bio psyc

• Electrical transmission - the firing of a neuron

  - When neuron in resting state: inside of cell negatively charged

  - When neuron activated: inside becomes positively charged for split-second, causing action potential (create electrical impulse that travels down axon)
• What is synaptic transmission?

  The process by which neighbouring neurons communicate with each other by sending chemical messages across the gap that separates them
• What is chemical transmission?

  - Neural networks: neurons communicate in groups

  - Signals within neurons transmitted electrically

  - Signals between neurons transmitted chemically across the synapse

  - When the electrical impulse reaches end of neuron, it triggers the release of neurotransmitter from tiny sacs, called synaptic vesicles
• Neurotransmitters

  -chemicals that diffuse across the synapse to the next neuron in the chain

  - Once it crosses the gap, it's taken by a postsynaptic receptor site on the dendrite of the next neuron

  - Here chemical message converted back to electrical impulse and transmission begins again

  - Several dozen types identified in brain

  - Each has specific molecular structure that fits perfectly into a postsynaptic receptor site
• excitation and inhibition

  - neurotransmitters either excitatory or inhibitory effect

  - serotonin causes inhibition in receiving neuron, resulting in negative charge

  - Adrenaline causes excitation, increasing positive charge
• What is inhibition?

  When a neurotransmitter, such as serotonin, makes the charge of the postsynaptic neuron more negative. This decreases the likelihood that the neuron will fire and pass on the electrical impulse.
• What is excitation?

  When a neurotransmitter, such as adrenaline, increases the positive charge of the postsynaptic neuron. This increases the likelihood that the neuron will fire and pass on the electrical impulse.
• What is summation?

  - Decides Whether a postsynaptic neuron fires

  - Excitatory and inhibitory summoned

  - Action potential of the postsynaptic neuron is only triggered, if the sum of the excitatory and inhibitory signals at any time
• What is event related potentials?


  -Brain waves that are triggered by particular events

  -Use extraneous brain activity from EEG recording, leaving response to specific stimulus

  -General measure of brain activity

  -Neural responses associated with specific sensory, cognitive and motor events
• What is a post-mortem exam?

  - Analysis of persons brain following death

  - Most likely to have rare disorder or unusual mental processes

  - Can establish likely cause of affliction
• Evaluation of functional magnetic resonance imaging


  strength: doesn't rely on radiation, risk, free, non-invasive, high, spatial resolution

  Limitation: expensive, poor temporal resolution (five second time lag) , not moment to moment
• Evaluation of electroencephalogram


  strengths: study stages of sleep, high temporal resolution, detect brain activity at a resolution of a single millisecond

  Limitation: can't pinpoint exact source of neural activity, so can't distinguish between activities originating in adjacent locations
• Evaluation of event related potentials


  Strength: excellent, temporal resolution, measures, cognitive functions and maintenance of working memory

  Limitation: lack of standardisation, background noise and extraneous material needs to be completely eliminated
• Evaluation of post-mortem exams


  strengths: broca and wernicke relied on this, understanding Key processes in the brain, provides useful information

  Limitation: trauma order decay, ethical issues with informed consent
• What is hemispheric lateralisation?


  The idea that the two halves of the brain are functionally different and that certain mental processes and behaviours are mainly controlled by one hemisphere rather than the other.
• What is lateralisation?


  There are two sides of the brain called hemispheres
• The left hemisphere


  -brocas area left frontal lobe

  -wernickes area left temporal lobe

  - Language

  - analyser

  - Controls movement on the right

  - RVF Of both eyes
• The right hemisphere


  - Only produce rudimentary words

  - Synthesiser

  - Controls movement on left side of body

  -LVF of both eyes
• Strengths of hemispheric lateralisation

  lateralisation in the normal brain: research supports, shows two hemispheres process information differently. fink et al: used pet scans to see w which brain area is active during visual processing task, global elements RH more active but finer details LH more active
• Limitation of hemispheric lateralisation


  One brain: research shows people don't have dominant side of brain. nielsen et al: analysed brain scans from over 1000 ppl age 7-29 and no evidence of a dominant side
• What happens in split brain operation?


  -severing connections between the RH and LH, mainly the corpus callosum.

  -surgical procedure used to reduce epilepsy

  -During epileptic seizure the brain experiences a major electrical storm which travels from one hemisphere to the other
• Sperry's procedure on split brain


  - 11 split brain individuals studied were image or word could be projected onto a persons RVF and the same or different image could be projected to the LVF.

  -normal brain= corpus callosum immediately share information to both hemispheres. Split brain= information can't be conveyed from hemisphere to another
• Sperry's findings on split brain

  -when objects shown to RVF participant could describe what was seen, couldn't if shown to LVF

  -This is because messages from our RHO relayed to language centres in LH.

