essay plans Flashcards
neurons
What is a neuron - the basic building blocks of the nervous system, neurons are nerve cells that process and transmit messages through electrical and chemical signals
Sensory neurons - these carry messages from the PNS to the CNS. They have long dendrites and short axons
Relay neurons - these connect the sensory neurons to the motor or other relay neurons. They have short dendrites and short axons
Motor neurons - these connect the CNS to effectors such as muscles and glands. They have short dendrites and long axons
Exitation - when a neurotransmitter, such as adrenaline increases the positive charge of the postsynaptic neuron. This increases the likelihood that the postsynaptic neuron will pass on the electrical impulse.
Inhibition - when a neurotransmitter, such as serotonin, increases the negative charge of the postsynaptic neuron. This decreases the likelihood that the postsynaptic neuron will pass on the electrical impulse.
Electrical transmission
- When resting - negatively charged compared to outside
- When activated by stimulus - inside the cell becomes positively charged for a split second causing an action potential to occur - creates an electrical impulse that travels down the axon towards the end of the neuron
Chemical transmission
- Neural networks - neurons communicate with eachother within groups
- Signals between neurons are transmitted chemically across the synapse
- Electrical impulse reaches the end of the neuron (presynaptic terminal) - triggers the release of neurotransmitter from synaptic vesicles
Neurotransmitters
- Chemicals that diffuse across the synapse to the next neuron in the chain
- Taken up by postsynaptic receptor site on dendrites
- Several dozen types of neurotransmitter have been identified
- Acetylcholine found at each point where a motor neuron meets a muscle
Summation -
process that decides whether a postsynaptic neuron fires
- Excitatory and inhibitory influences are summed - if net effect on the postsynaptic neuron is inhibitory then the postsynaptic neuron is less likely to fire
the nervous system
The nervous system - specialised network of cells - central nervous system and peripheral nervous system
communicates using electrical signals
collect, process and respond to information
co-ordinate the working of different organs and cells
Central nervous system - consists of brain and spinal cord
origin of all complex commands and decisions
Peripheral nervous system - sends information to the CNS from outside world and transmits messages from CNS to muscles and glands
Somatic nervous system - transmits information from receptor cells in the sense organs to the CNS - receives information from the CNS that directs muscles to act
Autonomic nervous system - contains sympathetic and parasympathetic - transmits information to and from internal bodily organs
Endocrine system - body’s major information systems that instructs glads to release hormones directly into the bloodstream - hormones carries towards target organs in the body
Glands - an organ in the body that synthesises substances such as hormones eg pituitary, thyroid, adrenals
Hormones - chemical substances that circulate in the bloodstream and only affect target organs, produced in large quantities but disappear quickly
fight or flight AO1
What is fight or flight - The way an animal responds when stressed - becomes physiologically aroused in readiness to fight or flee
Adrenaline - From the adrenal medulla - part of adrenal glad near kidneys - Triggers physiological changes in body - fight or flight response
Sympathetic state -
Sympathetic NS prepares the body for action
- increases heart rate
- Increases breathing rate
- Dilates pupils
- Inhibits digestion
- Inhibits saliva production
- Contracts rectum
Parasympathetic state -
Parasympathetic brings the body back to its resting state
- Decreases heart rate
- Decreases breathing rate
- Constricts pupils
- Stimulates digestion
- Stimulates saliva production
- Relaxes rectum
Steps
1. The amygdala reacts to threat
2. The hypothalamus activates the sympathetic nervous system, release of adrenaline
3. The adrenal cortex releases cortisol for continued alertness
The hypothalamus activates the sympathetic branch of the autonomic nervous system
The adrenal glands respond by pumping adrenaline into the bloodstream, as this circulates through the body, it brings on a number of physiological changes
The heart beats faster than normal, pushing blood to the muscles, heart and other vital organs
Airways in the lungs open wide so that the lungs can take in as much oxygen as possible with each breath
Pupils dilate so that we can see more clearly; unessential systems such as digestion are also inhibited; blood is shunted away from the stomach to the major muscle groups where it will be used during an emergency
Once the threat passes the parasympathetic nervous system returns body to its resting state
