Biopsychology

• The central nervous system (CNS):

  • made up of brain and spinal cord
  • brain function: centre of all conscious awareness
  • Spinal cord function: relay info from brain to rest of the body. Allows brain to monitor and regulate bodily processes and controls voluntary movement
  • to do this, brain must be able to receive info from sensory receptors and send messages to muscles and gland - done via spinal cord
• The peripheral nervous system (PNS)

  • all neurones outside CNS make up PNS
  • Function: relay nerve impulses from CNS to rest of the body and back to CNS
  • PNS is subdivided into somatic and autonomic nervous system
• Somatic nervous system (SNS)

  • made of sensory and motor neurones
  • controls Voluntary muscle movement
  • Also involved in reflex actions
  • Transmits sensory information to CNS
• autonomic nervous system (ANS)

  • made of motor neurones only
  • controls involuntary body functions
  • can be further divided into sympathetic and parasympathetic nervous system
• motor neurones

  • short dendrites and long axons
  • Located in CNS and project their axons outside CNS to directly or indirectly control muscles
  • Sends messages via long axons from brain to muscles or effectors
  • When axons fire, the muscles with which it forms synapses with contracts. When the neuron is inhibited the muscle relaxes
  • They form synapses with muscles and controls their contractions. When stimulated they bind to receptors on muscle and trigger a response which leads to muscle movement

  
• Sensory neurones

  • long dendrites and short axons
  • Convert info from sensory receptors into neural impulses
  • Carry messages from sensory receptors via PNS to CNS
  • Not all sensory info travels as far as the brain, some neurones terminate in the spinal cord. This allows reflex actions to occur quickly without delay of sending impulses to brain

  
• Relay neurones

  • short dendrites and short axons
  • Connects with other neurones e.g allow sensory and motor neurones to communicate with each other
  • Found in CNS only
  • When Impulse reaches the brain, they translate into sensations, so organism can decide how to respond appropriately

  
• draw and label synaptic transmission

  ..

  
• process of synaptic transmission:

  1. action potential reaches pre-synaptic terminal and triggers vesicles to release neurotransmitters into synaptic cleft
  2. neurotransmitters diffuse across synaptic cleft to post synaptic neurone and bind to post synaptic receptor sites on post synaptic membrane
  3. stimulation of post-synaptic receptors converts chemical message back to electrical impulses and synaptic transmission happens again
  4. the effects are terminated by reuptake. neurotransmitters are taken up by pre-synaptic neurone where they are again stored in vesicles ready for later release
• excitatory and inhibitory neurotransmitters

  • excitatory neurotransmitters e.g adrenaline and noradrenaline
  • inhibitory neurotransmitters e.g serotonin and GABA
  • if neurotransmitter is excitatory, this causes excitation of post synaptic membrane, making post synaptic neurone more likely to fire an electrical impulse
  • if neurotransmitter is inhibitory , this causes inhibition of post synaptic membrane, making post synaptic neurone less likely to fire
  • excitatory and inhibitory influences are summed (summation): if net effect is excitatory (more likely to fire), inhibitory (less likely to fire)
• the endocrine system:

  • a network of glands that manufacture and secrete hormones
  • hormones - chemical messengers that regulate bodily functions
  • endocrine system works closely with nervous system to regulate physiological processes
  • endocrine system is much slower than nervous system but has widespread effects, as endocrine system uses blood vessels to transmit hormones to target cells, than nerves to transmit impulses
  • endocrine system is regulated by feedback - results in stable concentrations of hormones circulating in bloodstream
• ovaries

  • hormones: oestrogen and progesterone
  • production of eggs and female sex hormones
  • female reproductive function
  • associated with increased sensitivity to social cues (important in pregnancy)
• pituitary gland

  • hormones: ACTH, LH, FSH and oxytocin
  • master gland that regulates many of the body's function
  • produces hormones that control the release of hormones from other glands
  • oxytocin - when released it stimulates contraction of womb in childbirth and important for mother-infant bonding
  • FSH - in females, stimulates ovaries to produce oestrogen and progesterone. In males, stimulates testes to produce testosterone
  • ACTH - when released in response to stress, it stimulates adrenal gland to release cortisol
• testes

