Please enable JavaScript.

Coggle requires JavaScript to display documents.

Biopsychology - Coggle Diagram

- - - - the hypothalamus releases CRH into bloodstream
    - - the pituitary gland responds to CRH nd releases ACTH which is transported to the adrenal glands
    - - stimulates the adrenal cortex to release cortisol
      - Cortisol reduces sensitivity to pain and gives a quick burst of energy
      - special receptors in the hypothalamus and pituitary gland monitor circulating levels of cortisol releasing CRH and ACTH if levels rise above normal, bringing cortisol levels to normal
  - - - This involve protecting themselves and their young through nurturing behaviors (tending) and forming alliance with other women (befriend)
      - women’s responses evolved in the context of being the primary acregiver of the children, fleeing at any sign on danger would put the offspring at risk
      - this finding suggests that previous research which has mainly focused on males, has obscured the pattern sof stress in females
    - - Gray 1988 argues that the first phase of reaction to a threat is not to fight or flee but to avoid confrontation
      - this initial freeze response is essetianny a “stop look and listen” response where the animal is hyper-vigilant, alert to the slightest sign of danger
      - the adaptive advantage of this response is that freezing focuses attention and makes them look for new info in order to make the best response for that threat
    - - Von Dawans et al 2012 challenge the classic veiw that under stress men only respond with flight/fight and women respond with tend/befriend
      - this could explain why everyone was so nice to eachother in times of crisis like 9/11
      - this makes sense as human beings are fundamentally social animals and it is the protective nature of human social relationships that has allowed the species to thrive
    - - The SRY gene found exclusively on the male Y chromasome irects male development promoting aggression and resulting in the fight/flight response
      - the SRY geme may prime men to respond to stress in this way by the release of adrenaline and through increased blodd flow to organs involved in the fight/flight response
      - in contrast, the abscence of the SRY gene in females (who don’t have a Y chromosome) may prevent this response to stress, leading instead to tend/befriend behavior
- - - - Hughes 1977 tested the circadian hormone release in four Ps stationed at the British Antarctic Station
      - In febuary at the end of the antarctic summer corisol levels followed the familiar pattern- reaching their highest point as the Ps awoke and their lowest as the Ps went to bed
      - however, after 3 months of continuous darkness, this pattern had changed with the peak levels at noon rather than as they woke up
      - this suggests that the extremes of daylight found in polar regions of the world may be responsible for variations in circadian hormone release
      - however other research using scientific communities in the Artic who would be subject to similar prolonged winter darkness, found no such disruption of cortisol release
      - internal validity was compromised since only done on men
    - - chronotherapeutics- the study of how timing affects drug treatments
      - time medication is taken is very important as it can have a significant impact on the treatment success
      - essential that the right concentration is released in the target area at the time the drug is most needed
      - e.g heart attack risk is greatest during early morning hours after waking up
      - as a result, chronotherapeutics medications have been developed with a novel drug delivery system
      - these meds can be given before the indi go to sleep at 10pm but aren’t released until 6am-noon (Evans and Marain 1996)
    - - research suggests there are individual differences in circadian rhythms
      - one is the cycle length; research has found that circadian rhythms can vary from 13-6 hours (creisler et al 1999)
      - the other type of individual difference relates to cycle onset- idivs appear to be innately different in terms of when their circadian rhythms reach their peak
      - this (according to Duffy et al 2001) would explain why some people prefer to go to bed early/ wake up early or the opposite (early bird/night owl)
      - https://sleepsurge.com/morningness-eveningness-questionnaire/
    - - early research studies of circadian rhythms suffered from an important flaw when estimating the “free-running” cycle of the human circadian rhythm
      - in most studies, Ps were isolated from variables that might affect their rhythms such as clocks, radios or daylight
      - however, they were not isolated from artificial light because it was believed that dim artificial light wouldn’t affect their rhythms
      - research suggests that this may not be true as Czeiler at el 1999 altered Ps circadian rhythms down to 22 hours and up to 28 hours by using dim artificial lighting alone
      - suggesting that these early studies may have had confounding variables (artificial light)
    - - Buhr et al 2010 believe that is it a temperature that actually controls our body clock rather than light
      - although light may be the trigger the SCN transforms info about light levels into neural messages that set the body’s temperature
      - body temp fluctuates on a 24-hour rhythm
  - - - when we should sleep/ be awake
      - light and darkness are the external signals that determine when we feel the need to sleep and when to wake up
      - the circadian rhythm dips and rises at different times of the day soour strongest seep drive usually occurs in two dips
        