fight or flight AO3
Critique
P - may have been useful for ancestors - less relevant now in modern day life
E - stressors in modern day life trigger fight or flight - bad for our health
E - stress and continually activate the sympathetic nervous system increase blood pressure which can cause damage to their blood vessels and heart disease
L - suggests fight or flight response is a maladaptive response in modern-day life
Opposing research - Taylor
P - reflection is bias towards male physiology
E - female fight or flight - risk for her children - leaves them vulnerable
E - Taylor 2006 - ‘tend and befriend’ - women more likely to protect their offspring and form alliances with other women
L - fight or flight is subject to beta bias
Different explanation - Lazarus
P - Psychological factors - cognitive appraisal is ignored
E - Lazarus - 1999 - we make appraisals of stress by actively working out if it is a threat and whether we have the resources to cope with it
E - med students response to watching a procedure on film was determined by whether they believed the procedure to be traumatic (increased heart rate) or a rite of passage (decreased heart rate)
L - difficult for purely physiological explanations to account for this findings, this therefore shows that humans are not just passive in the face of stresses
localised functions of the brain AO1
Brain structure
front - frontal lobe
top - parietal lobe
bottom - temporal lobe
back - occipital lobe
Motor area - at the top within the frontal lobe - controls voluntary movement in the opposite side of the body
Broca’s area - in frontal lobe near the ear - mostly found in left hemisphere - responsible for speech production - if area is damaged - patients struggle to speak fluently (broca’s aphasia)
Auditory area - temporal lobe, near ear, under broca’s - processes speech based information
Wernicke’s area - middle of the temporal lobe - left hemisphere mostly - damage results in being able to speak however words lack meaning - problems understanding it
Cerrebellum - next to spinal cord under occipital lobe
Visual area - in the occipital lobe - receives visual information from each eye - the left visual field will be processed in the right hemisphere and vice versa
Somatosensory centre - top middle of brain in parietal lobe - sensory information from the skin is processed here
What is localisation of function- the idea that certain functions have certain locations or areas within the brain
Holistic approach -
in early 19th C - supported in holistic theory that all parts of brain involved in processing thought
now localisation theory
localised functions of the brain AO3
Evidence from neurosurgery
P - strength is damage to areas linked to mental disorders
E - neurosurgery - last resort method for treating some mental disorders - targeting specific areas of brain may be involved
E - cingulotomy - isolating region called cingulate gyrus implicated in OCD - Dougherty et al - 44 people with OCD who underwent cingulotomy and saw that in post-surgical follow-up after 32 - 30% had met criteria for successful response and 14% partial response
L - success suggests behaviours associated with serious mental disorders may be localised
Evidence from brain scans
P - Brain scans support idea that everyday brain function is localised
E - Petersen et al - brain scans demonstrate how Wernicke’s area active during a listening task and Broca’s during a reading task
E - LTM by Buckner and Peterson revealed semantic and episodic memories reside in different parts of the prefrontal cortex - localised areas
L - objective methods of measuring brain activity provide sound scientific evidence that brain functions localised
Counterpoint
P - a challenge to localisation theory from Lashley
E - Lashley removed areas of cortex (10-50%) in rats that were learning a route through a maze
E - no area was provide more important - process of learning seemed to require every part of cortex rather than being confined to one area
L - suggests that higher cognitive processes, eg learning, not localised but distributed in a more holistic wag
Language localisation questioned
P - limitation as language may not be localised to just Broca’s or Wernicke’s area
E - Dick and Tremblay - recent review - only 2% of modern researchers think language in brain is completely controlled by broca’s and wernicke’s area
E - advances in imaging techniques eg fMRI - neural processes studied in more clarity and language function distributed far more holistically - even identified across the cortex and subcortical regions eg thamalus
L - rather than being confined to a couple of key areas, language may be organised more holistically in the brain, contradicts localisation theory
Phineas Gage - pole in head - change in personality - calm to quick tempered and rude
hemispheric lateralisation AO1
