paper 2 Flashcards
plasticity
- Plasticity is the tendency of the brain to change and adapt due to experience and learning
-peaks of 15000 new connections i infants which is 2x of an adult brain
-synaptic pruning = as we age the rarely used connections disappear and frequently used ones get stronger
-Maguire > taxi drivers> more grey matter in posterior hippocampus compared to control group> associated with navigational and spatial skills> retake knowledge test > assess recall of routes> longer in job the more structural differences
-dragonski > brain studied of med students 3 months before and after final exam > changes in posterior hippocampus
+ plasticity may be a life long ability > 40 hrs of golf training produced changes in neural representations in movement in ppt aged 40-60>using fmri he found increased motor cortex activity in golfers and compared to control group suggesting more efficient neural representations after training > neural plasticity can continue throughout life
——Seasonal brain changes in response to environmental changes > scn regulates s/w cycle . evidence that this particular bran structure shrinks in all animals during spring and expands throughout autumn
functional recovery of brain after trauma
-brains ability to redistribute functions usually performed by damaged area to other undamaged areas
-healthy areas of brain take over functions of damaged one
-redistribution can occur quickly after trauma but slow down after several weeks > so rehab may needed to aid recovery
-brain rewires and reorganises itself by making new synaptic connections
-neural pathways that wont normally be used carry out certain function are activated (unmasked) to allow normal functioning as before
-axonal sprouting = new nerve ending growth with undamaged nerves to form new neural pathways
-denervation supersensitivity > neurones with similar function become aroused and compensate for lost
-recruitment of homologous areas of opposite side of brain - eg brocas area is LH damaged the RH takes over
+real world application > contributed to field of neurorehabilitation >understanding axonal growth encourages new therapies to be tried > eg constraint-induced movements for stroke patients used and repeated practice using affected body while unaffected is restrained> helps med professionals know when interventions required.
split brain
-normal brain will immediately shared info between hemispheres giving complete picture of visual world
-but presenting image to one hemisphere of split brain = info cant be conveyed from one hemisphere to another
-object shown to RVS (LH) ppt can describe what they see
-object shown to LVF: cannot describe what they see, can select matching object behind screen using left hand, can select object closely associated with pic and pinup picture shown to LCF ppt giggled but reported seeing nothing
-demonstrated how certain functions are lateralised LH= verbal RH= silent but emotional
+research support > split brain ppt perform better than connected brain in certain tasks> eg faster at identifying odd one out in array of similar objects than normal controls > in normal brain LH superior processing abilities watered down by inferior RH > supports sperrys earlier findings that left and right brain have distinct roles
—– generalisation issues > split brain bhvr compared to neurotypical control group without epilepsy (cofouding variable) > differences observed may due to epilepsy rather than split brain > some unqiue features of split brain ppt cognitive abilities may have been due to their epilepsy
hemispheric lat
-localisation = same functions governed by specific areas of brain eg lang = brocas and wernickes
-lateralisation = brain has 2 hemisphered but some functions appear in both hemispheres eg vision
-lang is both lat and loc
-lang centers only in LH so lang is lateralised but RH can produce rudimentary words and contribute to emotional context
-lh = analyser rh = synthesiser
-some functions not lateralised eg motor somatosensory and vision on both sides of brain
-contralateral wiring = brain cross wired. motor area in RH controls movement in left side body vice versa
-vision = contralateral and ipsilateral each eyes recieves info fro LVF AND RVF. lvf in both eyes connected to rh vice versa and this aids with perception
+normal brains = 2 hemispheres process info differently > PET scan identify brai activity during visual procesing task > normal ppt asked to attened to global elements of image and regions of RH were much more active > focus on finer details = specific areas of LH tended to dominate > hemispheric latg is feature of normal brain and split brain
—— LH= analyser and RH= synthesiser is wrong > research = no dominant side of brain which creates different personality > analysed brain scans from 1000 ppl aged 7-29> found people used certain hemisphere for certain tasks (evidence for lat) but no dominant side so no artist or math brain > notion of l/r brained ppl is wrong
loc of function of brain
-theory that diff areas of brain are responsible for diff bhvr and processes
-hollistic as all parts of brain involved in processing of thoughts and actions
-diff parts perform diff functions and involved in diff body parts if area of brain becomes damaged through injury the function associated with area will also become affected