        between 2- 4am and 1-3 pm
      - the sleepiness during these dips is less intense if we have has sufficient sleep and more intense when we are sleep deprived
      - sleep and wakefulness are not determined by the circadian rhytm alone but are also under homeostatic control
      - when ur awake for a long time homeo stasis tells us that the need for sleep is oncreasing because of the amount of energy being used up during awakeness
      - this homeostatic drive for sleep increases gradually thorughout the day reaching it’s maximum in the evening when most poeple fall asleep
      - therefore the circadan rhytm keeps us awake as long as there is daylight prompting us to sleep as it becomes dark
      - the homeostatic system tend to make us sleepier as time goes on regardless of day or night
      - the internal circadian clock is described as free running i.e it will maintain a cycle of aout 24-25 hours even in the abscene of external cues
      - intolerant of any major alterations in sleep and wake schedules (e.e jet lag, night shift) since it will be thrown out of balance
  - - - first stay of 61 days in the southern alps in 1962
        
        resurfaced on 17th of september thinking it was august 20th
      - second stay 6 months in texas
        
        rhythm settled over just 24 hours but with some dramtic variations
      - final stay in 1999
        
        interested in rhytms over time
        
        he was 60 now
        
        found his body clock ticked slower comapred to when he was young
        
        sometimes streched to 48 hours
  - - - one of the best indicators of circadian rhythms
      - at it’s lowest at about 36C at about 4;30 am
      - highest at about 38C at about 6pm
      - sleep occurs when temp drops
      - temp rises during last hours of sleep promoting a feeling of alertness when you wake up
      - small drop in body temp also accur in most people between 2-4 pm which may explain why poeple feel sleepy in the afternoon
    - - hormone release follows a circadian rhythm
      - e.g production and release of melatonin from pineal gland in the brain follow a rhythm with peak levels occuring during the hours of darkness
      - by activating chemical receptors in the brain melotonin encourage feelings of sleep
      - when it’s dark more melotonin is produced
      - when it’s light the production of melotoin drops and the person wakes
- - - - responsible for the generatio nof voluntary motor movements
      - located in the frontal lobe in the precentral gyrus
      - both hemispheres have a motor cortex, with them controlling the opposites side’s movements (hemispheric lateralisation - the brain is bilateral)
      - different parts of the MC have controll over differnt body parts
      - these regions are arranged next to eachother (e.g foot region next to leg region)
    - - SSC detetcts sensory events arisng from different regions of the body
      - located in the parietal lobe in the postcentral gyrus
      - postcentral gyrus is dedicated to the processing of sensroy info related to touch
      - using sensory info fromthe skin, the SSC produces sensation of
        
