Biopsychology

what are the key assumptions of the nervous system?

there is a genetic basis for behaviour - how differences in chromosomal makeup affects behaviour

assumes behaviour and experiences are caused by activity in the nervous system

what is the structure of the human nervous system?

what is the central nervous system (CNS)?

made up of the brain and spinal cord

two main functions:

1. control of physical movement

2. regulation of homeostatic function

the brain receives information via sense organs and sends messages to the body using nerve cells in the spine

what are the four main areas of the brain?

cerebrum

cerebellum

brain stem

diencephalon

what is the cerebrum?

largest part of the brain

divided into two cerebral hemispheres

what is the cerebellum?

beneath the back of the cerebrum

involved in controlling motor skills, balance and coordinating muscles to allow for precise movements

what is the brain stem?

regulates automatic functions - e.g. breathing

motor and sensory neurons travel through the brain stem - allows impulses to travel between the brain and spinal cord

what is the diencephalon?

beneath the cerebrum and on top of the brain stem

contains the thalamus and hypothalamus

the thalamus acts as a relay for incoming nerve impulses - directs them to the appropriate parts of the brain where they can be processes

the hypothalamus has functions like regulation of body temperature, hunger and thirst, and acts as a link between the endocrine system and nervous system

what is the spinal cord?

relays information between the brain and the rest of the body - allows the brain to monitor and regulate bodily processes and coordinate voluntary movements

spinal nerves connect to specific muscles and glands

contains circuits of nerve cells that enable simple reflexes without direct involvement from the brain

what is the peripheral nervous system (PNS)?

all nerves outside of the CNS

relays impulses from the CNS to the rest of the body and back

made up of the somatic and autonomic nervous systems

what is the somatic nervous system?

made up of 12 pairs of cranial nerves and 31 pairs of spinal nerves

somatic nerves have both sensory and motor neurons - sensory neurons relay messages to the CNS, motor neurons relay information from the CNS to other areas of the body

involved in reflex actions without the involvement of the CNS - allows reflexes to occur quickly

what is the autonomic nervous system (ANS)?

regulates involuntary actions - e.g. heartbeat, digestion

has two parts:

1. sympathetic nervous system

2. parasympathetic nervous system

both systems tend to regulate the same organs but have the opposite effects - due to the neurotransmitters associated with each system

sympathetic nervous systems generally use the neurotransmitter noradrenaline - it uses acetylcholine, which has inhibiting effects

what is the sympathetic nervous system?

involved in responses that help to deal with emergencies - fight or flight

neurons from the sympathetic nervous system travel to almost every organ and gland, preparing the body for rapid action

what is the parasympathetic nervous system?

relaxes the body after an emergency has passed

involved with energy conservation and digestion - called the rest and digest system

what are the opposing actions of the sympathetic and parasympathetic nervous systems?

what are neurons?

cells that conduct nerve impulses

what people think and feel are caused by electrochemical events occurring within and between neurons

three main types: sensory, relay, motor

what is the structure of neurons?

dendrites

axons

myelin sheath

synaptic terminal

what are dendrites?

receive signals from neurons or sensory receptor cells

typically connected to the cell body

what are axons?

long slender fibre that carries nerve impulses in the form of electrical signals - action potential

transmit away from the cell body towards the axon terminals

what are myelin sheaths?

all neurons except relay neurons are surrounded by myelin sheaths

insulates the axon so electrical impulses travel faster along the axon

what are synaptic terminals?

the axon connects the neurons using synaptic transmission

what are sensory neurons?

in receptor cells - e.g. eyes, ears, skin

carry nerve impulses from the PNS to CNS

when the nerve impulses reach the brain they are translated to ‘sensations’

not all sensory neurons reach the brain - some stop at the spinal cord

have long dendrites and short axons

what are relay neurons?

between sensory input and motor output/response

in the CNS

allow sensory and motor neurons to communicate

have short dendrites, long axons and no myelin sheath

what are motor neurons?

in the CNS

control muscle movements and carry messages from the CNS to muscles and glands

release neurotransmitters that bind to receptors muscles to trigger a response and cause movement

what is the reflex response?