-cerebral cortex = outerlayer of hemispheres responsible for higher levels of processing eg problem solving. human cortex more deveoped than other mammals
-4 lobes
-frontal - motor area - voluntary movements in opposite body side. damage = loss of control over fine movements
-parietal lobe -somatosensory - sensory info from skin = sensitive
-occipital lobe - visual area - ea h eye send info from RVF to LVcortex vice versa damage = blidness in opposite visual field
-temporal - auditory - analyses speech - damage = hearing loss not compensate languag
-broca = left frontal lobe = speech production damage = brocas aphasia = slow speech and lack frquency
-wernicke = left temporal lobe =lang comprehension = wernickes aphasia = nonsense words fluent but meaningless
+brain scan evidence for localisation > peterson > werickes area active during listening ask and brocas active during reading task > tulving: scans show episodic snd semantic memories stored in diff parts of pre-frotal cortex - objective measure providing scientific evidence that many brain functions are localised
+ cs by phineas gage > railroad preparingh for blast accidently dropped tamping iron onto rock causing explosives to ignite > metre length rod went through skull from top of his brain talking off portion of it mainly left fromntal cortext > ledft mark o his personality > calm and reserved to quick tempered and rude
brain scans
fmri
- changes in blood 02 and flow due to neural activity more active = more o2 to meet demand
-produced 3d image showing parts involved in partiuclar mental processes
+ no radiation > risk free if administefred correctly > non invasive and straight foward to use
—– expensive > poor tewmporal resolution> 5 sec time lag behind image on screen and initial neuron firing > may not truely represent moment -to moment brain acxtiviity
eeg
-electrical activity withi brain vbia electrrode fixed to personal scalp using scalp cap
-clinitians use to diganose abnormalities eg epilepsy
+ study stages of sleep
+high temporal resolutio > easy to detect brain activity and resolution of sigle milisec
—– doesnt allow us to distinguish between activities originating in diff but adj loc
ERP
- statistical averaging technqiue
-all extraneous brain activit filtered out leaving related ones
-ERPS = brainwaves triggered by particular events
+excellent temporal resolution compared to fmri > measure cognitive functions and deficits > allocation of resources and working memory
—–lack standardisation > difficult to confirm findings
-extranous variables likke background noise must be eliminated
post morterm
-analysis of brain of dead person
-rare disorders mainly
-damages areas examined to find out cause of death
-comparison of neurotypial brain
+understand b rain processes eg broca = speech prod wernickes = lang comprehension
-ethical no consent
fioght or flight
-endocrine and ANS working together
-stressor percieved
-hypothalamus activates piturtary gland which releases ACTH
-ACTH affects adrenal gland to secret adrenaline into blood stream
-ans changes from resting state (parasympathetic ns) to sympathetc ns where physilogical changes occur eg increased heart rate
-once stressor passed > parasympathetic s returns body t normal resting state
circadian rhythm
-last aroudn 24 hours
-eg s/w cycle
-bio rhytms exert important influence on way body systems behave
-governed by 2 things : endo pm , exo ziegeber
s/w cycle
-governed by endogenous pm SCN lies abut optic chaism proving info from eyes about ligt to SCN > pinra gland > melatonin
light can reset SCN to our 24 hr day rather 25 known as entrainment
-Your core body temperature also changes over a 24hr period.
It’s at its lowest at about 4.30am (360c) and its highest at about 6pm (380c).
Sleep occurs when core temperatures start to drop, and start to rise again in the last few hours of sleep, this promotes alertness.
A small drop in temp’ also happens at 2-4pm (after lunch) which can explain why we feel sleepy in the afternoon.
Siffre’s cave study
-spent several extended periods underground to study the effects on his own biological rhythms.>Deprived of exposure to natural light and sound, but with access to adequate food and drink, resurfaced in mid-September after two months in the caves of the Southern Alps believing it to be mid-August! -A decade later he performed a similar feat but this time for six months in a Texan cave.
-In each case, his ‘free-running’ biological rhythm settled down to one that was just beyond the usual 24 hours (around 25 hours) though he did continue to fall asleep and wake up on a regular schedule.
Aschoff and Wever convinced a group of participants to spend four weeks in a World War 2 bunker deprived of natural light. All but one of the participants (whose sleep/wake cycle extended to 29 hours) displayed a circadian rhythm between 24 and 25 hours. Both Siffre’s experience and the bunker study 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
studied a group of 12 people who agreed to live in a dark cave for three weeks, retiring to bed when the clock said 11.45 pm and rising when it said 7.45 am. Over the course of the study, the researchers gradually speeded up the clock (unbeknown to the participants) so an apparent 24-hour day eventually lasted only 22 hours!