        touch, pressure, pain and temperature
      - then localises the sense to the specific body region
      - both hemispheres have an SSC just like the MC
  - - - the primary visual centre is located in the Visual Cortex in the occipital lobe of the brain
      - however visual processing actually begins in the retina at the back of the eye where light enters and strikes the photoreceptors (rods and cones)
      - nerve impulses from the retina are then transmitted to the brain via the optic nerve
      - some impulses are involved in circadian rhythms
      - the majority terminate in the thalamus, which acts as a relay station passing the info onto the visual cortex
      - the VC spans both hemispheres with the right getting input from the left etc
      - the VC contains several different areas with each processing different types of visual info like colour/shape/movement
    - - the AC is is to do with hearing
      - cochlear in the inner ear —> auditory nerve —> brain stem (decodes the duration and intensity of a sound) —> thalamus (relay)—> Auditory cortex (recognised)
  - - - named Paul Broca who treated “Tan” (like the MeMe patient mum has)
      - Broca also studied 8 other patients with similar deficits along with damage to their left frontal hemisphere
      - patients with damage in the right hemisphere didn’t have the same language problems
      - this led to him identifying the existence of a “language centre” at the back of the left hemi frontal lobe
      - area believed to be critical for speech production
      - scientists found evidence of activity in the area while performing cognitive tasks that have nothing to do with language
      - Fedorenko et al (2012) discovered 2 regions of BA, one for language and one for demanding cognitive tasks (e.g math)
    - - Carl Wernicke
      - involved in understanding language
      - back of the temporal lobe
  - - - Expressive aphasia (Broca’s aphasia) is an impared ability to produce language- caused by damage to Broca’s area
      - Receptive aphasia( Wernicke’s aphasia) is impared ability to exract meaning from written or spoken words- result of damage in wernicke’s area
      - this demonstrated the different roles played by the brain regions in different aspects of language and that they are separate parts
    - - considerable variability in patterns of brain activation when reading, with activity in the right temporal lo;be as well as int the left frontal temporal and occipital
      - Harasty et al 1997; found women have proportionally larger Broca’s and Wernicke’s area than men
      - anatomical differences may explain superior language skills in girls
    - - Dronkers et al 2007; re-examined the preserved brains of two of Broca’s aphasic patients with MRI. Showed damage in other areas
        
        finding is significant because although damage to Broca’s area can cause tempory speech disruption they don’t usually result in severe disruption of spoken language
      - study suggests that language and cognition are more complicated than though and involve a network of areas rather than the specific ones
    - - Wernicke claimed that although each region has its own function, they are all interdependent and need to interact
      - e.g Joseph Dejerine 1892 described a case where the lost ability to read was due to damage to the connection between the visual cortex and wernicke’s area
      - suggest that complex behaviors like reading involve impulses being passed around different areas in the network of neurons
- - - - Morgan 1995 bred hamsters with abnormally short circadian shythms (20 hours) and transplanted some of their SCN neurons into normal hamster
      - Further confirmtion came in the reverse experiment when SCN neurons from normal hamster were transplanted into the abnormal hamsters- they then changed to a noraml 24 hour ciracadian pattern
      - supports importance of SCN in regulating 24 hour circadian rhytm
    - - toutou et al 2017; showed teens spent increasing amount of time on phones at night, LED bulbs had blue light
      - leads to impression of melatonin secretion and circadian disruption; so their sleep was irregular shortened and delayed
      - sleep deprivation can lead to increased heart conditions and mood disorders, so understanding of rhythms can be used to improve health
    - - sets the circadian rhythm; is demonstrated in studies of blind people
      - Skene and Arendt 2007; estimates most blind people have normally entrained circadian rhythms. people without light perception showed abnormal
      - suggest when the pathway from retinal cells containing melanopsin to the SCN is still intact light can still act as a zeitgeber
    - - Burgess eta l exposed volunteers to light treatment to shift sleep wake cycles; Ps sleep patterns and melatonin levels were monitored in a lab
      - Ps who were exposed to bright light fet sleepy 2 hours earlier in the evening and woke 2 hours earlier in the morning
      - shows circadian rhythms can be shifted by light exposure; useful for air travel
  - - - The most important zeitgeber for animals
      - Receptors in the SCN are sensitive to change in light level
      - use this info to synch the activity of organs and glands
      - light resets internal biological clock each day
      - rods and cones in retina of the eye detect light to form visual images
      - light detecting cell in the retina gauges overall brightness to rest clock
      - Melanopsin (sesntisitve to natural light) is critical
      - small number f retina cells contain melanopsin and carry signals to SCN to set to daily cycle
    - - Social stimuli such as mealtimes and activities may also have a role
      - Aschoff et al 1971 showed that indivs are able to compensate for the absence of zeitgebers such as natural light by responding to social zeitgebers instead
      - one of the early jet lag studies (Klein and Wegman 1974) found that the circadian rhythms of air travellers adjusted quicker if they went outside more at the destination
      - was thought to be because they were exposed to social cues of new time zone
      - cicradian rhytm of blind people were thought to be no different to sighted as both group were exposed to social cues
- - - - nerve impulses cross synapse between presynaptic and post synaptic neuron; helped by neurotransmitters
      - action potential arrives at the end of the axond and triggers the release of neurotransmitter molecules by exocytosis
      - NT molecules diffuse across the gap and bind to receptors in the membranes of post synaptic neuron; trigger new action potential
      - NT are removed from the synaptic gap by re uptake into synaptic neuron for recycling, or being broken down by enzymes
      - some drugs affect the reuptake/breakdown of NT e.g SSRis affect reuptake of serotonin
    - - Excitatory NT cause excitatory postsynaptic potential (EPSP); makes neuron more likely to fire. e.g acetylcholine and noradrenaline
      - Inhibitory NT causes an inhibitory postsynaptic potential (IPSP); makes neuron less likely to fire. e.g serotonin and GABA
      - NT have different effects when they bind to the receptor; total effect determines whether an impulse is produced in the next neuron
      - summation of IPSP and EPSP determines whether action potential is released
    - - Stimulus→receptor→sensory neuron→relay neuron→motor neuron→effector→response
      - neurons
        