in a reflex arc, a stimulus is detected by sense organs in the PNS, which conveys a message along a sensory neuron

the message reaches the CNS and connects to a relay neuron, and is then transferred to a motor neuron

it is then carries to an effector, which causes a muscle to contract

what is action potential?

when a neuron is not sending a signal it is ‘at rest’ - the inside of the neuron is negative relative to the outside

when a neuron is activated by a stimulus, the inside of the cell becomes positively charged - action potential

it creates the electrical impulses which travel through neurons

what are neurotransmitters?

chemicals that are released from a synaptic vesicle into the synapse by neurons

affects the transfer of an impulse to another nerve or muscle

‘taken back up’ into the terminal buttons of neurons - reuptake

can only travel in one direction at the synapse

how does synaptic transmission work?

1. information is passed to the axon in the form of an action potential

2. synaptic vesicles at the axon terminals contain neurotransmitters

3. when action potential reaches the vesicles, they release their neurotransmitters into the synapse

4. neurotransmitters carry the signal across the synaptic gap

5. bind to receptor sites on the postsynaptic neurons - become activated and produces excitatory or inhibitory effects on the postsynaptic neuron

what do excitatory neurotransmitters do?

e.g. noradrenaline

causes a positive electrical charge in the cell membrane - results in an excitatory postsynaptic potential (EPSP)

makes the postsynaptic cell more likely to fire

what do inhibitory neurotransmitters do?

e.g. GABA

results in an inhibitory postsynaptic potential (IPSP)

makes the postsynaptic cell less likely to fire

what is the endocrine system?

network of glands throughout the body what manufactures and secretes hormones

uses blood vessels to deliver hormones to target sites in the body

supplements the work of the nervous system - works with it to regulate the physiological processes of the body

what are endocrine glands?

produce and secrete hormones

regulated by feedback:

1. a signal is send from the hypothalamus to the pituitary gland - ‘releasing hormone’

2. this causes the pituitary gland to secrete a ‘stimulating hormone’ into the bloodstream

3. this hormone then signals the target gland to secrete its hormone

4. as the levels of this hormone rise in the bloodstream, the hypothalamus shuts down the secretion of the ‘stimulating hormone’

5. this slows the secretion of the target gland’s hormone - results in stable concentrations of hormones circulating in the bloodstream

how many endocrine glands are there?

eight major glands

what are hormones?

chemical substances that regulate activity of cells or organs in the body

what do hormones do?

circulate in the bloodstream - carried to target sites throughout the body

affects target cells - cells with receptors for that hormone

when enough receptor cells are stimulated, there is a physiological reaction in the cell

timing of hormone release is critical for normal functioning, as well as the levels released

what is cushing’s syndrome?

caused by too high levels of cortisol

most common cause of excess cortisol is a pituitary gland tumour

what does the pituitary gland do?

produces hormones with the primary function of influencing the release of hormones from other glands to regulate body function

controlled by the hypothalamus - hypothalamus receives information about basic functions and uses it to regulate the function

‘master gland’ - produces hormones to specific targets, directly causes changes in physiological processes in the body or stimulate other glands to produce hormones

high levels of hormones produced in other glands can stop the hypothalamus and pituitary gland from secreting hormones - negative feedback

two main parts - anterior pituitary and posterior pituitary

what does the anterior pituitary do?

secretes ACTH - stimulates the adrenal glands to produce cortisol

secretes luteinising hormone (LT) and follicle-stimulating hormone (FSH) - controls reproductive functioning and sexual characteristics

what does the posterior pituitary do?

releases oxytocin - stimulates contraction of the uterus during childbirth, important for mother-infant bonding

elabd et al (2014) - research in mice has found oxytocin is indispensable for healthy maintenance and repair, and declines with age

what do the adrenal glands do?

above the kidneys

made of two parts:

1. adrenal cortex - outer part of the gland, hormones secreted are essential to life

2. adrenal medulla - inner part of the gland, hormones secreted are not essential to life

what does the adrenal cortex do?

produces cortisol - regulates or supports a range of important bodily functions

cortisol production is increased in response to stress

if cortisol levels are low, the individual will have low blood pressure, poor immune function and an inability to deal with stress

also produces aldosterone - responsible for maintaining blood volume and pressure

what does the adrenal medulla do?

