biopsychology

• what is the nervous system?

  a complex system if nerve cells that carry messages to and from the brain and spinal cord to different parts of the body and helps all parts of the body communicate with each other
• what are the two sub systems of the nervous system?

  central nervous system (CNS) and peripheral nervous system (PNS)
• central nervous system

  made up of brain and spinal cord

  brain - centre of all conscious awareness - divided into 2 hemispheres

  spinal cord - responsible for reflex actions and relaying info between brain and rest of body
• peripheral nervous system

  transmits messages via neurons to and from central nervous system

  function is to relay nerve impulses from the CNS to the rest of the body and vice versa

  sub divided into:

  somatic nervous system - controls voluntary actions - carries sensory and motor information to and from CNS

  autonomic nervous system - controls involuntary actions like breathing and digestion - carries only motor information to and from CNS
• what are the two systems of the autonomic nervous system?

  Sympathetic and parasympathetic

  sympathetic - involved in emergency like fight or flight - causes the body to release stored energy, pupils to dilate, hair to stand on end - slows down less important bodily processes such as urination and digestion

  parasympathetic - involved in returning the body to a rest state once emergency has passed e.g slow heartbeat
• structure of a neuron

  vary in size from less than a millimetre to up to a metre long

  cell body includes a nucleus - has branch like structures called dendrites which receive signals from other neurons

  axon carries impulses away from cell body down the neuron - covered in myelin sheath that protects it - myelin sheath has gaps called nodes of ranvier which speed up transmission of impulses

  axon terminal at end of axon that communicate across the synapse
• what are three main types of neuron

  sensory, relay and motor
• what is the sensory neuron?

  Sensory neuron: neuron that transmits sensory information from the body to the central nervous system

  long dendrites and short axons
• what is the relay neuron?

  connect sensory neurons to motor neurons and other relay neurons

  carry messages from one part of CNS to another

  allow sensory and motor neurons to communicate

  short dendrites and short axons
• what are motor neurons?

  carry messages from the CNS to directly or indirectly control muscles

  release neurotransmitters when stimulated that bind to receptors on muscle and triggers a response - leads to muscle movement

  short dendrites and long axons
• what is the process of synaptic transmission?

  action potential travels down axon of presynaptic neuron to axon terminal

  stimulates vesicles to fuse with membrane of presynaptic neuron and release neurotransmitters into synapse

  neurotransmitters can bind to receptors on dendrites of post synaptic neuron or be reuptaken to the presynaptic neuron vesicles, can also be engulfed by enzymes
• what is excitation?

  e.g adrenaline

  increases positive charge of the neuron making it more likely to fire
• what is inhibition?

  e.g serotonin

  causes neuron to be more negatively charged and less likely to fire
• what is summation?

  neuron receives both excitatory and inhibitory neurotransmitters at same time

  add up excitatory and inhibitory synaptic input

  if net effect = inhibitory then less likely to fire

  if net effect = excitatory then more likely to fire
• endocrine system

  a chemical system of communication that instructs glands to release hormones directly into the bloodstream - hormones carried towards target organs and regulate bodily functions

  glands - organs in the body that produce and secrete hormones to regulate bodily functions e.g pituitary gland

  hormones - chemicals that circulate in the bloodstream and influence target organs to regulate bodily activity e.g adrenaline
• what are the 5 examples of glands/hormones?

  1. Pituitary gland - master gland - influences release of hormones from other glands
  2. 2. adrenal gland - produces adrenaline for fight or flight
  3. 3. pineal gland - produces melatonin for sleep
  4. 4. testes - produces testosterone
  5. 5. Ovaries - produces oestrogen/progesterone
• fight or flight response

  acute stressor (e.g sudden fright) - hypothalamus directs sympathetic nervous system - send neurotransmitters to the adrenal gland - releases adrenaline - causes fight or flight response - triggers physiological reactions e.g increased heart and breathing rate, dilated pupils, inhibited digestion
• what is the memory aid for the stages of fight or flight?

  Aliens - acute stressor

  Have - hypothalamus

  Somehow - sympathetic

  Always - adrenal gland

  Adored - adrenaline

  Foam - fight or flight

  Parties - physiological reactions
• hemispheric lateralisation

  the idea that the two hemispheres of the brain are functionally different and that certain mental processes are mainly controlled by one hemisphere rather than the other

  the two hemispheres are bridged by the corpus callosum which acts as a communication pathway so the two hemispheres can exchange information
• what does it mean that the brain is contralateral?

  some parts of the left hemisphere deal with the right side of the body and the right hemisphere deals with the left side of the body

  e.g if a person has a stroke in the motor areas of the right hemisphere, the left side of the body will be affected
• what are the functions of the left hemisphere?

  language processing and speech production e.g broca's area and wernicke's area

  logical tasks and problem solving
• what are the functions of the right hemisphere?