        Neurons are specialised to carry neural information throughout the body
        
        Dendrites receive signals from other neurons
        
        From the cell body, impulses are arried along the axon where it terminates at the axon terminal
        
        Myelin sheath- insulating layer around the axon that allows nerve impulses to transmit faster. if it’s damged, impulses slow down.
        
        Length of a neuron can vary from a few mm to a m
        
        3 types
        
        Sensory
        
        Carry nerve impulses from sensory recptor to spinal cord and brain
        
        Sensory recptors found in places like eyes, ears, tounge, skin
        
        Sensort neurons convert info into neural impulses
        
        When the impules reach the brain they’re translated into sensations e.g visual input, heat, pain etc so the organism can react approriately
        
        Not all info goes to the brain, some terminate in the spinal cord allowing relex actions to occur quickly without delay of impuses
        
        Relay
        
        Most neurons are neither sensory nor motor but lie between the sensory input and the motor output
        
        allow sensory and motor neurons to communicate
        
        Lie wholly within the brain and spinal cord
        
        Motor
        
        Neurons that conduct signals from the CNS to effector organs like muscles
        
        Cell bodies in the CNS but long axons part of the PNS
        
        Form synapses with muscles and control their contractions
        
        when stimulated MN release neurotransmitters that bind to recptors on the muscle and triggers a response leading to muscle movement
        
        when the axon of a MN fires the muscle with a synapse contracts
        
        the strength of the muscle contraction depends on the rate of firing of the axons of motor neurons that control it
        
        muscle relaxation is caused by inhibition of the motor neuron
  - - - Consists of all other nerves in the body
      - Made of 2 parts
        
        Autonomic NS
        
        controls involuntary movement
        
        Made of 2 parts
        
        sympathetic
        
        fight or flight
        
        noradrenaline; increases heart rate, dilates blood vessels and pupils, slows non emergency function e.g digestion
        
        Parasympathetic
        
        rest and digest
        
        Acetylcholine; slows heartbeat, reduces blood pressure, restores non emergency functions like digestion
        
        Somatic NS
        
        sensory neurons
        
        motor neurons
    - - Spinal cord
        
        Function- relays info between brain and rest of the body
        
        allows the brain to regulate bodily processes like digestion and breathing and to coordinate voluntary movements
        
        connected to different parts by pairs of spinal nerves that connect specific muscles and glands
        
        e.g spinal nerves that branch off the thoratic region carry messages to and from the chest and parts of the abdomen
        
        also contains circuits of nerve cells enabling simple reflexes without direct brain involvement; e.g pulling hand away from hot thing
        
        If damaged, areas below will be cut off by the brain and stop functioning
      - Brain
        
        Brain Stem (turqoise)
        
        regulates automatic functions
        
        e.g breathing, heartbeat and swollowing
        
        motor and sensory neurons travel through brain stem allowing impulses to pass between the brain and spinal cord
        