produces adrenaline and noradrenaline

adrenaline helps the body respond to stressful situations by increasing heart rate and blood flow to the muscles and brain, and helping with the conversion of glycogen to glucose to provide energy

noradrenaline constricts blood vessels, causing blood pressure to increase

what do the ovaries do?

part of the female reproductive system

responsible for the production of eggs and the hormones oestrogen and progesterone

maner and miller (2014), progesterone is associated with the heightened sensitivity to social cues that indicate the presence of social opportunity or threat that would be significant during pregnancy

what do the testes do?

male reproductive glands that produce testosterone

testosterone causes the development of facial hair, deepening of the voice and growth spurts that occur during puberty

testosterone production is controlled by the hypothalamus and the pituitary gland

what is the fight or flight response?

mechanism to protect the body against stress and danger

controlled by the sympathetic nervous system, as it controls the necessary bodily functions needed when we are faced with a situation where we may need to fight or flee

how do the sympathetic and parasympathetic nervous systems interact during the fight or flight response?

both systems are constantly shifting the body to more prepared states and more relaxed states

every time a potentially threatening experience occurs, the body reacts - the constant shifting between the two systems keeps the body ready for any situation

what happens when the body detects a threat?

the amygdala is mobilised when there is a threat - associates sensory signals with emotions associated with fight or flight, it then sends a distress signal to the hypothalamus

the hypothalamus functions like a command centre in the brain - communicates with the rest of the body through the sympathetic nervous system

the type of response depends on the type of stressor

what is an acute stressor?

immediate

short term

results in the sympatho-adrenal medullary response (SAM)

what is a chronic stressor?

ongoing

long term

results in the pituitary-adrenal response (HPA)

what is the sympatho-adrenal medullary response (SAM)?

1. a stimulus is registered as an acute stressor in the brain

2. the hypothalamus is activated

3. the sympathetic branch of the ANS is activated

4. the adrenal medulla is stimulated to enlarge and release adrenaline and noradrenaline into the bloodstream

what is the pituitary-adrenal response (HPA)?

1. a stimulus is registered as a chronic stressor in the brain

2. the hypothalamus is activated

3. the pituitary gland is activated - releases ACTH into the bloodstream

4. ACTH causes the adrenal cortex to enlarge and release cortisol - has both positive (e.g. burst of energy, lower sensitivity to pain) and negative (e.g. impaired cognitive performance, lowered immune response) effects on the body

what is the evaluation for the flight or flight response?

‘tend and befriend’ response - taylor et al (2000), women show nurturing behaviours, form alliances with other women, may be that oxytocin inhibits flight

negative consequences - modern stressors rarely require physical activity, repeatedly activating the stress response can be negative, e.g. increased blood pressure can cause heart disease, cortisol suppresses immune response

alternative response - gray (1998), first reaction is to avoid confrontation, ‘freeze response’, adaptive advantage as it focuses attention to choose the best response

positive behaviours in response to stress - von dawans et al (2012), acute stress can lead to cooperative friendly behaviour, e.g. post 9/11, humans are fundamentally social

genetic basis for gender differences - lee and harley (2012), the male SRY gene promotes aggression and causes fight or flight, lack of SRY gene, oestrogen and oxytocin may prevent this response in females

what is localisation of functioning?

the idea that certain functions are localised to certain areas of the brain

what is the motor cortex?

responsible for the generation of voluntary motor movements

located in the frontal lobe along the precentral gyrus

both hemispheres have a motor cortex - controls movements on the opposite side of the body

different parts of the motor cortex control different parts of the body - the regions are arranged logically next to each other

what is the somatosensory cortex?

detects sensory events arising from different regions of the body

located in the parietal lobe, along the postcentral gyrus - dedicated to the processing of sensory information relating to touch

produces sensations of touch, pressure, pain and temperature using sensory information from the skin

both hemispheres have a somatosensory cortex - receives information from the opposite side of the body

what is the visual centre?

visual processing begins in the retina, where light enters and hits the photoreceptors

nerve impulses from the retina are transmitted to the brain via the optic nerve - some travel to areas of the brain involved in coordination of circadian rhythms, most terminate in the thalamus, which acts as a relay station, passing information to the visual cortex

spans both hemispheres and contains several different areas that all process different types of visual information

what is the auditory centre?

