Biopsychology

central nervous system

-brain and spinal cord

-acts as body’s control center: recieving, processing, and responding to sensory info

-co ordinating motor activity

peripheral nervous system

-divided into somatic NS and autonomic NS

-consists of nerves outside the brain and spinal cord

-relays information between CNS and rest of the body

somatic nervous system

-voluntary movement

-nerves carrying messages to the eyes, ears and skeletal muslces

-transmits info b/w CNS and senses

autonomic nervous system

-controls involuntary movement

-info from CNS to internal organs and from non skeletal muslces.

-split further into sympathetic and parasympathetic NS

sympathetic nervous system

-fight or flight, activated in situations requiring arousal and energy

parasympathetic nervous system

allows body to return to homeostasis after the threat of danger has passed

dendrite

allows electrochemical messages/impulses to arrive at the neuron through the dendrites

axon

carries signal away from cell body

myelin sheath

-fatty substance surrounding axon cable

-speeds to rate at which nerve impulses are carried

axon terminal

-when an impulse reaches end of axon, it is passed to another neuron, gland or organ via axon terminal

synaptic transmission

1. electrical impulses passed through axon of a neuron to synaptic terminal

2. electrical impulse causes calcium channels to open, in turn vesicles containing NT release into synapse. They then move acros the synapse

3. NT bind to receptors on the post synaptic neuron

4. NT can either be inhibitory (less likely to fire) or exicitatory (more likely to fire)

reuptake channel

neurotransmitters sent back to presynaptic neuron via reuptake channel to be use d again

enzymes

may break down neurotransmitters

sensory neurons

send signals to CNS about sensory experiences

afferent=carry signals away from organ to brain

long dendrites, short axons

motor neurons

efferent=from the brain/spinal cord to muscles and glands

help produce movement/response

long axons, short dendrites

relay neurons

form connections between other neurons

all neurons in CNS

over 100 billion

nodes of Ranvier

help electrical impulse jump from section to section to increase speed of electrical impulse

endocrine system

network of glands across the body that secrete chemical messengers (hormones) into the bloodstream

hypothalamus

connected to pituitary gland, stimulates and releases hormones from it.

pituitary gland

-oxytocin, TSH, ACTH

• ‘master gland’.

ACTH signals action for adrenal glands

thyroid gland

-thyroxine

-regulates metabolism

parathyroid gland

-parathyroid hormone

-increases concentration of calcium in the blood from kidneys and bone

pancreas

-insulin

-absorption of glucose from the blood into fat, liver, and skeletal muscle cells

adrenal glands

adrenaline, noradrenaline

reacting to threat via flight or fight

ovaries (female)

oestrogen and progesterone

development and regulation of the female reproductive system and secondary sex characteristics

testes (male)

testosterone

development of male reproductive system

pineal gland

melatonin

regulates sleep wake cycle

fight or flight

1. threat detected via the eyes, information sent to amygdala

2. amydala signals hypothalamus, which communicates with the SNS and instructs pineal gland to release ACTH

3. The release of ACTH causes the adrenal glands to release adrenaline and noradrenaline

4. physical changes to prepare body for threat: increased heart rate, dialated pupils, blood flow redirected from digestion to muscles.

5. once the threat has passed, the parasympathetic NS returns the body to homeostasis

localisation of function theory

different functions of the brain are localised in specific areas and are responsible for different activities

motor area

frontal lobe

regulates movement

somatosensory area

parietal lobe

processes sensory info

visual area

occipital lobe

recieves/processes visual info

auditory area

temporal lobe

analysis of speech

Broca’s area

frontal, left hemisphere

speech production

Broca’s aphasia: slow, influent speech

Wernike’s area

temporal lobe, left hemisphere

language comprehension

cerebral cortex

covers all inner parts of the brain

Petersen et al (1988): evidence of localisation

-brain scans showing Wernike’s area active during listening task and Broca’s during a reading task.

Dougherty et al (2002)

-44 OCD patietns who had undergone a cingulotomy, severing the cingulate gyrus

1/3 of patient’s symptoms significantly improved and 14% showed partial improvement

cingulate gyrus thought to be more active in people with OCD

Clive Wearing

damage to semantic but not procedural memory

suggests localisation b/c if the function was spread throughout entire brain then we would expect more global effects on memory

Lashley (1950)

-higher cognitive process like learning and decision making not localised but distributed holistically

-taught rats to solve a maze, using frontal cortex.