  • hormone: testosterone
  • produces sperm and male sex hormones
  • development of male characteristics e.g deepening of voice, facial hair, growth spurt
  • important for sex drive, sperm production and muscle strength and associated with general health and wellbeing in men
• adrenal gland

  • hormones: cortisol, adrenaline, noradrenaline
  • causes physiological changes associated with arousal and prepares body for fight or flight
  • supports bodily functions such as cardiovascular and anti-inflammatory functions
  • adrenaline - helps body respond to stressful situations e.g increased heart rate
  • cortisol - released in response to stress. Affects glucose metabolism, lowers sensitivity to pain and suppresses immune system
• The fight or flight response:

  • theory that states the body produces a range of physiological responses when the body faces a perceived threat
  • amygdala first detects threat and then signals hypothalamus to activate SNS
  • body goes from normal resting parasympathetic state to physiologically aroused sympathetic state - part of peripheral nervous system
  • the nervous system and endocrine system work together
  • SNS then sends signal to adrenal medulla to release adrenaline -produces physiological responses
  • body is returned to parasympathetic state after stressor has passed - maintain homeostasis
• what are the physiological responses produced by adrenaline in the fight or flight response?

  • increase blood/oxygen to skeletal muscles and brain to prepare body for action
  • increases heart rate
  • constricts blood vessels - raises blood pressure
  • non-emergency bodily functions are suppressed e.g digestion
  • after stressor has passed, activities increased by adrenaline would be reduced
  • rest and digest is activated
• AO3 Fight or flight - weakness 1

  • physiological responses are more adaptive for stress response that requires energy (e.g fleeing a lion)
  • modern life stressors don't require physical activity (e.g exam stress)
  • leads to repetitive stress responses -> fatal health issues e.g cardiovascular disease
  • constant constriction of blood vessels -> increases blood pressure -> damaged blood vessels -> cardiovascular disease
  • body can't tell the difference between modern stressors and the stressors that come up in the evolutionary past
• AO3 Fight or flight - weakness 2

  • limited explanation
  • suggested that the first phase of reaction to threat is not fight or flight, but instead to avoid confrontation
  • before responding with attacking or running away, most animals (including humans) display a 'freeze' response
  • this is a 'stop, look and listen' response - animal is hyper-vigilant
  • more adaptive for humans - focuses attention and makes them look for new information to produce the best response for that threat
• AO3 Fight or flight - weakness 3

  • male bias in psychology
  • men and women had different societal roles during evolutionary past
  • men = hunters, so fight or flight is appropriate
  • women = gatherers, so 'tend and befriend' response is more appropriate
  • tend to offspring and befriend other females to form protective alliances - fight or flight not appropriate
  • female primary role - protect themselves and their young
  • completely different coping mechanism to stress
  • studies show women release oxytocin during stress - suppresses fight or flight
• AO3 Fight or flight - weakness 4

  • research evidence - Speisman et al
  • asked students to watch gruesome medical videos of initial rites and genital mutation and monitored their heart rates simultaneously
  • some pts told that the procedures were voluntary and joyful rites and others told it was traumatic
  • heart rates in first group increased whilst in second group it decreased
  • humans aren't purely reactive to stressors like theory assumes
  • we actively engage with stressors, using cognitive and emotional strategies
  • humans have more complex, dynamic stress responses that go beyond fight or flight
• what does localisation of brain function mean?

