AQA Psychology - Biopsychology (imported)

6 mark structure for reflex actions

stimulus
receptor
sensory neurone
relay neurone
motor neurone
effector
response

action potential

• occurs when a neuron sends information down an axon, away from the cell body
• it is an explosion of electrical activity, meaning we go from a resting potential to an action potential due to a stimulus

adrenal gland

split into two parts
adrenal medulla - secretes adrenaline and noradrenaline
adrenal cortex - secretes cortisol

• adrenaline and noradrenaline are responsible for the fight or flight response, they bring alertness and readiness
• cortisol stimulates the release of glucose

auditory cortex

in the temporal lobes on each hemisphere, processes speech information, and will send this to the Wernicke's area

Autonomic Nervous System (ANS)

• governs vital internal functions in the body, such as, breathing, heart rate, digestion, body temp and stress responses
• regulates involuntary actions
  two main subdivisions are;
• the sympathetic nervous system
• the parasympathetic nervous system

axon

• where the electrical signals pass along

axonal sprouting

the growth of new nerve endings which connect with other undamaged nerve cells to form new neuronal pathways

biological rhythms

• all living organisms (plants, animals, and people) are subject to biological rhythms, and these exert an important influence on the way in which the body systems behave
  all biological rhythms are governed by:
  endogenous pacemakers
  exogenous zeitgebers
• some of these rhythms occur many times throughout the day (ultradian rhythms)
• others take longer than a day to complete (infradian rhythms)

brain plasticity

• the brain is described as 'plastic' because it has the ability to change throughout life
• during infancy, the brain experiences a rapid growth in the number of synaptic connections it has
• as we age, rarely used connections are deleted, and frequently used connections are strengthened (through the process of synaptic pruning)
• synaptic pruning enables lifelong plasticity where new neural connections are formed in response to new demands on the brain

Broca's area

• located in the frontal lobe of the left hemisphere
• named after French surgeon, Paul Broca
• this area is in the left hemisphere and plays a role in speech production
• damage to the area can lead to Broca's aphasia, a disorder which means patients can understand language but have difficulties speaking (can usually only manage a few simple words)

case study for Broca's area

• Tan could understand spoken language but was unable to pronounce any coherent words and could only say 'tan'
• after Tan's death Broca conducted a post-mortem exam on Tan's brain and discovered he had a lesion in the left frontal lobe

case study for localisation of function

Phineas Gage

• a rod penetrated Gage's left cheek, tore through his brain, and exited his skull
• Gage not only survived the initial injury but was able to speak and walk to a nearby cart so he could be taken into town to be seen by a doctor
• despite surviving his personality and behaviour were so changed as a result of the frontal lobe damage that many of his friends described him as an almost different person entirely
• the impact that the accident had has helped us better understand what the frontal lobe does, especially in relation to personality

Central Nervous System (CNS)

• made up of the brain and spinal cord
• the brain is the centre of all conscious awareness and controls psychological processes
• the spinal cord is an extension of the brain and is responsible for reflex actions

cerebral cortex

• the body's ultimate control and information-processing centre
• responsible for the higher level processes of the brain; including memory, reasoning, decision making

circadian rhythms

The 24-hour biological cycles found in humans and many other species
examples;
sleep/wake cycle
core body temperature

core body temperature

• varies around 2 degrees during the course of the day
• at its lowest around 4am (36ºC) and peaks around 6pm (38ºC)
• evidence suggests that body temp may have an effect on our mental abilities, the warmer we are internally, the better our cognitive performance
• Folkard demonstrated how children who had stories read to them at 3pm showed superior recall and comprehension after a week, compared to children who heard the same stories at 9am

dendrite

• receives the nerve impulse or signal from adjacent neurons

denervation supersensitivty

• after damage, remaining synapses become more responsive and easily stimulated
• axons become aroused to a higher level to compensate for lost ones
• this can have a negative impact on oversensitivity to messages, such as pain

different tasks within Sperry and Gazzangia's experiment

describe what you see task - a picture was presented to either the LVF or the RVF and the participant had to describe what they saw
tactile task - an object was placed in the patients left or right hand and they had to either describe what they felt or select a similar object from a series of alternate objects
drawing task - participants were presented with a picture in either their LVF or RVF, and they had to draw what they saw