-10-50% of the area removed and observed whether they could still navigate maze

-no particular area shown more important in ability to complete maze, could still solve it despite legions.

-learning too complex to be localised to one area, supports more mulitfunctional theory

Plasticity

ability of the brain to be flexible and adapt to new situations

if a certain area is damaged, other areas can take over the functions

15,000

number of synaptic connections to other neurons which peaks at age 2-3

synaptic pruning

as we age, connections we don’t use are deleted and the ones we do use are strengthened

Maguire et al (2000): London taxi drivers

-greater volume of grey matter in posterior hippocampus in London taxi drivers due to extensive navigation experience.

-this part of the brain associated with spatial and navigational skills

-the learning drivers undertake alters the strucutre of the brain.

-positive correlation between how long they’d been in the job and amount of grey matter

evaluating Maguire (2000)

-correlational so causation can’t be established.

-spatial awareness caused them to be taxi drivers due to naturally bigger hippocampus.

Kuhn et al (2013)

-significant increase in grey matter in various regions of brain after participants played video games over a period of 2 months for 30 mins/day.

-experience can lead to structural changes in the brain

Draganski (2006)

imaged brains of medical students 3 months before and after final exams

learning induced changes seen to have occured in posterior hippocampus and parietal cortex

Mechelli (2004)

larger parietal cortex in bilingual individuals, suggesting that learning a second language can lead to structural changes in the brain.

functional recovery

brain able to recover from trauma caused by physical injury

unaffected areas can compensate for areas lost/damaged.

axonal sprouting

growth of new nerve endings which connect with undamaged nerve cells to form new neuronal pathways

reformation of blood vessels

blood flow increased to affected area

recruitment of homologous areas

similar areas on the other side of the brain take over specific tasks

Danelli (2013)

-EB, whose entire left hemisphere was removed due to non cancerous tumor at 2 years.

-by 5 years, language fluency improved to intensive rehabilitation and by 17 despite minor problems with grammar, language appeared virtually normal

evaluation of plasticity/functional recovery

-understanding contributed to field of neurorehabilitation

-helps those who suffered brain trauma

-we know that spontaneous brain recovery slows down after a few weeks so we know when PT may be best started.

-evidence suggests brain may partially fix itself but intervention may be required if full recovery to be achieved.

evaluating plasticity and runctional recovery

some brain adaptations may be maladaptive

prolonged drug use results in poorer cognitive functioning and increases risk of dementia

60-80% of amputees develop phantom limb syndrome, causing unpleasant sensations arising from cortical reorganisation in somatosensory cortex

can be negative consequences of brain rewiring but there are treatments that help individuals to manage these negative effects.

evaluating plasticity and functional recovery

functional recovery reduces with age and affects speed of recovery

• Marquez de la plata (2008): following brain trauma, older patients regained less function in treatments than younger people and more likely to decline in function for the first 5 years after the trauma

• Bezzola et al (2012): 40hrs of golf training produced changes in neural representation of movement in those b/w 40-60. motor cortex activity reduced for novice golfers vs. control group.

• supports view that neural plasticity can continue throughout lifespan.

evidence suggesting women recover better from brain injury b/c function not as lateralised.

evalating plasticity/functional recovery

-level of education can influence how brain recovers after trauma

-Schneider (2014): the more time brain injured patients had spent in education the greater the chances of full recovery

-suggests cognitive reserve could be important factor in brain recovery after trauma.

lateralisation

brain divided into 2 hemispheres (left and right).

language-left hemisphere as both Wernike’s and Broca’s here, suggesting lanuage is subject to hemispheric lateralisation.

corpus callosum

connects two hemispheres like a bridge that allows both sides of the brain to communicate with each other.

commissurotomy: corpus callosum severed to treat severe epilepsy.

Sperry: procedures

-used T-scope to test each hemisphere in isolation of the other

-participant asked to focus on a fixation point and then image/word projected for 1/10th of a second to one or both visual fields

-equipment enabled participants to be able to pick up/match objects out of sight.