        Cerebellum (red)
        
        sits beneath the back of cerebrum
        
        controls motor skills and balance, coordinating muscles to allow precise movements
        
        abnormalilites of this area can result in problems including speech/motor issues and epilepsy
        
        Cerebrum (yellow)
        
        largest part
        
        4 lobes
        
        Frotal lobe: speech, thought and learning
        
        Parietal lobe: process sensory info like touch, teperature and pain
        
        Occipital lobe: visual info
        
        Temporal lobe: hearing and memory
        
        Split into two halves (cerebral hemispheres) and specialised for particular behaviors as the two halves communicate with eachother through the corpus callosum
        
        Dienchephalon (purple)
        
        Two areas within: thalamus and hypothalamus
        
        Thalamus
        
        relay station for nerve impulses coming from the senses and routing them to the appropriate part of the brain where they can be processed
        
        Hypothalamus
        
        Regulation of body temperature, hunger and thirst
        
        Acts as the link between the endocrine system and the nervous system
        
        Controls release of hormones from the pituitary gland
        
        below the cerebrum and on top the brain stem
- - - - they are relesed by endocrine glands in the bloodstream where there circulate around the whole body
      - they bind to specific receptor molecules on the surface of target cells, stimulating a reponse in the target cells
  - - - controlled by the hypothalamus
      - regulates many body functions
      - releases hormones which control many other endocrine galnds
      - Anterior pituitary
        
        releases adrenocortocotrophic hormone (ACTH) as a response to stress
        
        also produces lutenising hormone (LH) and follicle stimulating hormone (FSH)
      - Pituitary hormones in men/women
        
        in females LH and FSH stimulate the ovaries to reduce oestrogen and progesterone
        
        in men they make the spermies
      - the posterior pituitary
        
        releases oxytocin
        
        in women stimulates conractions and involved in mother-infant bonding
        
        in men plays a role in sexual behavior and reduces anxiety
    - - on top of the kidneys
      - adrenal cortex produces cortisol
      - regulates important cardiovascular functions in the body
      - the adrena medulla releases adrenaline and noradrenaline which prepares for flight or fight
      - Cortisol production
        
        increased in reponse to stress
        
        if low the indiv has low blood pressure poor immune function and an inibility to deal with stress
      - Adrenaline
        
        responds to acute stress
        
        increases heartrate and blood flow to the muscles and brain
        
        encourages the breakdown of glycogen into glucose to provide energy
      - Noradrenaline
        