mostly in the temporal lobes on both sides of the brain

auditory pathways begin in the cochlear - sound waves are converted to nerve impulses

the nerve impulses travel first to the brain stem, where decoding takes place and then to the thalamus which acts as a relay station and carries out further processing

by the time it arrives at the auditory cortex, sound is mostly decoded

what is broca’s area?

broca treated a patient named ‘tan’, who could understand language but not express it in writing or speaking

studied eight other patients with similar problems and found they all had similar lesions in their left frontal hemisphere

broca (1865) identified a ‘language centre’ in the posterior portion of the frontal lobe of the left hemisphere

fedorenko et al (2012), one part of broca’s area is selectively involved in language, the other in responding to many demanding cognitive tasks

what is wernicke’s area?

located another area of the brain involved in understanding language in the posterior portion of the left temporal lobe

those who had a lesion there could speak but not understand language

what did wernicke propose about the language centres?

language involves separate motor and sensory regions located in different cortical regions

the motor region (broca’s area) is close to the area that controls the mouth, tongue and vocal cords

the sensory region (wernicke’s area) is close to areas of the brain responsible for auditory and visual input

information is thought to be transferred to wernicke’s area where it is recognised as language and associated with meaning

there is a neural loop known as arcuate fasciculus between broca’s area and wernicke’s area

what is the evaluation for localisation of functioning?

individual differences - variation in areas of the brain activated in different individuals during the same task, women have proportionally larger broca’s and wernicke’s areas

equipotentiality theory - extent not location of damage is what is important in loss of functioning

aphasia patients - provide evidence for broca’s and wernicke’s areas

connections are more important than localisation

language production is not localised to just broca’s area

what is hemispheric lateralisation?

each hemisphere had functional specialisations

neural mechanisms for some functions are only found in one hemisphere

inspired by broca and wernicke’s research

what is the corpus callosum?

a bundle of nerve fibres that connects the two hemispheres

what is split brain research?

split brain patients are individuals who have had their corpus callosum cut - originally a treatment for severe epilepsy

what did sperry and gazzaniga (1967) investigate?

the extent to which the hemispheres are specialised for certain functions

tested the capabilities of separated hemispheres by sending information to one hemisphere at a time

what did sperry and gazzaniga (1967) do?

‘describe what you see’ test - when the picture was processed by the left hemisphere, the patient could describe it, but when it was processed by the right hemisphere, they could not describe it

tactile test - when the object was processed by the left hemisphere, the patient could verbally describe it, but when it was processed by the right hemisphere, they could not describe it

drawing task - when the object was processed by the left hemisphere, the picture drawn was not very clear, but when it was processed by the right hemisphere, the picture drawn was clearer

what did sperry and gazzaniga (1967) conclude?

the left hemisphere is dominant in terms of speech and language

the right hemisphere is dominant in terms of visual-motor tasks

connectivity and communication between the two hemispheres is important for effective functioning

what is the evaluation for lateralisation?

advantages of hemispheric lateralisation - multitasking, e.g. chickens looking for food and predators

split brain research is limited - due to small sample sizes and confounding variables reducing validity and reliability

lateralisation is linked to immune system function

individual differences in lateralisation - changes with age

language may not be confined to the left hemisphere - e.g. JW case study

what is plasticity?

the brain’s ability to change and adapt as a result of experience - plays an important role in brain development and behaviour

recent research suggests the brain creates neural pathways in adulthood as well as childhood

what are the causes of plasticity?

life experiences

video games

meditation

how do life experiences cause plasticity?

nerve pathways that are used frequently form stronger connections and neurons that are rarely used eventually die (synaptic pruning)

there is a natural decline in cognitive functioning with age attributed to brain changes

boyke et al (2008), 60 year olds taught to juggle, increased grey matter in the visual cortex, but changes reversed when practicing stopped

how do video games cause plasticity?

can help complex cognitive and motor skills

kuhn et al (2014), increase in synaptic connections in brain areas involved in spatial navigation, strategic planning, working memory and motor performance in those who play video games everyday

how does meditation cause plasticity?