EEG

• EEGs measure electrical activity within the brain via electrodes that are fixed to an individuals scalp
• the scan recording represents the brain wave patterns that are generated from the action of millions of neurons
• EEG is often used by clinicians as a diagnostic tool as unusual patterns may indicate neurological abnormalities

EEG evaluation

strengths:

• proved invaluable in the diagnosis of conditions such as epilepsy
• has contributed to understanding of the stages of sleep
• high temporal resolution; EEG's can detect brain activity at resolution of a single millisecond.
  limitations:
• EEG produces a generalised signal from thousands of neurons. Difficult to know the exact source of neural activity

electric transmission

• when a neuron is in a resting state the inside of the cell is negatively charged compared to the outside
• when a neuron is activated, the inside of the cell becomes positively charged for a split second causing an action potential to occur
• this creates an electrical impulse that travels down the axon towards the end of the neuron

endocrine system

• the body's "slow" chemical communication system
• works alongside the nervous system to control vital functions in the body
• different glands in the body produce hormones
• hormones are secreted into the blood stream and affect any cell in the body that has a receptor for that particular hormone
• most hormones affect cells in several organs or throughout the entire body, leading to drivers and powerful responses
• e.g thyroid gland produces thyroxine, this hormone affects cells in the heart, it also affects cells throughout the body, increasing metabolic rates, this in turn affects growth rates

endogenous pacemakers

Internal body clocks that regulate many of our biological rhythms.

endogenous pacemakers and the sleep wake cycle

• the suprachiasmatic nucleus (SCN) is an example of an endogenous pacemaker
• a bundle of cells in the hypothalamus embodying the internal clock, which drives the circadian rhythm
• it is influential in maintaining the sleep wake cycle
• the SCN lies just above the optic chasm, it receives information about light from this structure
• this continues even when our eyes are closed, enabling the biological clock to adjust to patterns of daylight whilst we are asleep

ERPs

• using a statistical averaging technique, all extraneous brain activity from the original EEG recording is filtered out, leaving only the responses that relate to, say, the performance of a specific task
• what remains are ERPs; types of brainwave that are triggered by particular events
• research has revealed many different forms of ERP and how, for example, these are linked to cognitive processes

ERPs evaluation

strengths:

• ERP's are more specific than can be achieved using raw EEG data.
• Good temporal resolution.
• Researchers have been able to identify many types of ERP and describe their precise role
  limitations:
• lack of standardisation in methods between studies makes it difficult to confirm findings.
• background noise and extraneous material must be completely eliminated, which may not always be easy to achieve.

evaluation of circadian rhythms

strengths:

• understanding circadian rhythms helps determine best time to administer drug treatments, e.g. heart attack risk greatest in early morning so drugs taken at night; research has revealed peak times for administration and dosage of drugs
• support from other studies; Siffre and Folkard

limitations:

• poor control of studies; exposure to artificial light in cave studies such as torches was not controlled, it was assumed that only natural light has an influence on biological rhythms, however Czeisler found dim artificial lighting could adjust the circadian rhythm between 22-28hours
• issues with case study evidence and small samples; Siffre study was only one person, and Folkard study was conducted on only a handful of people. Consequently it is impossible to generalise results to whole population
• individual differences; e.g. Siffre noted that when he went into cave at 60, his body responded differently with his body clock following more of a 48hr cycle, this suggests results cannot be generalised from such a small sample onto everyone, as factors such as age and gender may have significant impact on our circadian rhythms.

evaluation of endogenous pacemakers

strengths:

• support from animal studies

limitations:
research may obscure other body clocks - research has revealed that there are numerous circadian rhythms in many organs and cells in the body. These peripheral oscillators are found in the organs; including the lungs, pancreas and skin. They are influenced by the actions of the SCN, but also act independently. Damiola et al demonstrated how changing feeding patterns in mice could alter the circadian rhythms of cells in the liver by up to 12 hours, whilst leaving the rhythm of the SCN unaffected. This suggests other complex influences on the sleep wake cycle.
endogenous pacemakers cannot be studied in isolation - total isolation studies, such as Siffre's cave study are extremely rare. Siffre made use of artificial light which could have reset his biological clock every time he turned his lamp on. In everyday life, pacemakers and zeitgebers interact, and it makes little sense to separate the two for the purpose of research. This suggests the more researchers attempt to isolate the influence of internal pacemakers, the lower the validity of the research.

evaluation of exogenous zeitgebers

strengths:

• support from Campbell and Murphy

limitations:
exogenous zeitgebers do not have the same effect in all environments - the experience of people who live in places where there is very little darkness in summer and very little light in winter contradicts the importance of exogenous zeitgebers. For instance, people who live within the Arctic Circle have similar sleep patterns all year round, despite spending around six months in almost total darkness. This suggests the sleep wake cycle is primarily controlled by endogenous pacemakers that can override environmental changes in light.
there is evidence challenging the role of exogneous zeitgebers - Miles et al studied a young man, blind from birth, who had an abnormal circadian rhythm of 24.9 hours. Despite exposure to social cues, such as regular mealtimes, his sleep/wake cycle could not be adjusted. This suggests that social cues alone are not effective in resetting the biological rhythm.

evaluation of functional recovery

strength:
real world application - understanding processes involved in plasticity has contributed to the field of neuron rehabilitation, it encourages new therapies to be tried; e.g. constraint induced movement therapy is where stroke patients repeatedly use the affected part of their body, whilst the unaffected part is restrained

limitation:
cognitive reserve/level of education can influence recovery - Schneider et al revealed that the more time people with a brain injury had spent in education (taken as an indicative of their cognitive reserve) the greater their chances of a disability free recovery (DFR); 40% of those who achieved DFR had over 16yrs of education, compared to about 10% who had less than 12yrs
Elbert et al - concluded that the capacity for neural reorganisation is much greater in children than in adults, meaning that neural regeneration is less effective in older brains. This may explain why adults find change more demanding than younger people do. Therefore, we must consider individual differences when assessing the likelihood of functional recovery in the brain after trauma.

evaluation of infradian rhythms

strength:
menstrual synchrony research can be explained by natural selection - synchronisation of the menstrual cycle is thought by some to have evolutionary value, for our distant ancestors it may have been advantageous for women to menstruate together and become pregnant at the same time. In a social group, this would allow babies who had lost their mothers during or after childbirth to have access to breast milk, thereby improving their chances of survival. This suggests that synchronisation is an adaptive strategy.

limitation:
synchronisation studies have methodological shortcomings - there are many factors that may effect change to the menstrual cycle, including stress, changes in diet, exercise, etc. These may act as confounding variables, which means that any supposed pattern of synchronisation is no more than would have been expected to occur by chance. This may explain why other studies have failed to replicate the findings. This suggests that menstrual synchrony studies are flawed.
treatments for seasonal affective disorder - light therapy, a box which simulates very strong light to reset the body's internal clock is supposed to be effective. Studies show this helps reduce the effects of SAD in about 80% of people (Sanassi). Light therapy is also preferred over antidepressants to treat SAD because it is regarded as safe. However, light therapy can produce headaches and eye strain. Rohan et al recorded a relapse rate of 46% over successive winters, compared to 27% in a comparison group receiving CBT.

evaluation of lateralisation

strengths:
research support - Sperry's study supports the idea of lateralisation
methodology - the experiment used standardised, well controlled procedures

limitations:
split brain surgery is a rare procedure - data on lateralisation may not be generalisable e.g. only 10-15 patients have been systematically studied after a split-brain operation
data from the studies may lack ecological validity - this is because Sperry's methodology was artificial e.g. in real life a severed corpus callosum can be compensated for by use of two eyes
theoretical bias - psychologists debate on whether we are all two minds, and that the split brain procedure only emphasises this, whilst other psychologists believe that the two hemispheres form a highly integrated system
issues with generalisation - there were only 11 participants, all of whom had a history of epileptic fits, whilst the control group had no history of epilepsy; so epilepsy could be the cause of some of the changes
process of split-brain patients' surgery may have had additional effects other than severing the corpus callosum - conclusions on lateralisation may be confounded by extraneous damage e.g. the behaviour of the split-brain patients may be due to damage caused by severing smaller pathways

evaluation of localisation theory

Strength;

