengths
non-invasive
- no radiation or instruments inserted, risk-free
- allows more patients, more accessible, further data to develop understanding
good spatial resolution (1-2mm)
- smallest measure a scanner can detect, can discriminate between brain regions with greater accuracy. more valid and useful
fMRI weaknesses
poor temporal resolution (1-4 sec)
- accuracy in how quickly can detect changes in brain activity
- unable to predict brain activity accurately
do not provide direct measure of neural activity
- measures changes of blood flow, cannot infer causation
- unable to conclude whether brain region associated with function
only show localisation of function, limited in showing communication between areas, limited usefulness
EEG
electroencephalogram
measures electrical activity through electrodes
electrical charges graphed over time, indicating levels of activity
works on premise that info is processed as electrical energy in form of action potentials
detects epilepsy, sleep disorders and diagnoses disorders affecting brain activity, like Alzheimer’s
EEG weakness
electrical activity can be detected in several regions simultaneously
difficult to pinpoint exact region, hard to draw accurate conclusions
ERPs
event related potentials
uses electrodes attached to scalp
ERPs strength
enable determination of how processing affected by specific experimental manipulation
experimentally robust as eliminates extraneous neural activity
EEG/ERPs weaknesses
poor spatial resolution
only detects activity in superficial regions, no info on deeper regions
limited accuracy
uncomfortable with electrodes on scalp
unrepresentative readings as discomfort may affect cognitive responses
fMRI less invasive
EEG/ERPs strengths
non invasive
no radiation or insertion, risk free
more accessible, so more info gathered
cheaper than fMRI
more readily available, helps gain more info
good temporal resolution
readings every millisecond, record activity in real time
more accurate measurements
post mortem examination
study physical brain of person who displayed a particular behaviour that indicated possible brain damage
e.g. Broca examined brain of man who displayed speech problems, discovered area important for speech production
post mortem examination weaknesses
issue of causation
function deficit not necessarily linked to physical deficit
may have been due to other illnesses
extraneous factors can alter conclusions
death at different ages for many different regions
medication, age, time between death and examination are confounding
invasive, but patient is dead
ethical issues - informed consent, carried out on patients with severe psych defects, unable to provide informed consent
passive brain
post mortem examination strengths
provides detailed examination of anatomy and neurochemistry not possible otherwise
can access hypothalamus and hippocampus, insight into deeper brain regions
biological rhythm
cyclical changes in body activity
endogenous pacemakers
internal body clocks that regulate many bio rhythms
in absence of cues, are free-running
e.g. suprachiasmatic nucleus
exogenous zeitgebers
external cues that may influence bio functions
e.g. light
circadian rhythm
pattern of behaviours that occur approx every 24 hours and reset by environmental light levels e.g. sleep/wake cycle and body temperature
infradian rhythms
duration of over 24 hours
e.g. menstrual cycle
ultradian rhythms
duration of less than 24 hours e.g. stages of sleep
sleep-wake cycle
melatonin
peaks once every 24 hours in the night to incite sleep, drops during the day to prevent sleep
involved in onset of sleep as signals brain to slow functioning
suprachiasmatic nucleus
anterior hypothalamus
main endogenous pacemaker
connected to pineal gland and optic nerve
allows synchrony of circadian rhythms with external environment
pineal gland
underneath posterior corpus callosum
secretes hormone melatonin in response to light cues
light as exogenous zeitgeber
entrains sleep-wake cycle
signals SCN to increase or decrease melatonin release
sleep-wake cycle process
EYE takes in light
OPTIC NERVE carries light signals to brain
SCN detects light and signals pineal gland
PINEAL GLAND receives signals and controls release of melatonin
MELATONIN releases pineal gland and signals brain to reduce function
evidence for endogenous control of sleep-wake cycle
Ralph bred mutant hamster with 20 hour sleep wake cycle
when SCN cells transplanted into normal hamsters, cycle changed to 20 hours
supports SCN controlling cycle
evidence for exogenous control of sleep-wake cycle
woke participants in sleep study at various times and shone light on the backs of their knees
produced deviation in usual cycle of up to 3 hours
can absorb light through skin
light’s influence
core body temperature as a circadian rhythm
lowest in early morning 36
highest in early evening 38
sleep occurs when core temp starts to drop
alertness from body temp rising at end of sleep cycle
circadian rhythms strengths
research evidence
supports interaction between endogenous pacemakers and exogenous zeitgebers
Siffre’s temporal isolation study, 6 months in a cave, no exposure to natural light and sound
free-running bio clock settled to 25 hours. estimation of date when emerged differed by a month as experience of a day lengthened
demonstrates that without external light cues, circadian rhythms are free-running (SCN)
exogenous zeitgebers needed to keep us sychronsied with externa world
replicated, in first month, cycle were longer tha 24 hours and then varied randomly from 18-52 hours, suggests both endogenous and exogenous cues needed, not as free-running as originally suggested
circadian rhythms strengths
implications on functioning
Boivin reported that night workers experience reduced concentration at 6am, accidents and mistakes are more likely
low alertness due to high melatonin, low cortisol, low metabolic effect and less energy produced, body temp low, counterintuitive bio processes to being awake
research helped us understand negative effects when rhythms disrupted
circadian rhythms strengths
practical applications
Czeisler reported that work schedule satisfaction, subjective health estimates, personnel turnover and worker productivitu improve when shift patterns that consider circadian principles are introduced
implications to implement rotating shifts, sufficient time off to adapt rhythms leads to more beneficial work practices
circadian rhythms weaknesses
population validity
case study involving only one person
individual differences may affect rhythms
results cannot be generalised to wider population
limited in telling us much about circadian rhythms in general
circadian rhythms weaknesses
individual differences
Czieszler noted variance in circadian rhythms of people between 13 and 65 hours.