Hemispheric Lateralisation - The idea that the hemispheres are functionally different, each controlling certain mental processes and behaviours that the other doesn’t
Split-brain research - Studies which began in 1960s involving people with epilepsy who have experienced a surgical separation of the hemispheres
Left hemisphere - Language areas in LH, is the analyser
Right hemisphere - RH is the synthesiser
Contralateral - In both hemispheres, eg motor areas, visual areas, LVF, auditory areas
Sperry procedure - 11 participants, split-brain operation for epilepsy
Sperry findings -
Participant shown object in RVF (LH), able to describe object, when shown in LVF, says nothing there
Object shown in LVF, cannot name but select item with left hand
Pinup picture to LVF - participant giggles but reports nothing
Sperry conclusions - Lateralised brain, LH verbal and RH ‘silent’ but emotional
hemispheric lateralisation AO3
Lateralisation in the connected brain - Fink et al
P - strength - research - even in connected brains - two hemispheres process information different
E - PET scans - identify which brain areas active during visual processing task
E - when participants with connected brains asked to attend global elements of image - regions of RH more active - focus on finer detail then LH
L - hemispheric lateralisation feature of the connected brain as well as split
One brain - Neilsen et al
P - idea that Lh as analyser and Rh as synthesiser wrong
E - different functions in RH and LH - people do not have dominant side
E - brain scans - 1000 people - did not find people used certain hemispheres for certain tasks - no evidence of dominant side
L - notion of light or light brained is wrong
Lateralisation versus Plasticity - Rogers et al
P - lateralisation adaptive as enables two tasks performed simultaneously
E - Rogers et al - lateralised chickens - find food while watching predators - normal chickens couldnt
E - HOWEVER - neural plasticity - adaptive - some functions can be taken over by non-specific areas
L - eg language function can switch sides
Sperry generalisation
P - limitation of Sperry’s research - causal relationships hard to establish
E - Sperry’s split-brain participants compared to neurotypical control group
E - non of participants in control had epilepsy - confounding variable - results may be due to epilepsy
L - some of the unique features might be due to their epilepsy
Sperry research support - Luck et al, Kingstone et al
P - strength is more recent split-brain research
E - Luck et al - split-brain participants perform better than connected controls on certain tasks eg faster at identifying odd one out from similar objects
E - Kingstone et al - in the normal brain LH better cognitive strategies held back by RH
L - supports Sperry’s earlier findings that hemispheres are distinct
Opposing research - Jodie Miller
Real life case-studies - Jodie Miller - hemispherectomy - fails to explain her lack of visuo-motor problems - lateralisation is not fixed, the brain can adapt to new requirements
Controlled
Controlled setting with standardised procedures - image flashed for 1/10th of a second so patient couldn’t move eyes across to image - conclusions are genuine
Ecological validity and mundane realism
Artificial tasks such as composite words - lack mundane realism
Everyday life a severed corpus callosum - compensated fr by unrestricted use of two eyes - setting lacks ecological validity
Unsure the left and right hemisphere works according to lateralisation theory in real-life situations
plasticity AO1
Neuroplasticity - The reorganisation of neurons and neuronal pathways in the brain - involves the generation of new neurons, new connects between pre-existing neurons and the deletion of disused neurons
Functional recovery - Neuroplasticity in response to brain trauma, eg, through stoke or physical injury, which compensates for lost function
Stages of neuroplasticity -
1. Rapid growth slows at 2-3
2. From birth to 2, 40,000 synapses a second
3. Late adolescence, nearly 50% of synapses eliminated
4. thought to be static - disproven in 1998
5. Happens at any time in life due to experience
Meditation study - Holzel et al - 2011 - individuals who took part in a 8 week mindfulness-based stress reduction course showed an increase in grey matter in the left hippocampus - learning and memory
Supporting evidence -
Eleanor Maguire - 2000 - London taxi drivers - larger posterior hippocampi
- Positive correlation between time spent as a taxi driver and volume of hippocampi
After brain trauma - Brain often able to adapt and compensate for areas damaged - functional recovery may occur - healthy brain areas may take over functions
Axonal sprouting - The growth of new nerve endings connect to undamaged nerve cells to form new neuronal pathways
Denervation super-sensitivity -
Axons that do a similar job become aroused to a higher level to compensate for ones that are lost