• Petersen used brain scans to demonstrate how Wernicke's area was active during a listening task and Broca's area was active during a reading task.
• Buckner and Petersen reviewed long-term memory studies and found that semantic and episodic memories reside in different parts of the prefrontal cortex. Therefore objective methods for measuring brain activity have provided scientific evidence that many brain functions are localised.

Limitation;

• Lashley removed areas of the cortex (between 10% and 50%) in rats that were learning the route through a maze. No area was proven to be more important than any other area in terms of the rats' ability to learn the route. The process of learning seemed to require every part of the cortex rather than being confined to a particular area. This suggests that higher cognitive processes, such as learning, are not localised but distributed in a more holistic way in the brain. He proposed the equipotentiality theory, which suggests that the basic motor and sensory functions are localised, but that higher mental functions are not. He claimed that functions are not localised to just one region, as other regions can take over specific functions following brain injury.
• Dronkers conducted an MRI scan on Tan's brain, to try to confirm Broca's findings. Although there was a lesion found in Broca's area, they also found evidence to suggest other areas may have contributed to the failure in speech production.

evaluation of plasticity

strengths:
Maguire
research support - Kempermann et al investigated whether an enriched environment could alter the number of neurons in the brain. He found an increased number of neurons of rats in complex enviroments rather than cages

limitation:
plasticity may have a negative effect on behavioural consequences - Medina found that the brains adaption to prolonged drug use leads to poorer cognitive functioning in later life, as well as an increased risk of dementia
the brains ability to adapt to damage is not always beneficial - Ramachandran and Hirstein found phantom limb syndrome (experienced by 60-80% of amputees) is due to cortical reorganisation in the somatosensory cortex that occurs as a result of limb loss and leads to the unpleasant and painful sensations

evaluation of ultradian rhythms

strength:
improved understanding of age-related changes in sleep - sleep scientists have observed that slow wave sleep (SWS) reduces with age. Growth hormone is mostly produced during SWS therefore this is reduced in older people. According to Eve Van Cauter et al, the resulting sleep deficit may explain various issues in old age, such as reduced alertness. In order to increase SWS, relaxation and medication may be used. This suggests that knowledge of ultradian rhythms has practical value.
control of extraneous variables - a researcher can exclude temporary variables such as noise or temperature that may affect sleep

limitation:
significant variation between people - Tucker et al found large differences between participants in terms of the duration of each sleep stage, particularly stages 3 and 4. Tucker et al suggest that these differences are likely to be biologically determined. This makes it difficult to describe 'normal sleep' in any meaningful way.
artificial environment/lack ecological activity - lab studies involve being attached to complicated machinery, leading participants to sleep in a way that does not represent their ordinary sleep patterns

excitation and inhibition

• neurotransmitters can be excitatory or inhibitory
  excitatory - make it more likely the next neuron will 'fire' (e.g adrenaline)
  inhibitory - make it less likely the next neuron will 'fire' (e.g serotonin)
• normal brain function depends upon a regulated balance between excitatory and inhibitory influences

exogenous zeitgebers

external cues that may affect or entrain our biological rhythms, such as the influence of light on the sleep/wake cycle

exogenous zeitgebers and the sleep wake cycle

• external factors in environment that reset biological clocks through entrainment
• for example, light and social cues

female menstrual cycle

• monthly infradian rhythm
• regulated by hormones
• ovulation occurs (roughly half way through the cycle) when oestrogen levels are highest, usually lasts 16 to 32hrs
• after ovulation, progesterone levels increase, ready for possible embryo implantation
• a typical menstrual cycle is approximately 23 to 36 days