davidson et al (2004), tibetan monks who meditate had more gamma radiation wave activation than those who do not meditate

concluded that meditation causes short-term and permanent changes in the brain

what is functional recovery after trauma?

in the 1960s, researchers studied who stroke victims regained functioning

when brain cells are damaged, the brain rewires itself so some functioning can be regained - other parts of the brain took over for the functions lost, and neurons next to damaged areas formed new circuits that resumed some of the lost functioning

what are the mechanisms for recovery?

neural unmasking

stem cells

how does neural unmasking help recovery after trauma?

wall (1977), ‘dormant synapses’, function is blocked as rate of neural input is too low, but increases in rate of neural input can ‘unmask’ them

can open connections to regions of the brain not normally activated, leading to development of new structures

how do stem cells help recovery after trauma?

stem cells implanted into the brain could directly replace dead or dying cells

transplanted stem cells could secrete growth factors that could ‘rescue’ injured cells

transplanted cells form a neural network that could links uninjured brain sites to damages regions of the brain

what is the evaluation for plasticity?

animal studies - kempermann et al (1998), rats and enriching environments, more neurons in the hippocampus, have to consider limitations of animal studies

human studies - maguire et al (2000), taxi drivers, complex memory training can change the brain

what is the evaluation for recovery after trauma?

animal studies - tajiri et al (2013), stem cells can help regain brain functioning in rats, have to consider limitations of animal studies

age differences - elbert et al (2001), children have a greater capacity for neural reorganisation than adults, increased age makes it harder to make and maintain brain changes

educational attainment - schneider et al (2014), patients with college level education recover quicker from brain injuries, education encourages development of neural pathways

what are the four methods of studying the brain?

post mortem examinations

functional magnetic resonance imaging (fMRI)

electroencephalogram (EEG)

event related potentials (ERP)

what is a post mortem examination?

used to establish underlying neurobiology of particular behaviours

e.g. broca’s work, HM and hippocampus (memory)

established links between psychiatric disorders and brain abnormalities - e.g. cotter et al (2001), there are reduced numbers of glial cells in the frontal cortex of patients with depression

what is functional magnetic resonance imaging (fMRI)?

measures changes in blood flow in particular areas of the brain, which indicates neural activity - active areas of the brain have an increased demand for oxygen, leading to increased blood flow

maps can be produced showing areas of the brain involved in different processes

what are electroencephalograms (EEG)?

measures electrical activity - small electrodes detect small electrical charges resulting from brain cell activity, which are mapped over time to produce EEG data

EEG data is used to detect brain disorders - e.g. epilepsy shows spikes of electrical activity

there are four basic EEG patterns:

1) alpha waves

2) beta waves

3) delta waves

4) theta waves

what are event related potentials (ERP)?

small voltage changes in the brain triggered by stimuli

can be difficult to pick out from other brain activity, so target stimulus is repeated and results are averaged - extraneous neural activity will not occur consistently

there are two categories of ERPs:

1) ‘sensory’ ERPs

2) ‘cognitive’ ERPs

what is the evaluation for studying the brain?

post mortem - detailed anatomical examination, harrison et al (2000), post mortem played a central role in understanding origins or schizophrenia, time, matter of death, length of time from death to post mortem all have an impact, only retrospective

fMRI - non-invasive, no harmful radiation, objective, reliable, not a direct measure as it measures blood flow, overlooks networked nature of brain activity

EEG - provides real time recordings, accurate, useful in clinical diagnoses, cannot reveal deeper regions without implanted electrodes which are not allowed due to ethical implications, difficult to identify exact source of activity

ERP - continuous measure, measures in absence of behavioural responses, requires large number of trials for meaningful data, only strong voltage changes are recordable

what are biological rhythms?

cyclic changes in the way biological systems behave

evolved as the environment has cyclic changes, e.g seasons, day and night - nearly all organisms have biological representations of the 24 hour day

what are circadian rhythms?

biological rhythms that are 24 hours

optimise an organism’s physiology to best meet the varying demands of the day/night cycle

what are circadian rhythms controlled by?