  -Although couldn't give verbal labels to objects projected by LVSD code select a matching object out of sight using the left hand

  -Picture shown to LVF triggers emotional reaction but report seeing nothing
• Strength of split brain research


  -research support:gazzaniga: split brain perform better on certain tasks, e.g. faster at identifying odd one out of similar objects

  -this is because in normal brain LHs cognitive strategies are watered down by the inferior RH

  -Supports sperry findings that the left and right brain are distinct
• Limitation of split brain research


  - generalisation issues: Sperrys, participants compared to Neurotypical control group- none of them had epilepsy (cofounding variable)

  -Differences may have been a result of epilepsy rather than split brain
• what is involved in circadian rhythms


  -biological rhythms

  -Sleep/wake cycle

  -siffres cave study

  - other research
• circadian rhythms: biological rhythms


  -distinct patterns of changes in body activity that conform to cyclical time periods

  - Governed by two things: bodies, internal biological clock (endogenous pacemakers) and changes in the environment (exogenous zeitgebers)

  -Some rhythm occur a lot during day (ultradian rhythms) and some take longer than a day (infradian rhythm)
• circadian rhythms: the sleep/wake cycle


  -example of circadian rhythms

  -effect of daylight on when we sleep (exogenous zeitgeber)

  -Effect of biological clock called "suprachiasmatic nucleus" which provides information from the eye about light
• circadian rhythms: siffres cave study


  - self styled caveman, who spent extended periods underground to study effects of his own biological rhythms

  -Deprived of natural light on sound, two months in the caves

  - His free running, biological rhythm settle down to one that was just beyond the usual 24 hours, fell asleep and woke up on a regular schedule
• circadian rhythms: other research (ww2)


  -Aschoff & Wever: Group of ppts spend 4 weeks in a WWII bunker

  -All but one displayed circadian rhythm of 24 -25hrs (other extended to 29hrs)

  -Suggests (along with Siffre's study) that 'natural' sleep/wake cycle may be longer than 24hrs

  -Entrained by exogenous zeitgebers associated with 24hr day e.g. daylight hours, mealtimes)
• circadian rhythms: other research (cave)


  -Should not overestimate influence of environmental cues on internal biological clock

  -Folkard et al: 12 ppts agreed to live in dark cave for 3 weeks

  -Sleep 11:45pm wake 7:45am

  -Gradually sped up clock, day became 22 hours

  -Only one ppt comfortably adjusted

  Suggest existence of strong free-running circadian rhythm not easily overridden
• strength of circadian rhythms


  -hift work- desynchronisation of biological rhythms. bolwin; shift worker experienced a lapse of concentration around 6am so more accidents would occur, links shift work and poor health were 3x were likely to develop heart disease thus the sleep-wake cycle may have economic implications terms of how best to manage shift workl

  -medical treatment - co-corordinate the body's basic process with implications for chronotherapeutics, aspirin reduces heart attack, most likely took in the morning found taking aspirin is the most effective last thing on night, helps increase the effectiveness of drug treatments
• Limitations of circadian rhythms


  -individual differences; generalisations difficult to make. studies based on small samples. Duffy et al; some ppl natural preference to sleep early (larks) and some late (owls)
• What are infradian rhythms?


  A type of biological rhythm with a frequency of less than one cycle in 24 hours, such as menstruation and seasonal affective disorder.
• infradian rhythms; the menstrual cycle


  -typical cycle; 28 days

  -rising level of oestrogen cause egg to release (ovulation)

  -after ovulation, progesterone helps womb lining to grow thicker and ready for pregancy

  -if not pregnant womb lining comes away as period
• infradian rhythms; synchronising the menstrual cycle


  -stern and mcclintock; 29 women at diff stages of cycle, pheromones gathers from cotton pad in armpit (worn for 8 hours). treated with alcohol and frozen and rubbed on upper lip of participants.

  -68% women experienced changes to their cycle which brought them closer to cycle of "odour donor"
• infradian rhythms; seasonal affective disorder


  -persistent low mood, winter blues as daylight hours become shorter

  -circannual rythym as once a yesr

  -caused by hormone melatonin- during night the pineal gland secretes melatonin until increase in light- eg longer in winter so has knock on effect on serotonin in the brain
• infradian rhythms; strength


  -explained by natural selection, menstrual cycle has evolutionary value. in old days adventurous for females to menstruate. babies who lost mums to access breast milk
• infradian rhythms; limiattions


  -methodological limitations; many factors that effect change in menstrual cycle (stress, diet, exercise), act as cofounding variable. other studies failed to replicate findings
• what are ultradian rhythms


  - Cycles that last less than 24 hours e.g. sleep cycle which repeats every 90-100 minutes