fight or flight response

• anxiety and fear are important for survival because they act as a mechanism to protect the body against stress and danger
• the SYMPATHETIC NERVOUS SYSTEM controls the 'fight or flight' phenomenon
• it controls the bodily changes needed when we are faced with a situation where we may need to defend ourselves

findings of different tasks within Sperry and Gazzangia's experiment

describe what you see task - the patients could describe what they saw when the picture was presented to the RVF (processed by the LH), but not when it was presented to the LVF (processed by the RH)
tactile task - the patients could describe or identify the object when placed in their right hand (processed by the LH), but not when placed in their left hand (processed by the RH)
drawing task - the left hand (controlled by the RH) would consistently draw clearer and better drawings than the right hand (controlled by the LH), even though all participants were right handed

fMRI

• detects changes in blood oxygenation and blood flow that occurs as a result of neural activity in specific parts of the brain
• when a brain area is more active it consumes more oxygen, to meet this increased demand blood flow is directed to the active area
• fMRI produces 3D images showing which parts of the brain are involved in a particular mental process

fMRI evaluation

strengths:

• it is non invasive, doesn't rely on use of radiation and is safe, allows more patients to undertake fMRI scans and so researchers can learn more
• It produces images with high spatial resolution, showing detail by the millimetre.
  limitations:
• is expensive compared to other techniques and can only capture a clear image if the person stays still.
• poor temporal resolution because of 5 second lag between initial neural activity and image
• can only measure blood flow in the brain, can't home in on the activity of individual neurons
• can't infer causation of changes in blood flow

frontal lobe

The lobe at the front of the brain associated with movement, speech, and impulsive behaviour.
Motor cortex is located here

functional recovery; after brain trauma

• following physical injury, or other forms of trauma such as the experience of a stroke, unaffected areas of the brain are often able to adapt and compensate for those areas that are damaged
• the functional recovery that may occur in the brain after trauma is an example of neural plasticity
• healthy brain areas may take over the functions of those areas that are damaged, destroyed or even missing
• neuroscientists suggest that this process can occur quickly after trauma (spontaneous recovery) and then slow down after several weeks or months
• at this point the individual may require rehabilitative therapy to further their recovery.

holistic theory of the brain

• all parts of the brain were involved in the processing of thought and action
• the functions of the brain are as a result of the brain working as a whole
• according to this theory functions can't be assigned to specific brain regions

hypothalamus

stimulates and controls the release of hormones from the pituitary gland

infradian rhythms

• biological rhythms that last longer than 24 hours
• can be weekly, monthly, or annually
• examples; female menstrual cycle, seasonal affective disorder

key assumptions

• bio psychologists assume that behaviour and experiences are caused by activity in the nervous system

lateralisation

The idea that the two halves of the brain are functionally different and that certain processes or behaviours are controlled by one hemisphere rather than the other

left and right hemispheres

• for most of us, language is (lateralised) based in the left hemisphere (LH)
• the right hemisphere can only produce rudimentary words and phrases
• the right hemisphere (RH) is more engaged with perceptual tasks and even some emotional tasks, like reading facial expressions
• the LH is the analyser and the RH the synthesiser
• many functions are not lateralised (vision, motor and somatosensory areas appear in both hemispheres)

left hemisphere

controls the right side of the body; analytical, language, math

left side of the brain

controls the right side of the body

light

• an example of an exogenous zeitgeber
• it can reset the body's main endogenous pacemaker, the SCN, and plays a role in the maintenance of the sleep/wake cycle
• it also has an indirect influence on key processes in the body that control functions such as hormone secretion and blood circulation
• the SCN sends signals to the pineal gland, which leads to an increase in the production of melatonin at night, helping to induce sleep
• the SCN and pineal glands work together as endogenous pacemakers; however, their activity is responsive to the external cue of light
• Campbell and Murphy demonstrated that light may be detected by skin receptor sites on the body even when the same information is not received by the eyes

localisation of function

• The theory that different areas of the brain are responsible for different behaviours, processes or activities.
• Different functions are localised in certain areas