It was revealed that only one of the participants was able to comfortably adjust to the new regime. This would suggest the existence of a strong free-running circadian rhythm that cannot easily be overridden by exogenous zeitgebers.
+shift work
-understanding of the adverse consequences that occur when they are disrupted.
-E.g, night workers engaged in shift work experience a period of reduced concentration around 6 in the morning meaning mistakes and accidents are more likely .Research has also pointed to a relationship between shift work and poor health - shift workers are three times more likely to develop heart disease than people who work more typical work patterns (Knutsson 2003).
-This shows that research into the sleep/wake cycle may have real-world economic implications in terms of how best to manage worker productivity.
—–generalisations are difficult to make.
-The studies described on the facing page are based on very small samples of participants. It seems that sleep/wake cycles may vary widely from person to person.
a study by Duffy et al. (2001) revealed that some people have a natural preference for going to bed early and rising early (known as larks) whereas others prefer the opposite (owls). Even Siffre, in a later 1999 study, observed that his own sleep/wake cycle had slowed down since he was a young man.
-This means that it is difficult to use the research data to discuss anything more than averages, which may be meaningless.
infradian rhythms
-frequency of less than one cycle in 24 hours, such as menstruation and seasonal affective disorder.
-governed by monthly hormone levels which regulate ovulation
-typically takes 28 days
-rising levels of oestrogen cause the ovary to develop an egg and release it
-progesterone makes the womb lining grow thicker ready for an egg
Stern and McClintock studied 29 women with a history of irregular periods.
Samples of pheromones were gathered from nine of the women at different stages of their menstrual cycles, via a cotton pad placed in their armpit.
-The pads were worn for at least 8 hours to ensure that pheromones were picked up. The pads were treated with alcohol and frozen, to be rubbed on the upper lip of the other participants.
-On day one, pads from the start of the menstrual cycle were applied to all 20 women, on day two they were all given a pad from the second day of the cycle, and so on.
-Stern and McClintock found that 68% of women experienced changes to their cycle which brought them closer to the cycle of their ‘odour donor.
-depressive disorder which has a seasonal pattern of onset, and is described and diagnosed as a mental disorder in DSM-5. -As with other forms of depression, the main symptoms of SAD are persistent low mood alongside a general lack of activity and interest in life.
-SAD is a particular type of infradian rhythm called a circannual rhythm as it is subject to a yearly cycle. However, it can also be classed as a circadian rhythm as the experience of SAD may be due to the disruption of the sleep/wake cycle and this can be attributed to prolonged periods of daily darkness during winter.
-Psychologists have hypothesised that the hormone melatonin is implicated in the cause of SAD. 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 this secretion process continues for longer. This is thought to have a knock-on effect on the production of serotonin in the brain - a chemical that has been linked to the onset of depressive symptoms.
+++++One strength of menstrual synchrony research is that it may be explained by natural selection.
-Synchronisation of the menstrual cycle, of the kind observed in the Stern and McClintock study, 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.
—One limitation of synchronisation studies is their 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 (e.g. Trevathan et al. 1993) have failed to replicate the findings.
-This suggests that menstrual synchrony studies are flawed.
ultradian rhythms
-biological rhythm with a frequency of more than one cycle in 24 hours, such as the stages of sleep (the sleep cycle).
-five distinct stages of sleep that altogether span approximately 90 minutes - a cycle that continues throughout the course of the night. Each of these stages is characterised by a different level of brainwave activity which can be monitored using an EEG
++-One strength of research into ultradian rhythms is that it has improved understanding of age-related changes in sleep.
-Sleep scientists have observed that SWS reduces with age. Growth hormone is mostly produced during SWS therefore this is reduced in older people. According to Cauter et al. (2000), 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.
—-One limitation of ultradian rhythms research is there is significant variation between people.
-Tucker et al. (2007) 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.
++ conducted in lab > control extranous variables eg temp anhd nose > more valid results
endogenous pacemaker
-Internal body clocks that regulate many of our biological rhythms, such as the influence of the suprachiasmatic nucleus (SCN) on the sleep/wake cycle.
-The SCN is located in the hypothalamus in both hemispheres and is one of the main EP’s (endogenous pacemakers) in mammals.
It is influential in maintaining circadian rhythms (e.g. the sleep/wake cycle).
The SCN lies directly above the optic chiasm, which is where nerve fibres connected to the eye, crossover on their way to the left and right visual areas of cerebral cortex.
