BIOPSYCH

• Nervous system


  2 main functions:

  * collect, process and respond to info in environment

  * coordinate working of different organs and cells in body
• Nervous system: component CNS

  Central nervous system

  Made up of brain and spinal cord

  Brain = centre of all conscious awareness

  Outer layer of brain = cerebral cortex - highly developed in humans is what distinguishes higher mental functions

  Spinal cord extension of brain - responsible for reflex actions - passes msgs to + from brain and connects nerves to PNS
• Nervous system: component PNS

  Peripheral nervous system

  Transmits msgs via neurons to + from nervous system

  Sub-divided into autonomic nervous system (ANS) - governs vital functions e.g: breathing, heart rate +

  somatic nervous system(SNS) - controls muscle movements + receives info from sensory receptors
• Endocrine system


  Works alongside NS to control vital functions through action of hormones

  More slower than NS

  Powerful effects and widespread
• Endocrine system: Glands

  Produce hormones

  Major = pituitary gland , located in brain , controls release of hormones from other glands
• Endocrine system: hormones

  Secreted in bloodstream + affects any cell in body that has receptor for hormone
• Endocrine system: FIGHT or FLIGHT

  Endocrine system + ANS work together during stressful events

  1).stressor perceived, hypothalamus triggers activity in sympathetic branch of ANS - normal resting state ( parasympathetic ) to sympathetic state

  2). Stress hormones adrenaline released from adrenal medulla into bloodstream

  3). Adrenaline triggers physiological changes e.g: increased HR, BR, dilate pupils, inhibit saliva production (FIGHT OR FLIGHT RESPONSE)

  4). Threat passed parasympathetic NS returns body to resting state - reduces physiological changes E.g: decrease HR + BR, stimulate saliva
• Neurons


  Loads in brain

  Provide NS with primary means of communication by transmitting signals electrically and chemically

  3 types

  
• Neurons types


  * Motor - connect CNS to effectors ( muscle, glands) have short dendrites + long axons

  * Sensory - carry msgs from PNS to CNS have long dendrites + short axons

  *Relay - connect sensory to motor have short dendrites + short axons
• Structure of neurons

  * Cell body (soma) =nucleus

  * Dendrites =branch, carry nerve impulses from other neurons towards cell body

  * Axon = carries electrical impulses away from cell body down length of neuron, covered in fatty layer of myelin sheath - protects axon, gaps in axon = nodes of ranvier - speed up transmission of impulse

  * Terminal buttons at end of axon = communicate with next neuron across synapes
• Neurons: Electric transmission

  Neuron in resting state = inside cell negatively charged compared to outside

  Neuron activated inside cell = positively charged which causes action potential to occur

  Creates electrical impulse that travels down axon towards end of neuron
• Synaptic transmission : Synapse


  gap between neurons
• Synaptic transmission

  Electrical impulse reaches pre-synaptic terminal triggering release of neurotransmitters from synaptic vesicles into synapse

  Diffuses across to receptor sites on postsynaptic terminal
• Synaptic transmission: neurotransmitters

  Chemicals

  Each has own specific molecular structure that binds to complementary receptor site
• Synaptic transmission: excitation and inhibition

  Excitatory neurotransmitters (e.g. adrenaline)

  make the post-synaptic cell more likely to fire, whereas inhibitory neurotransmitters

  (e.g. serotonin) make them less likely to fire.
• Synaptic transmission: Summation

  Excitatory/inhibitory influences are summed

  Must reach certain threshold to trigger action potential of postsynaptic neuron
• Localisation of function : Holistic theory

  All parts of brain involved in processing thought + action

  Later = specific area of brain linked with specific physical + psychological functions
• Localisation of function : Brain divided + lateralisation

  2 halves = left + right hemisphere

  lateralisation = physical + psychological functions controlled by particular hemisphere

  Left side of body controlled by right hemisphere , right side of body controlled by left hemisphere
• Localisation of function : Outer layer of brain

  Cerebral cortex

  Separates humans from animals as is highly developed

  Grey due to location of body cells = grey matter
• Localisation of function : Lobes

  * Motor area = frontal lobe , responsible for

  voluntary movements , if damaged = loss of control of movement

  * Somatosensory area = parietal lobe , receives incoming sensory

  information from the skin

  * Visual area = occipital lobe - right visual field to left visual cortex , left visual field to right visual cortex