motor cortex

at the back of the frontal lobe, located on each hemisphere, and controls voluntary movement in the opposite side of the body

motor neuron (brief outline)

function - carries messages from the CNS to effectors such as muscles and glands
length of fibres - short dendrites and long axons

motor neurons

• located in the CNS
• project their axons outside the CNS
• directly or indirectly control muscles
• when stimulated, they release neurotransmitters that bind to receptors on the muscle and trigger a response which leads to muscles movement

myelin sheath

• insulates/protects the axon from external influences that might effect the transmission of the nerve impulse down the axon

neurons

• basic building blocks of the nervous system
• cells that conduct nerve impulses
• things that people think, feel, say, and are caused by electrochemical events occurring within and between the neurons

neurotransmitters

• chemicals that diffuse across the synapse to the next neuron
• each has a specific molecular shape that fits perfectly into a post synaptic receptor site
• each neurotransmitter has a specific function
• they affect the transfer of an impulse to another nerve or muscle
• these neurotransmitters are 'taken back up' into the terminal buttons of neurons through the process of reuptake
• or they are broken down by an enzyme

nodes of ranvier

• gaps in the myelin sheath that speed up the transmission of the impulse by forcing it to 'jump'

nucleus

• Control centre of the cell
• Contains the DNA

occipital lobe

A region of the cerebral cortex that processes visual information
Visual cortex is located here

ovaries

• secrete oestrogen and progesterone
• oestrogen and progesterone regulate the menstrual cycle and reproduction

parasympathetic nervous system

• relaxed state

• constricts pupils

• inhibits heart

• dilates arteries

• constricts bladder

parietal lobe

Portion of the cerebral cortex lying at the top of the head and toward the rear; receives sensory input for touch and body position
Somatosensory cortex is located here

parts of a neuron

cell body, dendrites, axon, nucleus, nodes of ranvier, myelin sheath, terminal buttons

Peripheral Nervous System (PNS)

• transmits messages via millions of neurons (nerve cells) to and from the CNS
  subdivided into;
• the somatic nervous system
• the autonomic nervous system

physiological changes of fight or flight

• the SYMPATHETIC NERVOUS SYSTEM sends a signal to the adrenal medulla which responds by releasing the hormone adrenaline into the bloodstream
• adrenaline causes the heart to beat faster, pushing blood to the muscles, heart and other vital organs
• blood pressure increases
• breathing becomes rapid in order to take in as much oxygen as possible
• blood sugar (glucose) and fats are released into the bloodstream, supplying energy to parts of the body associated with fight or flight
• this is known as the acute response to stress

pineal gland

• secretes melatonin
• melatonin regulates our sleep/wake schedule

pituitary gland

the master gland controls the release of hormones from all the other endocrine glands in the body
split into two;
anterior - secretes adrenocortical trophic hormone (ACTH)
posterior - secretes oxytocin

• ACTH stimulates adrenal cortex and triggers the production of cortisol (the stress hormone)
• oxytocin is responsible for uterus contractions during childbirth, and affects romantic attraction (the love hormone)

post mortem examinations

• Analysing the brain following death.
• Usually occurs in a patient who has experienced a rare disorder or unusual deficits in cognitive processes during their lifetime
• The areas of damage in the brain are examined to establish the likely cause of harm.
• They compare this with neurotypical brains to establish the differences

post mortem examinations evaluation

strengths:

• vital in providing a foundation for early understanding of key processes
• Broca and Wernicke relied on post mortem examinations to establish links between language, brain, and behaviour decades before neuroimaging became possible
  limitations:
• causation is difficult to establish, observed damage to the brain may not be linked to the deficits under review, but to some unrelated trauma
• there are ethical issues as patients may not be able to provide informed consent before death

recruitment of homologous areas on the opposite side of the brain

• for example, if Broca's area on the left side was damaged, the right sided equivalent would carry out its functions
• over time functionality may shift back

relay (interconnecting) neuron (brief outline)

function - transfers messages from sensory neurons to other interconnecting neurons or motor neurons
length of fibres - short dendrites and short or long axons

relay neurons

• lie somewhere between the sensory input and motor output
• located in the brain and spinal cord
• allow sensory and motor neurons to communicate with each other

research into plasticity

• Maguire et al (2000) studied the brains of London taxi drivers and compared them against a control group