        constricts the blood vessels causing blood pressure to increase
  - - - this stimulates the pituitary to release adrenocorticotrophic hormone (ACTH)
      - this stimulates the release of hormones from the adrenal cortex such as cortisol
      - and increase in the blood concentration of cortisol slows down the release of CRH and ACTH
      - this ensures levels or hormones circulating in the blood are kept stable
  - - - the hypothalamus and pituitary gland have special receptors that monitor circulating cortisol levels
      - monitoring and controlling cortisol levels limit the potentially damaging effect of this hormone on the body
      - however, research has found that the longer an indiv is exposed to stress the more adverse the effects are
      - this may explain why indivs in stressful jobs and such experience more stress-related illnesses
- - - - seen in variations in mood (seasonal depression)
      - increased rates of heart attacks in winter
      - peak of deaths in January
    - - changes in hormone levels and blood pressure at weekends
    - - internally governed
      - vary between 23 and 36 days but averages 28
      - regulated by hormones
      - ovulation takes place roughly halfway through the cycle
  - - - Tucker et al 2007 studied Ps over 11 days and nights in a sleep lab
      - They assessed sleep duration, time to fall asleep and the amount of time in each sleep stage
      - found large consistent individual differences in each of these characteristics, for deep sleep, the individual differences were particularly significant
      - this meant that differences between individuals may not be caused just by circumstances but are at least partially biologically determined
    - - Ericsson et al 2006 found that elite violinists generally practice for no more than 90 minutes at a time but several times a day
      - the violinists frequently napped Russellver from practice with the very best violinists napping more than their teachers
      - consistent with the predictions of the BRAC Erthem Ericsson research other same pattern among other musicians athletes, chess players and writers
    - - when several women of childbearing age live together and don’t take the pill their menstrual cycles tend to sync
      - russell et al 1980 applied daily samples of sweat from one group of women onto the upper lips of women in a different group and kept away from eachother
      - their menstrual cycles ended up syncing
      - this suggests that a women’s menstrual cycle can be affected by pheromones from other women as well as their own pituitary hormones
    - - women generally prefer slightly feminised faces representing kindness and compassion when picking long-term relationships
      - however, around ovulation women showed a preference for more masculine faces representing ‘good genes’ for short-term liaisons with more likelihood of conception
      - this shows how hormonally controlled rhythms may also imact behaviour
- - - - measures changes in blood oxygenation and flow indicating increased neural activity in particular brain area
      - useful for identifying which areas of the brain are involved in particular mental activities
    - - measure electrical activity in the brain via electrodes placed on the scalp
      - show brainwaves over time
      - EEG pattterns in epilepsy patints show spikes of elctrical activty
      - Alzheimer’s patients often show overall slowing of electrical activity
    - - very small voltage changes triggered by specific stimuli or cognitive events
      - sensory ERPs occure in the first 100 milliseconds after the stimulus is presented; cognitive ERPs are generated later and demonstrate information processing
      - use statistical averaging to eliminate noise of the brain so is the only one that has any causation
  - - - fMRI offeres a more objective and reliable measure of psychological processes than is possible with verbal reports
      - however, fMRI measures changes in blood flow in the brain so it is not a direct measure of neural activity in particular brain areas
      - Critics also argue that fMRI overlooks the networked nature of brain activtiy as it focuses only on localised activity on the brain
    - - One strength of the EEG technique is that ot provides a recording of the brain’s activity in real time rather than an image of a passive brain
      - However, EEG can only detect the activity in superficial brain regions so it cannot reveal what is going on in the deeper regions such as the hypothalamus or hippocampus
      - Also neighbouring electrodes pick up electrical activity from overlapping areas aso EEG can’t pinpoint the exact source of activity
    - - An ERP can measure te processing of stimuli even i nthe abscence of abehavioral response making it possible to monitor brain processes without requiring th person to respond verbally
      - However, ERPs are very small and difficult to pick out from other elctrical activity in the brain so it make tak e a few trail to get meaningfull results
      - Another limitation of the ERP technique is that electrical activivtes occuring deep in the brain aren’t recorded
    - - E.g post-motem studies of the brain have enabled researchers to discover structural abnormalities and neurochemical changes in schizophrenia
      - however, diverse causes of death, suse of drugs and age at death may affect the brain tissure so there may be confounding variables
      - Another problem is that data can only be collected retrospectively when it is too late to test hypotheses about cognitive function realting to abnormalities
- - - - Sperry and Gazzaniga’s 1967
      - quasi experiment
      - to test the capabilities of separated hemispheres they were able to send visual nfo to just one hemisphere at a time to study hemispheric lateralisation
      - They took adventage of the fact that info presented to the left goes to the right and vice versa
      - because the corpus callosum is cut with split-brain patients the infor presented in one side has no way of getting to the other and can be only processed in the hemisphere that receives the info
      - in a typical test the patient would fixate on a dot in the center of a screen whilst the info was presented on either the left or right side
        
        they would then be asked to make responsess with teither their left or right hand
        
        severed corpus callosum video
      - this has lead to the conclusion that left is for language and right is for visual-motor stuff
    - - Lateralisation is related to increased neural processing capacity
        
        by only using one hemisphere to engage in a particular task (e.g language/math problems), would leave the other hemisphere free to engage in another function
        
        dolphins sleep with one eye open and half their brain awake, this is so they can rest whilst also being able to go up to the surface to breathe
        
        this finding provides some evidence that brain lateralisation enhances brain efficiency in cognitive tasks that demand the simultaneous but different use of both hemispheres
      - Lateralisation changes with age
        
        lateralised patterns found in younger indivs tend to switch to bilateral patterns in healthy older adults
        
        for example Szaflarski 2006 found that language became more lateralised to the left hemisphere with increasing age in children but after 25 it decreased every year
        
