biopsychology Flashcards
2 key features of the nervous system
- to collect, process and respond to information in the environment
- to co-ordinate the working of different organs and cells in body
structure of the CNS
-made up of brain and spinal cord
-brain is centre of consciousness
-outer layer is cerebral cortex which distinguishes higher functions
-divided in to 2 hemispheres
function of the CNS
-spinal cord is extension of brain responsible for reflex actions
-passes messages to and from brain, connecting nerves to PNS
2 sub units structure of PNS
subdivided into;
1. autonomic nervous system (ANS) governs vital function in body such as breathing digestion and sexual arousal
2. somatic nervous system (SNS) governs muscle movement and receives info from sensory receptors
key features of endocrine system
-works alongside nervous system to control vital functions through hormones
-works more slowly than nervous system
endocrine system- glands
-organs which produce hormones
-key endocrine gland is pituitary gland located in brain
-it controls release of hormones from all other glands in body
endocrine system- hormones
-secreted in the bloodstream
-effects any cell in body that has receptor for that particular hormone
fight or flight- part 1
-stressor perceived by hypothalamus which activates pituitary
-sympathetic nervous system is aroused
fight or flight- adrenaline
-the stress hormone
-released from adrenal medulla in to bloodstream
-this delivers aroused state
-increased heart rate, dilated pupils, decreased saliva
fight or flight- part 2
-response is immediate and automatic
-parasympathetic nervous system takes over once threat has passed, returns body to its resting state
neurons
-transmit signals electrically and chemically to communicate
sensory neurons
-carry messages from the PNS to the CNS.
-they have long dendrites and short axons
relay neurons
-connect sensory neurons to motor neurons
-short dendrites and axons
-most are in brain and visual system
motor neurons
-connect CNS to effectors such as muscles and glands
-short dendrites and long axons
structure of a neuron
-cell body (includes nucleus)
-dendrites (carry nerve impulses from other neurons to the body)
-axon (carry electrical impulses away from cell body) covered in myelin sheath
-terminal buttons (at end of axon to communicate with next neuron across synapse)
electrical transmission- firing of a neuron
-when activated, inside of cell becomes positively charged for a split second causing action potential
-this creates the electrical impulse
synapse
-extremely tiny gap between 2 neurons
events that occur at synapse
-signals transmitted chemically across synapse
-electrical impulse reaches end of neuron (presynaptic terminal) it triggers release of neurotransmitter from synaptic vesicles
-after gap, it is taken up by postsynaptic receptor site on next neuron
-converted back in to electrical message
neurotransmitters
-chemicals which diffuse across synapse to next neuron
-each has its own specific molecular structure that fits in to postsynaptic site like lock and key
types of neurotransmitters
- acetycholine- found where m neuron meets muscle, causing muscle to contract
2.serotonin- affects mood and social behaviour
adrenaline
-excitatory effects, increasing positive charge of postsynaptic neuron, making it more likely to fire
serotonin
-generally inhibitory effects, increasing negative charge, making it less likely to fire
dopamine
-unusual as it has equally inhibitory and excitatory effects
summation- excitatory and inhibitory
-excitatory and inhibitory influences are summed and must reach threshold for postsynaptic neuron to be triggered
holistic theory
-19th century holistic theory suggested all parts of brain were involved in all processing
holistic theory replaced by localisation
-specific areas of the brain are linked to specific physical and psychological functions
-if an area of the brain is effected function of that area is too
lateralisation
some physical and psychological functions are controlled by a particular hemisphere
hemispheres
LH (speech)- controls right side of body
RH (visual and emotion)- controls left side of body
cerebral cortex (outer layer)
-highly developed area
cerebral cortex- motor area
-at back of frontal lobe in both hemispheres
-controls voluntary movement
-damage may cause loss in fine motor movement
cerebral cortex- somatosensory area
-at front of parietal lobes
-processes sensory info from skin
-amount of somatosensory area devoted to a body part determines its sensitivity
cerebral cortex- visual area
-in occipital lobe at back of brain
-right visual field sends info to left visual cortex and vice versa
cerebral cortex- auditory area
-in temporal lobe
-analyses speech based info
-damage may cause partial hearing loss
language centres- brocas area
-speech production
-identified by Broca in 1880s
-in left frontal lobe
-causes brocas aphasia, slow laborious speech
language centres- wernickes area
-language understanding
-identified by wernicke in 1880s
-wernickes aphasia produces meaningless non sesne speech and has trouble understanding others
what is hemispheric lateralisation
-means the brain is lateralised in to two seperate hemispheres
localised meaning
-some brain functions are localised and appear in both the right and left hemisphere
-e.g. auditory, visual and motor
localised and lateralised
-2 main language centres are in LH
-brocas area (left frontal lobe)
-wernickes area (left temporal lobe)
-RH produced rudimentary words but provides emotional context
cross wired
-right hemisphere controls left side of the body and vice versa
cross wired visual field
-LVF is connected to the RH and vice versa
-this enables the visual areas to compare the slightly different perspective from each eye
sperry (1968) split brain research- procedure