• they found significantly more volume of grey matter in the posterior hippocampus in the taxi drivers than in a matched control group

• this part of the brain is associated with the development of spatial and navigational skills in humans and other animals

• this is because taxi drivers have to remember the map of London's streets as part of their training

• this training alters their brain structure

• Maguire also found that the longer they have this job, the more pronounced the structural differences

• this is supported by Draganski et al who observed similar learning induced changes in the brains of medical students, 3 months before and after their final exams

research into the SCN

animal studies;
De Coursey et al - destroyed the SCN connections in the brain of 30 chipmunks who were then observed in their natural habitat for 30 days, their sleep wake cycle disappeared and a large amount were killed by predators because they were awake and vulnerable when they should've been asleep
Shows the SCN plays a major role in our circadian rhythms

Ralph et al - bred mutant hamsters with 20hrs sleep wake cycle, when SCN from mutant hamsters was transplanted to healthy hamsters their sleep wake cycle defaulted to 20hrs

research support for circadian rhythms

Siffre - lived in cave for 7 months, no concept of time, day or date; slept and ate when he felt like it, his sleep wake cycle became 25hrs

• this suggest that the 'natural' sleep wake cycle may be slightly longer than 24 hours but that it is entrained by exogenous zeitgebers associated with our 24-hour day (such as the number of daylight hours, typical mealtimes, etc.)

Folkard - isolated 12 participants from natural light, they slept at 11:45 and woke at 7:45; he gradually changed the clocks unbeknown to the participants, so days changed to 22hrs. Only one participant could adjust comfortably.

• this suggests the existence of a strong free-running circadian rhythm that cannot easily be overridden by exogenous zeitgebers

right hemisphere

controls the left side of the body; creative, intuitive, spacial

right side of the brain

controls the left side of the body

seasonal affective disorder (SAD)

• a depressive disorder with a seasonal pattern.
• often called the 'winter blues' because the symptoms are triggered during the winter months when the number of daylight hours becomes shorter.
• symptoms include those associated with depression; loss of interest, low mood, anxiety, fatigue, difficulty concentrating
• SAD is an infradian rhythm (called a circannual yearly cycle).
• during the night, the pineal gland secretes melatonin until dawn when there is an increase in light.
• during winter, the lack of light in the morning means secretion goes on for longer.
• this has an indirect effect on the production of less serotonin in the brain (linked to depressive symptoms)

sensory neuron (brief outline)

function - carries messages from the PNS to the brain and spinal cord (CNS)
length of fibres - long dendrites and short axons

sensory neurons

• carry sensory receptors (e.g vision, taste) to the spinal cord and the brain
• convert information from these sensory receptors into neural impulses
• when these impulses reach the brain they're translated into sensations (e.g pain) so an appropriate response can be made
• some neurons don't travel to the brain and terminate at the spinal cord, this allows reflex actions to occur quickly without the delay of sending impulses to the brain

sleep/wake cycle

• dictates when humans and animals should be asleep/awake
• light provides the primary input on our sleep/wake cycle, acting as an external cue (exogenous zeitgebers)
• the sleep/wake cycle is also governed by an internal cue (endogenous pacemaker) called the suprachiasmatic nucleus (SCN)
• the SCN receives information from the eye about brightness levels/light
• exogenous zeitgebers (light) can reset the SCN
• homeostasis is also involved, when an individual has been awake a long time, homeostasis tells the body there is a need for sleep because of energy consumption

social cues

• new born babies sleep wake cycle is quite random
• at about 6 weeks the circadian rhythms begin, and by 16 weeks rhythms have been entrained by the schedules imposed by parents, including mealtimes and bedtimes
• research on jet lag suggests that adapting to local times for eating and sleeping (rather than responding to one's own feelings of hunger and fatigue) is an effective way of entraining circadian rhythms and beating jet lag when travelling