-’normal brain’: corpus callosum shared info b/w both hemispheres which gave a complete picture of the visual world

-when split brain patients only shown things to one hemisphere, info couldn’t be conveyed

Sperry:findings

1. when picture/word projected to right visual field (info processed in left hemisphere), patient could easily describe what had been shown

2. when picture/word showed to left visual field, the patient couldn’t describe it, saying nothing was there.

   • language processed in left hemisphere as patients could only describe what they saw when projected to right visual field.

3. left visual field: could use left hand to point to a matching object or picture.

   • right hemisphere had processed info and controls left hand, can’t verbalise what was shown

4. object placed in right hand could be easily described in speech or writing but objects placed in left couldn’t be. When object placed in a grab bag with other objects, patient can retrieve object with left hand, supporting hemispheric lateralisation

evaluation of split brain research

experimental, involves use of specialised equipment that objectively measures lateralisation of function

very quick projection means split brain patients couldn’t move eyes across image and ensures visual information only processed by one field

internal validity

evaluation of split brain research

standardised procedures allow for replication

same procedure has revealed same results

evaluation of split brain research

control group were people with no history of epilepsy

could be unique changes in brain resulting from epilepsy influencing results

better control group would have been people with epilepsy who hadn’t undergone the split brain procedure.

evaluation of split brain research

small sample size, difficult for results to be generalised

small sample sizes unavoidable as commissurotomy is rare

evaluation of split brain research

artificial conditions

in real life a severed corpus callosum can be compensated for by unrestricted use of two eyes so findings cannot be applied to how split brain patients function in everyday tasks.

evaluation of split brain research

-useful in investigating/demonstrating lateralisation of function, improving understanding of each hemisphere

fMRI

-detects changes in blood oxygenation

-3d images prodcued showing which brain parts involved in particular mental processes, allows understanding of localisation of function

strengths of MRI

-no radiation, so risk free

-non invasive and straightforward

-images with high spatial resolution so provides clear picture of localisation.

weaknesses of MRI

-expensive, researchers can only use a small sample size impacting validity and generalisability.

-poor temporal resolution, not showing changes over time

-cannot tell us exact activity of individual neurons

EEG

measures electrical activity in brain via electrodes

scan recording represents brainwave patterns

uses amplitude and frequency

strengths of EEG

-valuable in diagnosing conditions like epilepsy and schizophrenia due to detecting differences in brain activity

-contributed to understanding of sleep stages/problems

-cheap

-high temporal resolution as records activity in real time

weaknesses of EEG

-can’t detect activity in deeper brain regions

-not useful in pinpointing the exact source of neural activity

ERPs

stimulus presented to participant and researcher looks for activity related to stimulus

uses electrodes like an EEG

strengths of ERPs

-more specific than EEGs to measurement of neural processes

-provide continous measure in response to stimulus, producing quantitative data

-researchers have been able to ID ERPs of mental health issues like phobias

weaknesses of ERPs

-lack of standardisation in ERP methodology

-may not always be possible to completely eliminate background noise and extraneous material-questionable validity.

Post mortem examinations

analysis of brain after death

-used in people with rare conditions and unusual deficits

-areas of damage investigated PM to establish likely cause of problem

strengths of Post mortem examination

-vital in providing early understanding of key processes (Broca’s and Wernike’s disocvered using PM)

-improved medical knowledge and helps generate hypotheses for future study

weaknesses of PM examination

causation: observed damage may not be the cause of deficits

ethical concerns, lack of consent before death.

circadian rhythms

-cycles occuring once every 24 hours

-sleep wake cycle

infradian rhythms

-cycles occuring longer than 24 hours

-weekly, monthly, annually

-menstruation

ultradian rhythms

-lasts fewer than 24 hours

-sleep cycles

endogenous pacemakers

internal body clock setting body rhythms like sleep

suprachiamatic nucleus (SCN)

exogenous zeitgeber

external cues like light

how do endogenous pacemakers and exogenous zeitgebers influence circadian rhythm?