-2 hemispheres surgically seperated by cutting corpus callosum
-used to treat severe epliepsy
-image presented to each hemisphere and asked to describe it
sperry (1968)- split brain research- findings
object shown to RVF- pps can describe what is seen
object shown to LVF- cannot name objects as no lang centre in RH
-shows how certain functions are lateralised in brain
plasticity
-(Gopnick et al 1999) during infancy brain experiences rapid growth in synaptic connections
-as we age, rarely used connections are deleted and frequently used are strengthened (synaptic pruning)
-this can happen at anytime due to learning and experience
plasticity- taxi driver study
- Maguire et al (2000) found more volume of grey matter in posterior hippocampus in taxi drivers than control group
-this part of brain is linked with spatial and navigational skill
-more pronounced the longer they had been in job
plasticity- supporting learning research
-Draganski et al (2006) imaged brain of med students 3 month before and after exams
-learning induced changes seen in posterior hippocampus and parietal cortex as a result of learning for the exam
brain response to trauma
-healthy brain areas take over function of damages areas
-this occurs quickly (spontaneous recovery)
-when it slows, the person may require rehabilitative therapy
brain ‘rewires’ itself
–able to rewire and reogranise itself after trauma by forming new synaptic connections
-secondary neural pathways that would not be typircally used are activated
structural changes in brain after trauma- axonal sprouting
growth of new nerve endings which connect with other undamaged cells to form new neuron pathways
structural changes in brain after trauma- denervation supersensitivity
-axons that do a similar job become aroused to a higher level to compensate for the ones that are lost
structural changes in brain after trauma- recruitment of homologous areas
-the opposite side of the brain takes over specific tasks
medical techniques used to investigate brain localisation
-techniques used to investigate brain are used to diagnose illness
fMRI- highlights active areas of brain
-detects changes in both blood oxygenation and neural activity
-when an area is more active it takes up more oxygen
-produces a 3D image of which parts of the brain are active and therefore must be involved in certain mental processes
EEG- shows overall electrical activity
-measures electrical activity within the brain
-brainwave pattern shows overall activity
-use as diagnostic tool, usual patterns may be signs of things such as epilepsy or tumors
ERPs- brainwaves related to particular events
-what is left when all extraneous brain activity from EEG is filtered out
-ERPs are triggered by particular events
-many different forms of ERP are linked to cognitive processes
post mortem exams
-areas of brain examined to establish likely cause of deficit or disorder that the person experienced
-may involve comparison with a neurotypical brain
circadian rhythms- governed by
- internal biological clocks (endogenous pacemakers)
- external changes in environment (exogeneous zeitgebers)
-some occur many times a day ‘ultradian’
-others take more than a day to complete ‘infradian’
how long does circadian rhythm last
-24 hours
sleep/ wake cycle
EZ- drowsy at night and alert during day shows effect of daylight
EP-biological clock has no influence of external stimuli
-
The superchiasmatic nucleus
-SCN lies just above optic chiasm which provides info to eyes about light
-SCN governs basic rhythm
-EZ (light) can reset SCN
Siffre- free running circadian rhythm
-long periods in dark caves to examine effects of free running biological rhythms
-2 month in 1962 and 6 month in 70s
-settled down after 25 hours
-had regular sleep/ wake cycle
Aschoff and Wever- carcadian rhythms
-pps spent 4 weeks in ww2 bunker with no natural light
-one person (sleep wake cycle 29 hours, c rhythm between 24-25)
-bunker suggests natural cycle may be slightly longer than 24 hours
-but this is entrained by EZ such as daylight and meal times
Folker et al- EP vs EZ
-1985, 12 pps in cave for 3 weeks, going to bed when clock said 11.45pm and waking up 7.45
-researchers gradually sped up clock to 22 hour days
-only one pp adjusted
-shows strong circadian rhythm is not controlled by EZs
Infradian rhythms- menstrual cycle
-28 days i.e. less that one cycle in 24 hours
-rising oestrogen cause ovary to release egg (ovulation)
-progesterone then helps womb lining thicken ready for pregnancy
-if pregnancy does not occur, egg is absorbed and womb lining comes away (period)
EZs synchronise menstrual cycles
-Stern and McClintock 1998 studies 29 women with irregular periods
-phermones were taken from them at differenct stages of cycle under srmpits
-these werer later rubbed with alcohol and later rubbed on upper lips of others
-68% of women experienced changes to their cycle
seasonal affective disorder
-lack of activity and low mood with a seasonal pattern
-symptoms during winter because daylight hours become shorter
SAD may be caused me melatonin
-pineal gland secretes melatonin during the night
-in winter this lasts longer and has a knock on effect on production of serotonin in brain
ultradian rhythms- more than one cycle in 24 hours
-sleep patterns occur in 90 min periods
-divided in to 5 stages each categorised by different levels of brainwave activity using EEG
stage 1 and 2 of sleep
1- brainwaves high frequency with short amplitude, alpha waves
2-occasional random changes in pattern (sleep spindles)
stages 3 and 4 of sleep
-deep sleep/ slow wave sleep (SWS)
-individual waves have lower frequency and higher amplitude
-difficult to wake
stage 5 of sleep
-REM sleep
-body is paralysed but brain resembles that of an awake brain
-brain produces theta waves
-rapid eye movement
-dreams often