- Negative consequence of oversensitivity to messages such as pain
Recruitment of homologous areas on opposite side of brain -
Specific tasks can still be performed
- Broca’s area on left side damaged - right side equivalent would carry out functions
Functional recovery after trauma - Spontaneous recovery - true healing - happens within the first few months then slows down
Rehabilitation therapy to encourage neuroplasticity -
- Recruiting undamaged parts of brain to perform a function previously performed by a different area
Constraint induced manual theory - unaffected limb is constrained so the patient is forced to use the affected limb
plasticity AO3
Negative plasticity
Limitation - may have negative behavioural consequences
- Brain’s adaptation to prolonged drug use - poorer cognitive functioning in later life and increased risk of dementia
- 60-80% of amputees - phantom limb syndrome
- Unpleasant, painful - due to cortical reorganisation in the somatosensory cortex
Suggests that the brain’s ability to adapt to damage is not always beneficial
Age and plasticity - Bezzola
Strength - life-long ability
- Reduces with age
- Ladina Bezzola et al - 2012 - 40 hours of golf training produced changes in neural representations of movement in participants aged 40-60
- fMRI - observed increased motor cortex activity in novice golfers compared to control - more efficient neural representations
- Neural plasticity can continue thoughtout the lifespan
Seasonal brain changes
Research - seasonal plasticity
- Suprachiasmatic nucleus - regulates sleep - particular brain shrinks in animals during spring and expands throughout autumn
- Much of the work on seasonal plasticity has been done on animals, songbirds
- Human behaviour may be controlled differently
Real world application
Strength - functional recovery
- Contributed to field of neuroehabilitation
- Encourages new therapies
- Eg constraint-induced movement
- Research into functional recovery is useful as it helps medical professionals know when interventions need to be made
Cognitive research - Schneider et al
Limitation - level of education may influence recovery rates
- Eric Schneider et al - 2014 - more time people with brain injury spent in education - greater chances of disability-free recovery
- 40% of those who achieved DFR - more than 16 years education compared to 10% who has less than 12 years education
- Implies that people with brain damage who have insufficient DFR are less likely to achieve a full recovery
studying brain AO1
Functional magnetic resonance imaging -
Measure brain activity while person is performing task
- Detects radio waves from changing magnetic fields
- Detect regions of brain that are active
Three-dimensional images showing which parts of the brain are involved in a particular mental process - important for localisation of function
Electroencephalogram -
Record of tiny electrical impulses produced
- EGG can help diagnose certain conditions of the brain
Often used by clinicians - diagnostic tool - unusual arrhythmic patterns indicate neurological abnormalities
Statistical averaging technique - filters out extraneous brain activity
- What remains are event-related potentials
Event-related potentials - Electrophysiological response of the brain to specific sensory, cognitive or motor event - isolated through statistical analysis of EEG data
Post-mortem examinations -
Brain analysed after death
- Determines whether certain observed behaviour were linked to structural abnormalities in the brain
What is scanning used for -
Medical purposes in diagnosis of illness
Investigate localisation
studying brain AO3
A lot of strengths as limitations for each
fMRI 4, 3
- Does not rely on radiation
- Produces images that have very high spatial resolution
- Virtually risk-free, non-invasive and straightforward
- Non-invasive - doesn’t involve radiation or inserting anything - allows more people to take scans
- Expensive compared to other techniques
- Poor temporal resolution - 5-second time-lag
- Not truly represent moment-to-moment brain activity
EEG 3, 3
- Useful in studying stages of sleep and in diagnosis of conditions such as epilepsy
- Extremely high temporal resolution
- Real-world usefulness
- Generalised nature of information received
- May not be useful for pinpointing the exact source of neural activity
- Does not allow researcher to distinguish between activities originating in different but adjacent locations
ERP 3, 3
- Bring more specificity to measurement of neural processes than raw EEG data
- Excellent temporal resolution - EEG data
- Used to measure cognitive functions and deficits such as allocation of attentional resources and the maintenance of working memory
- Lack of standardisation in ERP methodology between different research studies
- Difficult to confirm findings
- Pure data in ERP studies - background noise and extraneous material must be completely eliminated - not always easy