suggests it is too simplistic to say that a circadian rhythm is around 24 hours, suggests that we all follow same rhythmic patterns, when they vary significantly between individuals
circadian not appropriate - based on 24 hours being standard
infradian rhythms
cyclical pattern of longer than 24 hours
e.g. menstrual cycle (28 days)
endogenous control of menstrual cycle
pituitary gland releases FSH and LH into bloodstream
encourages egg cell in follice to grow and mature
follicle releasing oestrogen, inhibits FSH, releases more LH
increase in LH triggers release of egg (ovulation on day 14)
empty follicle releases progesterone, signalling womb lining to thicken with blood and nutrients
if fertilised blood not implanted, oestrogen and progesterone plummet, causing womb lining to fall away (menstruation)
exogenous control of menstrual cycle
menstrual synchronisation - when menstruating females who are in close proximity for an extended period of time tend to synchronise their monthly menstruation cycles
due to pheromones
pheromones
chemicals secreted
can affect others, like an external hormone
thought to be detected by olfactory system and emitted through sweat
research evidence for exogenous control of menstrual cycle
McClintock and Stern
studied 29 women with irregular period, controlled experiment
pheromone samples gather from 9 at different stages of menstrual cycles via cotton pad on armpit
pads then rubbed onto upper lip of other 20 ppts
68% of women experienced changes to menstrual cycle, bringing them closed to cycle of ‘odour donor’
supports idea that affected by external cues
infradian rhythms strengths
evolutionary advantage
female pregnancies within social group synchronised
share childcare, greater survival of offspring
HOWEVER, leads to competition for highest quality females
could negatively affect reproductive success, evolutionary disadvantage
do not understand why menstrual synchronisation occurs, descriptive but not explanatory
infradian rhythms strengths
research evidence
infradian rhythm of hormones involved influence other behaviours
Penton-Volk found that women expressed a preference for feminised faces at least fertile stage, and a more masculine face at most fertile stage.
indicates that sexual preferences motivated by infradian rhythms
HOWEVER, is socially sensitive
implies that some men are less reproductively desirable and less attractive
endogenous processes can have a significant impact upon multiple behaviour, not just physiological control of the menstrual cycle
infradian rhythms strengths
useful implications
Dalton suggested that premenstrual syndrome is associated with increase in accidents, lower academic performance, suicide and crime.
understanding of hormones is of great importance as can impact multiple behaviours and can have negative consequences
enhances understanding of women’s experience
can positively challenge when women’s behavior is pathologised through explaining that behaviour is a bio consequence of hormonal fluctuations
infradian rhythms weaknesses
methodological issues
Schank reviewed 8 studies that reported pheromone effects on menstrual cycles, other behaviour or physiological correlates in women and found serious methodological problems.
doubt cast on theory that pheromones can modulate length of menstrual cycle
idea of an infradian rhythm that can be exogenously infleunced lacks validity
ultradian rhythm
stages of sleep
lasts less than 24 hours and cycles through different stages multiple times in 24 hours
5 stages that alternate in 90 min cycles
light, deep and REM sleep
each cycle finished at each REM episode
varies in levels of brain activity
as sleep progresses, REM stages last for longer and stay between REM and stage 2
last cycle is the emergent cycle, wake from stage 2 or REM
stage 1 brain activity
alpha waves (starting to relax but still awake)
theta waves (after falling sleep)
slow and rhythmic
stage 2 brain activity
theta waves
bursts of high frequency waves
K-complexes - large waves in response to environmental stimuli
20 mins, easily awoken
heart rate slows, core body temp decreases
stage 3 brain activity
delta waves
start to slow, become higher in amplitude
15 mins, difficult to wake, deep sleep
less response to environmental stimuli
muscles relax, blood pressure and breathing rate slow
stage 4 brain activity
delta waves
40 mins, hard to wake, deep sleep
low temp, HR, BP and metabolic rate, growth hormones released
REM brain activity
similar to waking - high brain activity
vivid and frequent dreaming
sleep paralysis - arm and leg muscles temporarily paralysed, preventing acting out of dreams
paradoxical sleep - brain and body systems become more active (HR, temp, BP increase, eyes twitch rapidly), muscles become more relaxed
ultradian rhythms strengths
research evidence
Dement and Kleitman monitored sleep patterns of 9 adults. Ppts were awoken at various points, and asked to report if they had been dreaming when they were woken. Ppts frequently described dreams when woken in REM but less in nREM.
supports idea of distinct stages, clear difference in brain activity and higher association of dreams with REM sleep. At least 2 stages - REM, non-REM
empirical and objective, theory has validity
ultradian rhythms strengths
some stages may be more significant than others
REM-rebound effect shows that after sleep-deprivation, people had an increase in frequency, depth and intensity of REM and amount of lighter stages decreases.
Randy Gardner experienced 11 days of sleep deprivation and recovered a higher proportion of REM and stage 4.
suggess that some are of greater importance, flexibility in experiences of sleep stages to prioritise
greater significance for mental and physiological wellbeing
ultradian rhythms weaknesses
methodological issues
controlled lab setting using EEG machne
unnatural setting can reduce ability to sleep - unrepresentative and unrealistic (lacks eco validity and mundane realism)
research lacks validity, true insight not attainable
ultradian rhythms weaknesses
nomothetic
assumes that all people have the same cycles
Tucker found significant differences between participants of duration of each stage, particularly 3 and 4.
suggests that sleep cycle rhythms vary between individuals
outlining stages of sleep as having set order, not valid, variances