        may be because using the extra processing resources of the other hemisphere may compensate for age-related declines in function
      - Some findings of early split-brain research have been disconfirmed more recently
        
        a major claim of split-brain research was that damage to the left hemisphere leads to a loss of language function
        
        however case studies have demsotrated that this wasn’t necessarily the case; J.W developed to capacity to speak about info presented to the left or the right brain
        
        challenges the claim that the right hemisphere is unable to handle language
      - Limitations of split-brain research
        
        split brain procedure is rarely carried out and many studies only involve a few or one patient
        
        these patients may have had underlying physical disorders that made the split brain procedure necessary or there may have been some intact nerve fibers remaining
        
        mean the results of studies are not always replicated and may be unwise to draw any conclusions as you can’t generalise the findings
    - - Lateralisation- the fact that the two halves of the human brain are not exactly alike
      - Each hemisphere has functional specialisations i.e neural mechanisms for some functions are localised primarily in one half of the brain
      - For example the left hemisphere is dominant for language and speech
      - the right has visual - motor tasks
      - in 1861 Paul Broca established that damage in a partcular area of the left hemisphere led to language issues yet damage in the same area on the right side didn’t have the same consequcence
      - the hemispheres are connected
        
        this allows info to be sent from one hemisphere and sent to the other through nerves fibre bundles like the corpus callosum
      - Cut the corpus callosum as a treatment for severe epilepsy
        the aim was to prevent the violent electrical activity that accompanies epileptic seizures crossing from one hemisphere to the other
        
        patients who underwent this form of surgery are often referred to as split-brain patients
  - - - For example, playing video games results in new synaptic connections in brain areas involved in spatial recognition, strategic planning, working memory and motor performance
      - there is a gradual decline in cognitive function with age but even 60-year olds still have brain plasticity and can increase their gray matter in the visual cortex whe taught a new skill such as juggling
      - Davidson et al (2004) found that experienced meditations (Tibetan monks) produced more gamma brainwaves that student volunteers, indicating that meditation causes permanent change
    - - When brain cells are damaged, as they are during a stroke, other parts sometimes take over their functions
      - This can heppen by neural unmasking in which dormant synapses can be reactivated when they receive more neural input than previously
      - stem cells implanted into the brain may help to treat brain damage, by directly replacing damaged cells
      - stem cells secrete growth factors that ‘rescue’ injured cells, or they form a neural network linking areas with the damaged brain region
    - - In rats, an enriched environment increases the number of neurons in the brain
        
        Kempermann et al 1998 found that rats housed in complex environments developed more neurons than rats housed in lab cages
        
        In particuar, they showed an increase in neurons in the hippocampus, which is associated with the formation of new memories and the ability to navigate
        
        This shows clear evidence of the brain’s ability to change as a result of exxperience
        
        can’t generalise from animal studies
        
        high internal validity
      - Research support from a study of taxi drivers
        
        Maguire et al 2000 discovered that changes in the brain could be detected as a result of taxi drivers extensive experience of spatial navigation
        
        MRI scansshowed that the posatieior hippocampi of the drivers was significantly larger the the control patients. The volume positively correlated with the amout of time the driver had been a driver
        
        this shows that the highest levels of plasticity were evident in those with more extensive experience
      - Age differences in functional recovery
        
        it is a commonly accepted veiw that functional plasticity reduces with age and adults with trauma require social support or must develop strategeies to deal with cogitive deficits
        
        however studies have suggested that even abilities thought to be fixed in childhood can stilll be modified in adults with intense retraining
        
        the capacity for neural reorganisation is still much greater in children than in adults as demonstrated by the great amount of practice that adults require to produce changes
      - Educational attainment and functional recovery
        
        A retrospective study by Schneider et al 2014 examined data on traumatic brain injuries (TBI) from a US TBI database
        
        this showed that nearly 40% of patients with a college level education acheived disability free recovery after a year, compared to less than 10% of patients who left school early
        
        the researcher concluded that cognitive reserve (associated with greater educational attainment) was an important factor in neural adaptation during recovery from traumatic brain injury