biopsychology

• central nervous system - brain (cerebral cortex is outer layer), highly developed in humans. spinal chord connects brain to PNS, reflex actions
• peripheral nervous system - autonomic nervous system (sympathetic and parasympathetic). somatic nervous system (body)
• glands and hormones - hormones distributed in the blood stream. pituitary gland is the master gland
• flight or flight - sympathetic arousal

  pituitary --> adrenal gland --> adrenaline
• localisation versus holistic theory - are brain functions in specific areas or across the whole brain?
• hemispheres of the brain - brain (cerebrum) divided in half. each hemisphere controls the opposite side of the body = laterialisation
• motor, somatosensory, visual and auditory centres - each of the hour lobes of the brain (frontal, parietal, occipital and temporal lobes) is linked to different functions
• language centres of the brain - Broca's related to production (left frontal), Wernicke's related to understanding (left temporal)
• evaluate the localisation function of the brain

  • evidence from neurosurgery
  • evidence from brain scans
  • language localisation questioned
  • case study evidence
• evidence for neurosurgery - isolation (severing connections) of cingulate gyrus (cingulotomy) improves OCD in 30% of participants (Dougherty et al)
• evidence for brain scans - Broca's and Wernike's area identified (Petersen et al), semantic and episodic areas identified (Tulving et al)

  counterpoint - learning in rats is holistic not localised (Lashley)
• language localisation questioned - multiple pathways (e.g right hemisphere and thalamus), not just Broca's and Wernike's (Dick and Tremblay)
• case study evidence - unique case study supporting localisation (e.g Phineas Gage) but may lack generalisability and be subjective
• types of neurones - sensory, relay and motor neurons
• structure of a neuron - cell body contains nucleus, has dendrites. axon covered in myelin sheath divided by nodes of Ranvier
• electrical transmission - positive charge leads to action potential
• synapse - terminal buttons at synapse, presynaptic vesicles release neurotransmitter
• neurotransmitters - postsynaptic receptor site receives neurotransmitters from dendrites of adjoining neuron. specialist functions e.g. acetylcholine for muscle contraction
• excitation, inhibition and summation - adrenaline is excitatory, serotonin is inhibitory. postsynaptic neuron triggered if sum of excitatory and inhibitory signals reaches threshold
• psychotherapeutic drugs - SSRIs increase serotonin acitivity
• localisation and lateralisation - some functions localised (e.g. vision) or localised and lateralised (e.g. language)
• left and right hemispheres - language areas in LH (for most people). LH is the analyser, RH is the synthesiser. motor areas are contralateral. visual areas are contralateral and ipsilateral, LVF of both eyes to RH and RVF to LH. same of auditory areas
• evaluate hemispheric lateralisation

  • lateralisation in the normal brain
  • one brain
  • lateralisation vs plasticity
• lateralisation in the normal brain - global elements processed by RHand finer detail by LH (Fink et al)
• one brain - certain hemispheres dedicated to certain tasks but no dominant RH or LH (Nielsen et al)
• lateralisation vs plasticity - lateralisation enables multitasking e.g chickens (Rogers et al) but plasticity allows recovery of lost lateralised functions (Holland et al)
• brain plasticity - research suggests that neural connections can change or new connections can be formed
• research into plasticity - hippocampus in taxi drivers changes the structure after learning The Knowledge (Maguire et al). changes in hippocampus and the parietal cortex before and after exams (Draganski et al)
• evaluate plasticity

  • negative plasticity
  • age and plasticity
  • seasonal brain changes
• negative plasticity - drug use may cause neural changes (Medina et al). phantom limb syndrome due to reorganisation in somatosensory cortex (Ramachandran and Hirstein)
• age and plasticity - plasticity reduced with age, though Bezzola et al showed how golf training caused neural changes in over-40s
• seasonal brain changes - Songbirds' SCN shrinks in spring and expands in autumn (Tramontin and Brenowitz)
• procedure - eleven participants, split-brain operation for epilepsy (deconnect hemisphere)
• findings

  • objects shown to RVF (LH), person describe object, shown to LVF (RH), says 'nothing there'
  • object show to LVF (RH) - cannot name but can select item with left hand
  • pinup picture to LVF - participant giggles but reports nothing
• conclusions - lateralised brain, LH verbal and RH 'silent' but emotional
• evaluate split brain research

  • research support
  • generalisation issues
  • ethics
• research support for split brain research - split brain participants faster at some LH tasks (Luck et al), normally slowed down by inferior RH (Kingstone et al)
• generalisation issues - epilepsy is a confounding variable when comparing participants to 'normal' controls
• ethics - operation not done for the study and participants gave informed consent, but may not have fully understood and participation was stressful
• after brain trauma - healthy brain areas take over lost functions after trauma, happens quickly