  • different areas of the brain are responsible for different behaviours and cognitive processes and are associated with different parts of the body
  • some functions are more localised than others
  • if certain areas are damaged, then the function associated with that part of the brain would also be affected
  • before this, scientists supported the holistic theory of the brain - that all parts of the brain are involved in processing thought and action
• label the lobes of the brain

  1 - temporal lobe

  2 - occipital lobe

  3 - parietal lobe

  4 - frontal lobe

  
• parietal lobe

  • knowing right from left
  • body orientation
  • sensations
• occipital lobe

  • vision
  • colour perception
• cerebellum

  • balance
  • coordination and control of voluntary movement
  • fine muscle control
• temporal lobe

  • understanding language
  • memory
  • behaviour
  • hearing
• frontal lobe

  • problem solving
  • speaking
  • voluntary motor activity
• motor cortex

  • located in frontal lobe, across pre-central gyrus
  • responsible for voluntary motor movements
  • both hemispheres have motor cortex
  • damage to this area can result in loss of fine movements
• somatosensory cortex

  • located in parietal lobe, along post-central gyrus
  • responsible for processing input from sensory receptors
  • produces sensations of touch, pressure, pain and temperature, which it then localises to specific body functions
• visual cortex

  • located in occipital lobe
  • receives and processes visual info
  • but visual processing begins in the retina where light hits photoreceptors
  • action potentials are produced and transmitted to optic nerve
  • visual cortex spans both hemispheres
• auditory cortex

  • found in temporal lobes on both hemispheres
  • responsible for the analysis of speech-based information e.g hearing
  • auditory processing begins in cochlea, where sound waves are converted to action potentials that travel along the auditory nerve to the auditory cortex
• Language centre - Broca's area

  • language centres are lateralised to the left hemisphere
  • responsible for speech production
  • located in left frontal lobe
  • Broca's aphasia - damage to broca's area
  • can only talk in short, meaningful sentences
  • speech lacks fluency
• Language centre - Wernicke's area

  • language centres are lateralised to the left hemisphere
  • responsible for the comprehension of language
  • located in left temporal lobe
  • wernicke's aphasia - damage to wernicke's area
  • they could speak but unable to understand language, such that the speech they produced were fluent but meaningless
• AO3 Localisation of brain function - Strength 1

  • Phineas Gage case study
  • american rail road worker aged 25
  • preparing rail roads using explosives
  • powder detonated unexpectedly and a 43 inch iron rod fired into his head, passing left cheek, left eye and out of his skull
  • damage to frontal lobe impacted personality - calm reserved person -> social impairment
  • proves different areas of brain associated with different functions
  • validity of theory
  • but case study cant be generalised
  • might lack internal validity - other factors could have influenced changes in behaviour
• AO3 Localisation of brain function - strength 2

  • studies show those with Broca's aphasia and Wernicke's aphasia result in impaired speech production and speech comprehension, respectively
  • Broca's aphasia = damage to Broca's area
  • 'Tan' case study - Broca studied a patient that could only say the syllable 'Tan' but had no issue in understanding language
  • post Tan's death, Broca found damage to left frontal lobe
  • Wernicke studied patients that could produce fluent but meaningless speech
  • supports that damage to these areas resulted in corresponding impacted functions
• AO3 Localisation of brain function - weakness 1

  • brain has plasticity - the ability of the brain to reorganise itself to recover lost function when it's been damaged
  • doesn't happen all the time but there are plenty of cases of stroke victims that recovered those abilities that were lost as a result of illness
  • Danelli et al case study - a boy who had his left hemisphere removed at age 2 due to a tumour
  • under strict localisation theory, this should have permanently impacted his language ability
  • regained normal language abilities - right hemisphere took over
  • Undermining evidence
• AO3 Localisation of brain function - weakness 2

  • French neurologist found that the loss of ability to read resulted from damage to connection between wernicke’s and visual cortex 
  • Suggests loss of ability to read is due to wernicke's (comprehension) and visual cortex (processes visual information)
  • Localisation theory states it’s only due to wernickes 
  • Reduces validity
• what does lateralisation of the brain mean?

  • idea that the 2 halves of the brain are functionally different and certain mental processes and behaviours are mainly specialised to one hemisphere rather than the other
  • e.g language centres localised to broca's area and wernicke's area and lateralised to the left hemisphere
• the corpus callosum

  • the 2 hemispheres don't work in isolation
  • thick bundle of nerves that connects the 2 hemispheres
  • allows both sides to communicate and work as a complete organ
  • the 2 hemispheres retain their own roles while working together