  recognising emotions and spatial relationships
• localisation of function

  specific functions have specific locations in the brain
• what are the six parts of the brain?

  motor cortex, somato-sensory cortex, visual cortex, wernicke's area, auditory centre and broca's area
• what is the function of the motor cortex?

  controls fine motor movements e.g writing

  found in rear of frontal lobe

  damage = loss of control over motor movements
• what is the function of the somato-sensory cortex?

  sensory perception like touch e.g heat

  damage = can't feel hot/cold or pain|

  found at front of parietal lobe
• what is the function of the visual cortex?

  visual perception

  the right visual field goes to the left hemisphere and the left visual field goes to the right hemisphere

  damage = blindness

  found in the occipital lobe of both hemispheres
• what is the function of wernicke's area?

  language comprehension and understanding

  damage = muddled sentences, neologisms, unable to find the right words

  found in temporal lobe of left hemisphere
• what is the function of the auditory centre?

  auditory information

  damage = hearing loss

  found in temporal lobe of both hemispheres
• what is the function of broca's area?

  speech production

  damage = slow, laborious speech (broca's aphasia)

  found in frontal lobe of left hemisphere
• evaluation of localisation of function pt1

  + support from case studies of brain damaged patients - damage to broca's area led to broca's aphasia (difficulty producing speech) - e.g tan (only word he could say) - supports the idea

  + support from brain scan research - using brain scans to show how wernickes area was active during a listening task and broca's during a reading task - supports the idea

  -criticism from animal research - removed between 10-50% of the cortex in rats that were learning a maze - found no area was more important for learning the maze - suggests learning is too complex
• evaluation of localisation of function pt 2

  -brain functioning more complex than localisation suggests - some research suggested the way brain areas communicate might be more important - studied one brain damaged patient who lost ability to read & suffered damage to connection between visual cortex & wernickes area - shows complex communication between areas makes brain functioning complex

  -criticism from plasticity - brain can reorganise itself to recover lost functions - stroke victims recover abilities that were lost - theory too simplistic
• sperry's split brain research

  ppts all had split brain surgery - cutting the corpus collosum - controls severe epileptic seizures

  asked them to focus on a dot in centre of screen - projected image or word to their right or left visual field followed by a task (describe what you see or pick up object)

  findings:

  object shown to right visual field - could describe what was seen - shown to left - could not describe "i see nothing" - language processed in left however could pick up matching object using their left hand - could not verbally identify what was seen but can select the object
• evaluation of sperry's split brain research pt 1

  +well controlled - used highly standardised procedures in a controlled environment - e.g one eye covered, info flashed for one tenth of a second prevent info spreading to both sides of brain - high internal validity

  -flawed - unusual and limited sample, not well matched to control group - only 11 split brain patients, all received drug therapies for different amounts of time, some may experienced more disconnection than others - doubt the conclusions
• evaluation of sperry's split brain research pt 2

  -differences in functions may be overstated - led to belief that there are clear-cut distinctions between the hemispheres - however distinction much messier than this as there is constant communication, both sides can perform functions when required - process is more complex

  -case studies show language may not be restricted to left - case of JW who developed ability to speak from right hemisphere - can speak about info on both sides of brain - disconfirms that right can't control language
• evaluation of sperry's split brain research pt 3

  -lateralisation complicated by age - lateralisation of function may change through lifetime - language became more lateralised before age 25, after 25 lateralisation decreased with each decade of life - suggests it is a more complex process
• plasticity

  the brains ability to change and adapt as a result of experience and new learning

  during infancy brain has a rapid growth of number of connections - peak at approx 15,000 at age 2-3

  as we age, rarely used connections are deleted and frequently used connections are strengthened - called synaptic pruning

  plasticity not restricted to a critical period during childhood - can occur at any stage of life
• functional recovery of the brain

  following damage to the brain, unaffected areas are able to adapt and compensate for the damaged areas - neural plasticity

  healthy areas of the brain may take over the functions of the damaged areas

  this can occur quickly (spontaneous recovery) and then slow down

  can also form new synaptic connections close to the damaged areas

  secondary neural pathways are activated to enable functioning to continue

  axonal sprouting - the growth of new nerve endings which connect with other nerve cells to form new neuronal pathways
• factors affecting the recovery of the brain

  age - after brain trauma patients 40+ regained less function than younger patients

  gender - women recover better from brain injury as their function is not lateralised - 325 patients examined - women performed significantly better than men on tests of attention and language - men outperformed women in visual analytic skills
• evaluation of plasticity pt 1

  +support from human research - MRI scans of brains of london taxi drivers - found more volume of grey matter in posterior hippocampus than control group - supports the idea that brain can adapt

  +support from animal studies - rats in complex environments had increased number of new neurons in hippocampus than rats in simple cages - supports the idea that brain can adapt - however no extrapolation

  -contributed to neurorehabilitation - physical therapy may be required when spontaneous recovery slows down e.g movement therapy - helps improve patients lives