  * Auditory area = temporal lobe - responsible for analysing speech-based info , damage = hearing loss

  
• Localisation of function : Broca's area


  Speech production

  Left frontal lobe

  Damage = Broca's aphasia - slow speech + lack fluency
• Localisation of function : Wernicke's area


  Language comprehension

  Left temporal lobe

  Damage = wernicke's aphasia - cant understand language - nonsense words
• Brain plasticity

  Infancy = brain experiences rapid growth in synaptic connections

  As age rarely used connections are deleted , frequently used ones are strengthened = synaptic pruning
• Brain plasticity: Maguire - taxi drivers


  Found more volume of grey matter in hippocampus in london taxi drivers than control group - part of brain linked with development of spatial + navigational skills

  Longer been in job = bigger hippocampus - know all streest and routes
• Brain plasticity: Draganski


  Imaged brains of medial students 3 months before + after final exams

  Learning-induced changes seen in hippocampus + parietal cortex as a result of exam
• Functional recovery of brain after trauma

  Important example on neural plasticity

  Healthy brain takes over functions of damaged areas

  Spontaneous recovery - happens quickly after trauma

  Brain rewires + reorganise self by forming new synaptic connections close to damaged areas

  Secondary neural pathways are activated to enable functioning to continue
• Functional recovery of brain after trauma: Structural changes in brain


  * Axonal sprouting = growth of new nerve endings which connect with other undamaged cells to form new neuronal pathways

  * Reformation of blood vessels

  * Recruitment of similar areas on opposite side of brain to perform specific tasks
• Split-brain research into hemispheric lateralisation: Sperry


  Demonstrate that hemispheres were specialised for certain functions + could perform tasks independently of 1 another

  Studied grouop of epileptics who had a commissurotomy ( cut out corpus callosum - Connects hemispheres )
• Split-brain research into hemispheric lateralisation: Sperry procedure

  Image/word presented to RVF and LVF

  Hemispheres dont share info as corpus callosum cut out

  Had 3 different experiments
• Split-brain research into hemispheric lateralisation: Sperry procedure DESCRIBING TASKS


  RVF - drawn what was seen

  LVF - cant see anything as Right hemisphere lack language centres and cant receive from LH as CC cut
• Split-brain research into hemispheric lateralisation: Sperry procedure RECOGNITION BY TOUCH


  LVF - coudnt name but could select matching object using left hand

  Couldnt verbally identify what saw but could understand
• Split-brain research into hemispheric lateralisation: Sperry procedure MATCHING FACES


  2 words presented on either side of VF

  LVF - writes words with left hand

  RVF - says word

  
  

  Composite words made up of 2 diff halves of a face

  LH - verbal description

  RH - selection of matching pic
• Ways of studying brain

  Techniques used for diagnosing illness

  Investigate localisation
• Ways of studying brain: FMRI

  Functional magnetic resonance imaging

  Detects changes in blood oxygenation + flow that occur due to neural activity in specific brain areas

  Brain more active = need more O2 and blood flow directed to active area

  Produce 3D image showing which part active
• Ways of studying brain: FMRI ;)

  Non-invasive

  Dont use radiation like other techniques (PET scans) so is safe

  Also produce image with high spatial resolution - can provide clear pic of brain activity
• Ways of studying brain: FMRI :(

  Expensive compared to other techniques

  Poor temporal resolution due to 5 sec time lag between initial neural activity + image = not truly representative
• Ways of studying brain: EEG

  Electoencephalogram

  Measure electrical activity in brain via electrodes using skull cap

  Scan recording represents brainwave patterns generated from millions of neurons

  Used as diagnostic tool - can indicate abnormalities
• Ways of studying brain: EEG :)

  Invaluable in diagnosing conditions like epilepsy

  Also contributed in understanding stages of sleep

  Has extremely high temporal resolution
• Ways of studying brain: EEG :(

  Info received from millions of neurons so produces generalised signal - dont know exact source of activity
• Ways of studying brain: ERPs

  Event-related potentials

  what is left when all extraneous brain activity from EEG recording is filtered out

  Done using Statistical technique leaving only responses that relate to specific stimulus

  ERPS = type of brainwave triggered by particular events , many diff forms