driven by body clocks, which are synchronised by the suprachiasmatic nucleus (SCN) located in the hypothalamus

the SCN is constantly reset, and its primary input is light - photoentrainment

photoreceptors in the eyes send messages about environmental light levels to the SCN - these are used to coordinate activity in the circadian system

what is the sleep-wake cycle?

circadian rhythms determine when sleep and wake periods - maintains a 24-25 hour cycle without external cues

dips and rises - the strongest sleep drives occur from 2-4 am, and 1-3 pm

how does homeostasis affect the sleep-wake cycle?

sleep-wake cycle is also under homeostatic control

as the amount of wake time increases, homeostasis indicates need for sleep is increasing as energy is used up - homeostatic need for sleep increases gradually during the day and peaks in the late eventing

the circadian rhythm keeps us awake during the day and prompts us to sleep when it is dark, and the homeostatic system makes us sleepier as time goes on during the waking period, whether it is night or day

what are the other circadian rhythms?

core body temperature - sleep occurs when core temperature starts to drop, and temperature rises during the last sleep hours, causing alertness

hormone production - melatonin, from the pineal gland, follows a circadian rhythms with peak levels during dark hours

what is the evaluation for circadian rhythms?

research support - hughes (1977), antarctic study, different light levels affected levels of cortisol, other arctic studies found no disruption

individual differences - czeisler et al (1999), length of cycle varies from 13-65 hours, duffy et al (2001) found differences in cycle onset

research methodology - in many studies, participants are not isolated from artificial light, czeisler et al (1999) altered circadian rhythm using dim artificial light

chronotherapeutics - evans and marain (1996), new drug delivery system where they were administered in the evening but not released until dawn

importance of temperature - buhr et al (2010), temperature controls body clock, fluctuates on a 24 hour cycle

what are ultradian rhythms?

rhythms shorter than 24 hours

e.g. sleep stages, basic rest activity cycle

what are the sleep stages?

pattern of alternating REM and NREM sleep - cycle repeats every 90 minutes, different stages have different durations

most knowledge of sleep stages comes EEG recordings of sleep - during deep sleep, brain waves slow, and breathing and heart rate decrease, and during REM, EEG patterns look like awake patterns, and most dreaming occurs in this sleep

what is the basic rest activity cycle (BRAC)?

kleitman (1969) called the 90 minute sleep cycle the BRAC - suggested it occurs during the day, moving from states of alertness to physiological fatigue

we can only focus for 90 minutes - at the end of this the body runs out of resources, resulting in loss of concentration, fatigue and hunger

what are infradian rhythms?

rhythms longer than 24 hours - may last weeks, months, or be annual

e.g. menstrual cycle, organisation of human activities into weeks

what are weekly infradian rhythms?

there are differences in human behaviour that occur on a weekly cycle - e.g. male testosterone is elevated at the weekend, young couples report more sexual activity at the weekend, frequency of births at weekends is higher than weekdays

there are underlying biological cycles that dictate this - halberg et al (2002), seven day rhythms of blood pressure and heart rate, but evidence for this is weak

what are monthly infradian rhythms?

menstrual cycle - variations in length, from 23-36 days (refinetti, 2006), average is 28 days

menstrual cycle is regulated by hormones that promote ovulation or stimulate the uterus for fertilisation

what are annual infradian rhythms?

magnusson (2000) said there is seasonal variation in mood, especially in women - seasonal affective disorder, some become depressed in the winter

there are more heart attacks during the winter

trudeau (1997) - most human deaths occur in january

what is the evaluation for ultradian and infradian rhythms?

individual differences - tucker et al (2007), differences in sleep patterns are biological

research support for BRAC - ericsson et al (2006) found elite violinists practice for only 90 minutes and napped after, also found these patterns in athletes and writers

menstrual cycle and exogenous cues - russell et al (1980), odour donor study, suggests synchronisation of menstrual cycles is affected by pheromones

menstrual cycle and mater preference - penton-voale et al (1999), human mate choice varies across the menstrual cycle

belief in lunar rhythms - arliss et al (2005) found midwives report more babies are born on the full moon, vance (1995) found some mental health professionals believe the full moon affects behaviour, foster and roenneberg (2008), some studies found correlations, but no evidence of causal relationships