Post 3, 2
- Vital in providing foundation for early understanding of key processes in the brain
- Broca and Wernicke - relied - establishing links between language, brain and behaviour
- Used to study HM’s brain
- Observed damage to brain may not be linked to the deficits under review but to some other unrelated trauma or decay
- Ethical issues - may not be able to provide informed consent eg HM lost ability to form memories
circadian rhythms AO1
Biological rhythms - Controlled by internal body clocks (endogenous pacemakers) and external cues (exogenous zeitgabers) - cyclical time periods
Circadian rhythms - Biological rhythms - subject to a 24-hour cycle - regulate a number of body processes such as the sleep/wake cycle and changes in core body temp
Endogenous pacemakers - Body’s internal biological clock
Exogenous zeitgebers - Changes in the environment
Sleep/wake cycle - Governed by daylight and by biological clock (suprachiasmatic nucleus), get light information from the eyes
Siffre’s cave study -
- Extended periods undergroup - effects of own biological rhythms
- Free-running rhythm extended slightly to 25 hours when deprived of daylight
Aschoff and Wever -
- Group of participants - 4 weeks in ww2 bunker - no natural light
- Between 24 and 25 hour cycle
Simon Folkard et al -
- Group of 12 people - live in dark cave for 3 weeks
- Went to bed at 11.45, rising at 7.45
- Sped clock gradually - only 22 hours
- Only one of participants was able to comfortably adjust
circadian rhythms AO3
Shift work
P - strength is provides understanding of consequences when disrupted (desynchronisation)
E - night workers engaged in shift work experience a period of reduced concentration around 6 in morning so more mistakes and accidents likely
E - research saw relationship between shift work and poor health - more likely to develop heart disease than those with typical work
L - research into sleep/wake cycle may provide real-world economic implications in terms of how best to manage worker productivity
+ counterpoint
P - studies investigating the effects of shift work tend to use correlation methods
E - difficult to establish whether desynchronisation of sleep/wake cycle actually a cause of negative effects
E - Solomon - high divorce rates in shift workers might be due to strain of deprived sleep and other influences such as missing out on important events
L - suggests may not be biological factors that create the adverse consequences associated with shift work
Medical treatment
P - strength of research into circadian rhythms is that is has been used to improve medical treatments
E - circadian rhythms co-ordinate number of body’s basic processes eg heart rate, digestion and hormone levels
E- rise and fall during the course of day - led to field of chronotherapeutics - how medical treatment can be administered in a way that corresponds to biological rhythms eg aspirin reduces heart attack risk and heart attacks most common in the morning
L - circadian rhythm research can help increase the effectiveness of drug treatments
Individual differences
P - limitation to research into circadian rhythms is generalisations are difficult
E- studies based on small samples and sleep/wake cycles vary from person to person
E- Czeisler found individual’s sleep/wake cycles varying from 13 to 65 hours and Duffy saw some people have reference to morning - early risers - larks and owls
L - difficult to use the research data to discuss anything more than averages, which me be meaningless
infradian and ultradian rhythms AO1
Infradian rhythm - A type of biological rhythm with a frequency of less than one cycle in 24 hours, such as menstruation and seasonal affective disorder
Ultradian rhythm - A type of biological rhythm with a frequency of more than one cycle in 24 hours, such as the stages of sleep (the sleep cycle)
Menstrual cycle - Oestrogen regulates ovulation, progesterone readies body for pregnancy (endogenous factors)
Synchronising the menstrual cycle - Menstrual cycles synchronised through pheromones, exogenous factor (stern and McClintock)
Stern and McClintock -
Menstrual cycles may synchronise as a result of the influence of pheromones
- 29 women with a history of irregular periods
- Pheromones gathered from 9 at different stage of cycle
- Rubbed on upper lip of other participants
- On day one, pads from the start of the menstrual cycle were applied to all 20 women, on day two they were given a pad from the second day of the cycle and so on
- 68% of women experienced changes to their cycle - brought them close to the cycle of their odour donor
Ultradian rhythm example - stages of sleep
Stages of sleep -
5 stages - 90 min cycle
- 1 and 2 - alpha waves and sleep spindles
- 3 and 4 - deep sleep, delta waves
- REM sleep, theta waves
Seasonal affective disorder - Form of depression triggered in the winter months and regulated by melatonin, circandian rhythm