Somatic Nervous System (SNS)

• part of the PNS
• controls skeletal muscles and movement
• responsible for carrying sensory and motor information
• sensory neurons relay messages TO the CNS
• motor neurons relay messages FROM the CNS

somatosensory cortex

at the front of the parietal lobe on each hemisphere, sensory info from the receptor sites on the skin is processed here, each body part has a different area in the somatosensory cortex, the more sensitive the body part is, the larger the area it has

Sperry and Gazzaniga's research into lateralisation

procedure

• 11 people with a split brain operation were studied
• an image was projected to a patients left visual field (LVF) which is processed by the patients right hemisphere, or the right visual field (RVF) which is processed by the patient's left hemisphere
• when information is presented to one hemisphere in a split brain patient, the information is not transferred to the other hemisphere (as the corpus callosum is cut)

split brain research

• a split brain operation involves severing the connections between the RH and the LH, mainly the corpus callosum
• this is a surgical procedure used to reduce epilepsy
• during an epileptic seizure the brain experiences excessive electrical activity which travels from one hemisphere to the other
• to reduce fits, these connections are cut, splitting the brain
• the split brain research studies how the hemispheres function when they can't communicate with each other.

stages of sleep

• changes between rapid eye movement (REM) and non rapid eye movement (NREM) which repeat every 90minutes
  stages:
  1 and 2 - light sleep; during these stages brainwave patterns become slower and more rhythmic, starting with alpha waves and progressing to theta waves
  3 and 4 - deep sleep/slow wave; in this stage it's difficult to wake someone up, this stage is associated with delta waves
  5 - final stage; REM or dream sleep, the body is paralysed (to stop the person acting out the dream) and brain activity ressembles that of an awake person
• on average a person can experience up to 5 full cycles in a night

Stern and Mclintock

• studied 29 women with irregular periods
• pheromones were taken from some at different stages of their cycle, via a cotton pad under their armpits
• these pads were cleaned with alcohol and later rubbed on the upper lips of the other participants
• 68% of the women's cycles got closer to that of their 'odour donor'
• demonstrated how menstrual cycles may synchronise as a result of the influence of female pheromones

structure of the brain

frontal lobe
parietal lobe
occipital lobe
temporal lobe

study by Campbell and Murphy

• fifteen participants were woken at various times and a light pad was shone on the back of their knees
• the researchers managed to produce a deviation in the participants' usual sleep/wake cycle of up to three hours in some cases
• this suggests that light is a powerful exogenous zeitgeber that does not necessarily rely on the eyes to exert its influence on the brain

summation

• the excitatory and inhibitory influences are summed (added together)
• if the net effect on the post synaptic neuron is inhibitory, the neuron will be less likely to 'fire'
• if the net effect on the post synaptic neuron is excitatory, the neuron will be more likely to 'fire'

sympathetic and parasympathetic nervous system

• two divisions of the autonomic nervous system
• often act in opposition to one another = antagonistic

sympathetic nervous system

• fight or flight

• ready for action

• dilates pupils

• accelerates heart

• constricts arteries

• relaxes bladder

synaptic transmission

• the relaying of information across the synapse by means of chemical neurotransmitters
• neurons communicate within neural networks
• each neuron is separated from the next by a synapse
• within the neurons signals are transmitted electrically
• between the neurons signals are transmitted chemically across the synapse
• when the electrical impulse reaches the end of the neuron (the presynaptic terminal) it triggers the release of neurotransmitter from tiny sacs called synaptic vesicles.
• once a neurotransmitter crosses the gap, it is taken up by a postsynaptic receptor site on the dendrites of the next neuron (axons take signals to the synapse, dendrites take signals away)
• here, the chemical message is converted back into an electrical impulse and the process of transmission begins again in the next neuron
• the direction of travel can only be one-way; this is because neurotransmitters are released from the presynaptic neuron terminal and received by the postsynaptic neuron (at the receptor sites)