Biopsychology

structure of the nervous system

central nervous system

• brain

• spinal cord

coordinator of everything

receives information from the environment

processes, makes decisions and makes these actually happen

• brain: decision maker

• spinal cord: major connection to the peripheral. does reflex actions

peripheral nervous system

millions of neurons transmit messages to and from the CNS

then subdivided into the autonomic and the somatic

somatic nervous system

voluntary, conscious, deliberate actions

muscle coordination and info from sensory receptors

autonomic nervous system

involuntary, unconscious actions

e.g. breathing, HR, digestion

sympathetic and parasympathetic (antagonistic pair)

sympathetic

gut: slows digestion

salivary glands: inhibits production

heart: increases rate

eye: dilates pupil

lungs: dilates bronchi

parasympathetic

increases digestion

increases saliva

decreases HR

constricts pupil

constrict bronchi

flight or fight response

1. the hypothalamus identifies a threat and instructs the sympathetic system to act.

2. stress hormone adrenaline is released from the adrenal glands into the blood stream

3. adrenaline prompts a number of physical changes in the body to prepare for fight or flight

4. following the fight or flight response the parasympathetic nervous system is activated to return the body back to a normal resting rate e.g. slows HR, breathing rate, reduces blood pressure

evaluating the fight or flight response

useful in evolutionary terms. when we need energy to deal with the situation it prepares us to have the energy to run away or stay and fight.

→ not useful for stressers that do not require physical activity e.g. modern ones like debt. these bodily changes can be unhelpful and lead to illness.

research in this area of flight and fight is gender biased (alpha- androcentric). the research is only done on male Ps then generalised to females as well. females are more likely to show tend and befriend response. produces less adrenaline so gather together and support more. 

the endocrine system (glands and their use)

• pituitary

• thyroid

• adrenal

• ovaries

works alongside the nervous system to control glands which release hormones into the bloodstream.

→ pituitary (base of brain under hypothalamus)

• stimulated other endocrine glands e.g. controls growth, blood pressure, water levels

• oxytocin (childbirth and breastfeeding), vasopressin (balances salt and water)

- thyroid (front of neck)

• controls speed of metabolism,breathing, temperature, brain development

• thyroxine

- adrenal (top of kidneys)

• regulates metabolism, blood pressure, development of sexual characteristics

• cortisol: controls body’s use of fats, proteins, carbs and the blood pressure

• adrenaline: flight or fight- increases HR etc

- ovaries (either side of uterus)

• produces and stores eggs

• oestrogen- breasts, wide hips, thickens uterine lining

• progesterone- thickens uterine linings, breasts to produce milk

types of neurons

sensory: carries messages from PNS to CNS. long dendrites and short axons.

relay: connect sensory to motor (or other relay). short dendrites and short axons

motor: connect CNS to affects like muscles and glands. short dendrites and long axons

structure of a neuron

cell body with nucleus that contains genetic material

dendrites → axon → terminal buttons

myelin sheath protects and speeds up impulse. has nodes of ranvier to force it to ‘jump’

reflex arc 

uses relay neurons in spinal cord to produce automatic response to environmental issues which need a quick response e.g. moving hand from heat

1. detected by sense organs in PNS which convey message along sensory neuron

2. message researches CNS → relay neuron → motor neuron

3. then carries messages to effectors such as a muscle

electrical transmission (done within neurons)

in a resting state the inside of the neuron is negatively charged compared to the outside

when activated by a stimulus, the inside becomes positively charged for a split second causing an action potential to occur creating an electrical impulse

this travels down the axon towards the end of the neuron (and triggers the release of neurotransmitters)

chemical transmission (done between neurons)

each neuron is separated from the next by a tiny gap called a synapse

signals between neurons are transmitted chemically

• neurotransmitters are released from tiny sacs called synaptic vesicles.

• they mostly diffuse across the synapse to the next neuron

• (or are broken down by enzymes or reabsorbed into vesicles)

• once a neurotransmitter crosses the gap it is taken up by the receptor sites and converted back into electrical impulses.

• each neurotransmitter has its own specific molecular structure that fits to receptor site (lock and key)

  

excitation

neurotransmitter increases the positive charge of the post synaptic neuron which increases the likelihood that the post synaptic neuron will pass on the electrical impulse e.g. adrenaline

inhibition

neurotransmitter increases the negative charge of the post synaptic neuron which decreases the likelihood that the post synaptic neuron will pass on the electrical impulse e.g. serotonin

summation

whether a postsynaptic neuron fires

• sum of excitatory and inhibitory influences

• net effect either excitatory or inhibitory

Localisation

Lateralisation

3 concentric layers

• central core

• limbic system

• cerebrum (split into 4 lobes)

temporal lobe

• auditory

Occipital lobe

• visual

Parietal lobe

• somatosensory

Frontal lobe

• Motor

Language centres

• Broca’s

• Wernicke’s

Evaluating localisation of the brain

evidence from neurosurgery- damage to areas of brain linked to mental disorders

• neurosurgery treats mental disorders by targeting specific areas of the brain that may be involved.

• DOUGHERTY: 44 people who had had cingulotomy (isolate cingulate gyrus involved in OCD) after 32 weeks: 30% had successful response, 14% partial response

• behaviours in mental disorders are localised.

evidence from brain scans. 

• PETERSON: used brain scans to demonstrate how Wernicke’s area was active during listening task and Broca’s during a reading task. 

• BRACKNER + PETERSON: semantic and episodic memories reside in different parts of the prefrontal cortex. 

• confirms localised areas for everyday behaviours. 

→ LASHLEY: removed areas of cortex (10%-50%) in rats learning route through maze. no area was proven to be more important than any other area in terms of rat’s ability to learn the route. more about the process of learning and needing more of the cortex. more holistic as emphasises involvement of the whole brain. 

When the brain has been damaged and a function has been impacted the rest of the brain helps to recover it. Law of equipotentiality- surviving brain circuits chip in so the same function can be achieved e.g. stroke victim’s recovery- learning relies on the whole brain. 

Language not just localised to Broca’s and Wernicke’s area

• only 2% of researchers believe it is completely controlled by these areas.

• advances in brain imaging e.g, fMRI means neural processes can be studied with more clarity.

• language function distributed more holistically in brain e.g. language streams across cortex- brain regions in right hemisphere, thalamus. 

• holistic so contradicts localisation