Biopsychology Flashcards
The nervous system - AO1
Nervous system - a specialised network of cells, fast-acting and electrical/chemical internal communication system.
CNS - Brain (divided into hemispheres, cerebral cortex). Spinal cord - passes messages to and from brain - connects nerves to PNS - reflexes.
PNS - transmits messages to and from CNS via neurons.
Autonomic nervous system - governs vital functions - heartrate, digestion etc. Involuntary. Split into sympathetic and parasympathetic.
Somatic nervous system - muscle movement, receives sensory information from sensory receptors. Under conscious control.
The endocrine system - AO1
Glands produce hormones. Hormones secreted into bloodstream to have an effect on a target organ. E.g. thyroid > thyroxine. Thyroxine affects metabolic rate, which affects growth rate. Pituitary is master gland.
Fight or flight. Sympathetic arousal: stressor ~> hypothalamus ~> pituitary ~> adrenal gland (adrenal medulla) ~> adrenaline. Adrenaline leads to increased heart rate, faster breathing, sweating, inhibits digestion. Parasympathetic state - body returns to rest and digest.
Structure and function of neurons - AO1
Sensory - PNS to CNS, long dendrites - short axons. Cell body in middle. Located in clusters called ganglia.
Motor - CNS to effector, short-long
Relay - sensory to motor or other, short-short. Located in the brain. Cell body by dendrites. 97% of neurons.
Structure - cell body contains nucleus, genetic material. All have dendrites. Dendrites carry nerve impulses from neighbouring neurons to cell body.
Axon covered in myelin sheath, divided by nodes of Ranvier. Sheath protects the axon and speeds up electrical transmission. Terminal buttons at the ends of axons.
Electrical transmission - when a neuron is resting, the inside is negatively charged. Activated by stimulus, inside becomes positive, leads to action potential. Creates electrical impulse.
Synaptic transmission - AO1
Synapse - neurons separated by tiny gap.
Chemical transmission - neurotransmitter released from synaptic vesicle into synapse, taken up by postsynaptic receptor site on receiving dendrite. Process of diffusion - high to low concentration. Converted back into electrical impulse and carries on.
Excitation and inhibition - positive or negative effect on postsynaptic neuron - makes it more or less likely to fire - adrenaline and serotonin.
Summation - impulses are added up, net effect is excitatory or inhibitory.
Localisation of function in the brain - AO1
Localisation vs. holistic theory - are brain functions specific to areas or across the whole brain.
Cerebral cortex - outer layer of both hemispheres. Frontal, parietal, occipital and temporal lobes. Motor area located at back of frontal lobes - controls voluntary movement contralaterally. Front of parietal lobes - somatosensory area. Most receptors in hands and face. Visual area in occipital lobe - contralateral. Auditory area in temporal lobe - speech based information.
Language centres - Broca’s area related to production (left frontal) - ‘tan.’ Wernicke’s related to comprehension (left temporal)
Localisation of function in the brain - AO3
+ Damage to brain areas associated with disorders. Isolation of cingulate gyrus (cingulotomy) improves OCD in 30% of participants.
+ Evidence from brain scans - Broca’s area active during reading task - Wernicke’s during listening task. Peterson - semantic and episodic areas identified in prefrontal cortex.
C.P - learning in rats is holistic, not localised (Lashley) - maze study. Removed 10-50% cortex.
- Language localisation questioned - multiple pathways - not just Broca and Wernicke. Only 2% of psychologists think just those areas. Language distribution more holistic - language streams in the thalamus.
Hemispheric lateralisation - AO1
Some functions localised (e.g. vision) and some lateralised (language).
Language areas in LH (for most)
LH is the analyser, RH is the synthesiser. RH can only produce rudimentary words but gives emotional context.
Motor areas are contralateral.
Visual areas are contralateral and ipsilateral, LVF of both eyes to RH and RVF to LH. Same for auditory areas.
Hemispheric lateralisation - AO3
- One brain - certain hemispheres dedicated to certain tasks but no dominant hemisphere. Idea of analyser and synthesiser works, but ‘left-brained’ doesn’t exist.
+ Hemispheres process information differently - looking at whole forest - RH more active. Looking at finer detail - LH dominated.
Split-brain research - AO1
Procedure - 11 participants, split-brain operation for epilepsy.
Findings - object shown to RVF (LH) - person describes object. Shown to LVF (RH) - ‘nothing there.’
Object shown to LVF (RH) - nothing there but can select item with left hand.
Pinup picture to LVF - participant giggles but reports nothing. Silent but emotional.
Conclusions - lateralised brain, LH verbal and RH ‘silent’ but emotional.
Split-brain research - AO3
- Generalisability issues - epilepsy is a confounding variable when comparing participants to a control. Differences could be a result of it.
C.P - research support from Luck et al - split brain participants faster at odd one out - LH’s better cognitive skills ‘watered down’ by RH. - Ethical issues - participants may not be able to give fully informed consent due to trauma following corpus callosotomy. However, operation was not done for purpose of experiment.
Plasticity - AO1
Research suggests that neural connections can change or new connections can be formed. During infancy, brain experiences rapid growth, peaking at 15000 synaptic connections at 2-3 years. Often used connections are strengthened, rarely used ones are deleted - synaptic pruning - enables lifelong plasticity.
Research - Maguire taxi drivers - hippocampus changes structure after learning The Knowledge. More grey matter - associated with spatial and navigational skills.
Changes in hippocampus and parietal cortex after and before exams - Draganski.
Plasticity - AO3
- Negative plasticity - drug use may cause neural changes - poorer cognitive functioning and dementia. Phantom limb syndrome due to reorganisation in somatosensory cortex.
+ Plasticity may be life-long. Plasticity reduces with age, though Bezzola showed how golf training caused neural changes in over-40s - more motor cortex activity.
Functional recovery of the brain after trauma - AO1
Healthy brain areas take over lost functions after trauma, happens quickly, then slows down after several weeks.
What happens? - new synaptic connections, secondary pathways ‘unmasked.’
Axonal sprouting- the growth of new nerve endings which connect with undamaged ones.
Denervation supersensitivity - axons that do a similar job become aroused to a higher level to compensate. Can have negative consequences like oversensitivity to pain.
Recruitment of homologous brain areas. Similar areas on the other side of brain take on damaged tasks eg. Broca’s area.
Functional recovery of the brain after trauma - AO3
+ Real-world application - knowledge of axonal sprouting leads to constraint-induced movement therapy for stroke victims - using affected part of body while unaffected part restrained.
- Cognitive reserve affects functional recovery - 40% disability-free recovery for people with 16 years education, 10% DFR for those with less than 12 years.
Ways of studying the brain - AO1
fMRI - detects changes in oxygenated blood flow to show active areas (where more oxygen is consumed.) Produces a 3d image.
EEG - measures brainwave patterns from thousands of neurons via electrodes.
ERP - types of brainwave triggered by particular events filtered out from EEG recordings.
Post-mortems - study of brain after death, in order to link brain areas to observed behaviour deficits.