It receives info from light from this structure and this continues when our eyes are closed which lets the biological clock adjust to changing patterns of daylight when we are asleep.
DeCoursey (2000)
Destroyed the SCN connections in the brains of 30 chipmunks who were then returned to their natural habitat and observed for 80 days.
The sleep/wake cycle of the chipmunks disappeared and by the end of the study a significant proportion of them had been killed by predators (presumably because they were awake, active and vulnerable to attack when they should have been asleep).
In another study, Ralph et al. (1990) bred ‘mutant’ hamsters with a 20-hour sleep/wake cycle.
When SCN cells from the foetal tissue of mutant hamsters were transplanted into the brains of normal hamsters, the cycles of the second group defaulted to 20 hours.
-pineal gland and melatonin
—-One limitation of SCN research is that it 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. (2000) 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.
——Another limitation is that endogenous pacemakers cannot be studied in isolation.
Total isolation studies, are extremely rare.
-Remember also that 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 may make 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.
—- ethics > generalisations of scn between chipmunks and hamsters made to brain as mammalians brains have similar sturcture but ethics involved exposed to risk
exogenous zietgebers
External factors that affect or entrain our biological rhythms, such as the influence of light on the sleep/wake cycle.
light as ez
-It can reset the body’s main endogenous pacemaker, the SCN, and thus plays a role in the maintenance of the sleep/wake cycle. -Light also has an indirect influence on key processes in the body that control such functions as hormone secretion and blood circulation.
social cues as an exogenous zeitgeber
-new born babies’ initial sleep/wake cycle is pretty much random. At about 6 weeks of age, the circadian rhythms begin and, by about 16 weeks, babies’ rhythms have been entrained by the schedules imposed by parents, including adult-determined 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 long distances.
-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.
-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 need not necessarily rely on the eyes to exert its influence on the brain.
——One limitation is that 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 tell a different story from the usual narrative. 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.
—-Another limitation is evidence challenges the role of exogneous zeitgebers Miles et al. (1977) recount the study of 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.
emergence of psych as a science
-bheaviourists - wtason and skinner
-scientific psych should only study phenoma that may be observed objectively and measured therefore focused on bhvrs they can see and use carefully controlled observations
-cognitive = linked mind t computer eg msm and testged their predictions about memory and attention using experiments > legitimate and higly scientific
biological = avantages of technology to investigate physiological processes in fmri ad eeg to study brain activityt new methods eg genetic testine gave better understanding about bhvr
—- not all approaches use scneitific methods > human istic perfers to focus on individual experiences and humans are active ppt in reserarch can respond to d.c.. > so scientific approach to study human thought and experience may not always be possible
+ modern psych research is scinetific > psych has some claims as a science > describe and understand and control bheaviour > cog and bio rely on scientific methods eg lab studies to investiagte theories in unbaised way > scientific discipline
introspection
- study the structure of the human mind by breaking down behaviours into their basic elements (structuralism)
-introspection = A systematic experimental attempt to study the mind by breaking up conscious awareness into basic structures of thoughts, images and sensations
-first to open a laboratory designated to the scientific study of psychological enquiry under controlled conditions - focus was on trying to understand psychological processes of perception (structuralism)
- introspection still used today in areas such as therapy and studying emotional states
—– subjective
relies primarily on non-observable responses and although participants can report conscious experiences they can’t comment on unconscious factors.
produces data that was subjective (varied) so it became very difficult to establish general principles, so experimental results are not reliably produced.
++++ scinetific
-some of his methods were systematic and well-controlled
-recorded in controlled lab environment
-extraneous variables were not a factor
-standardised procedure
- can be considered a forerunner for later scientific approaches
experimental design
independent group -Participants take part in 1 condition. Required a separate group for each condition then results for each group, usually by comparing mean results
-Avoids order effects > reduces boredom and fatigue
-Reduces demands characteristics
-Needs lots of participants > costly
-Difference between groups (participant variables) > may affect result; however random allocations can overcome this
repeated measures
Participants do all conditions
Results compared at the end
-Avoids participants variables as everyone does all the conditions
-Fewer people needed > less costly
-Order effects more likely > requires counterbalancing
-Demand characteristics more likely as participants are more likely to guess the aim.
matched pairs
Participants are matched in each condition for any characteristics that may affect performance. E.g. age, gender, IQ.
Results are compared between members of each pair.
-Reduces participant variables
- Reduces order effects and demand characteristics
-Very time-consuming > costly
Impossible to match pairs exactly (even for twins) > may be unexpected confounding variables.