-SCN recieves info about light directly, passes info to pineal gland

-pineal gland releases melatonin based on this information

-more daylight=less melatonin, less=more

-even in absence of light, SCN generates a rhythm related to protein production (when certain level of protein reached message passed to pineal gland, melatonin will be released/inihibited).

Siffre (1962)

-spent 2 months living in complete isolation in a cave

-deprived of natural light, a clock, calendar and sound

-slept and ate when body told him to

-resurfaced in mid-September thinking it was mid August

-lack of external cues made him think a day was longer than it was

-performed same sort of thing for six months in a cave in Texas: both cases saw circadian rhythm settle to around 25 hours (showing circadian rhythm adapts to light levels and exogenous zeitgebers).

Aschoff and Wever (1976)

-participants spent 4 weeks in a WWII bunker

-sheilded from natural light, temp changes

-artificial light available

-displayed circadian rhythm of 25 hours

-natural sleep/wake cycle may be slightly longer than 24 hours but we use natural light to entrain our pacemakers to align with 24 hour clock

Folkard (1985)

-12 participants agreed to live in adark cave for 3 weeks

-researchers manipulated clock, participants would sleep at what they thought was 11:45pm and awake at 7:45am

-over the course of the study, the clock was sped up, a normal 24 hour day actually only lasted 22 hours.

-one participant adjusted comfortably, suggesting a strong free running circadian rhythm that cannot be easily be overridden.

evaluation of research into circadian rhythm

-small sample sizes and generalisation

-even one individual (Siffre)

-people involved may not be representative

evaluation of research into circadian rhythm

-confounding variables: in Aschoff and Weaver’s study they had access to artifical light

-Siffre would turn on a light every time he woke up which stayed on til he went to be.

-Czeisler (1999): suggests artifical light can have an influence.

evaluation of research into circadian rhythm

individual cycles can vary

some people have a natural preference for going to bed early and waking early, others the opposite.

age differences in sleep/wake patterns.

innate differences complicate generalisation

evaluation of circadian rhythm research

-research has provided a better understanding of the consequences of disrupted circadian rhythms

-night workers experience reduced concentration around 6 am-makes accidents/mistakes more likely.

-economic implications, changes in shift patterns manage productivity and welfare.

Ralph (1990): Hamster study

-removed and transplanted SCNs from hamsters

-mutant hamsters bred to have a CR of 20 hours, SCN cells from these hamsters transferred to brains of normal hamsters with 24hr CR.

-normal hamsters adapted same 20hr CR as donor.

-hamsters with nocturnal patterns had SCNs replaced with those of hamsters active during the day and the hamsters exhibited nonnocturnal behavior.

Campbell and Murphy (1998)

-15 participants woken up at various times and a light pad shone on the back of their knees

-researchers found a change in sleep/wake cycle of up to 3 hrs in some cases

evaluation of exogenous zeitgeber/endogenous pacemaker studies

-ethics: hamsters harmed during study

-generalisable?

-C&M’s findings have yet to be replicated

Reinberg (1967)

-one participant spent 3 months in a cave with only light from a small lamp

-her menstrual cycle shortened from 28 days to 25.7 days.

-suggests lack of light affected woman’s menstrual cycle

McClintock and Stern (1998)

aim: showing menstrual cycle influenced by pheromonal secretions from other women

29 female uni students

samples of pheremones gathered from 9 of the women at different stages of their cycles (cotton pad placed under armpit). Pads treated with alcohol and frozen

odour from these pads inhaled by other 20 women

day 1: pads from start of cycle, day 2: pads from second day etc.

McClintock and Stern (1998) findings

-when experimental group inhaled secretions from women who were about to ovulate, menstrual cycles became shorter

-when they inhaled secretions from women who’d just ovulated, cycles got longer.

-on 68% of occasions, recipients of sweat donation experienced changes to cycle which brought them closer to donor.

-suggests role of exogenous zeitgebers in infradian rhythms

evaluation of infradian rhythms

-numerous factors other than pheromones that could change a woman’s cycle.

stress, diet, exercise may act as confounding variables

research based on small sample

relies on women self reporting own cycle.

evalaution of infradian rhythms

recent replication of research between women in close proximity and cycle hasn’t replicated evidence

reduced reliability