biopsychology year 13 Flashcards
what is localisation of function
specific locations within the brain have specific functions
what is the motor cortex responsible for
voluntary movements
where is the motor cortex located
in the frontal lobe along the precentral gyrus
what does contralateral mean
that the brain is cross wired and the hemispheres control opposite sides of the body
what is the boundary between the frontal and parietal lobe called
central sulcus
what is the somatosensory cortex responsible for
processing sensory information related to touch to specific body regions
where is the somatosensory cortex located
parietal lobe along the postcentral gyrus
where is the visual cortex located
occipital lobe
what is the visual cortex responsible for
processes different types of visual information
how does visual information go to the visual cortex
- Begins in the retina where light enters 2. Strokes the receptors
- The nerve impulses are then transferred to the brain via the optic nerve
- Then the thalamus acts as a relay station passing the information to the visual cortex
where are the auditory centres located
in the temporal lobes
what are the auditory centres responsible for
processing sound information from the cochlea
where is brocas area located
posterior frontal lobe of the left hemispheres
what is the Brocas area responsible for
it is responsible for speech production
where is Wernickes area located
posterior temporal lobe in the left hemisphere
what is Wernickes area responsible for
understanding language
limitations for localisation of the brain
- some believe higher mental functions aren’t in one single area and that when a person suffers minor brain damage the intact areas of the cortex can take over responsibility for the function that is no longer able to be done and this has shown in patients with brain damage learning how to walk again even if there is damage to the area of original function
- communications between the areas of the brain may be more important than the localisation of functions and Joseph Dejerine described the case of a patient losing the ability to read due to damage to the connection between the visual cortex and Wernickes area showing complex behaviour uses multiple different structures
- individual differences in language areas as Harasty et al found that women have proportionally larger Brocas and Wernickes area than men and this resulted in women having a greater use of language
strength of localisation of function
+ Aphasia studies as there are two types of aphasia that effect a person and Broca’s aphasia is an impaired ability to produce language and this is caused by brain damage in Broca’s area. Wernicke’s aphasia causes people to have an impaired ability to extract meaning from spoken or written words and this was because of damage to Wernicke’s area.
+ Phinneas gage case study evidence of localisation and his personality change
what is hemispheric lateralisation
the two hemispheres of the brain are not alike and each hemisphere has functional specialisations
what are the specialisations of the right hemispheres
visual motor skills
what are the specialisations of the left hemispheres
dominant in speech and language
what are the hemispheres connected by
a bunch of nerve fibres called the corpus collosum allowing communication between them
what are the limitations of lateralisation
- lateralisation changes throughout a persons life and changes with aging. Szaflarski et al found that language became more lateralised to the left hemisphere with age up to 25 but then it decreases at an older age due to hemispheric compensation
- J.W developed the capacity to speak out of the right hemisphere with the result that he can now speak about information presented to the left hemisphere or to the right
what are the strengths of hemispheric lateralisation
+ lateralisation provides an advantage. Rogers et al found that in chicken lateralisation is associated with the ability to perform two tasks simultaneously and this finding shows lateralisation enhances the brain efficiency in cognitive tasks that demand use of both hemispheres
+ supporting research with Sperry and Gazzaniga study on epileptic patients with their corpus collosum cut
what is brain plasticity
the brains ability to change and adapt as a result of experience
what 4 pieces of supporting research are there for brain plasticity
- Boyke et al- 60 yo ppts practised juggling everyday found increases in grey matter in the visual cortex and when they stopped practising the grey matter went back
- Kuhn et al- college students who played Mario Kart for 30 minutes a day for 2 months and those who did not found grey matter shift correlated to areas needed to perform the game
- Kempermann et al- two different groups of rats in a enriched environment or boring and they found that the rats in the enriched area had increased neurons in the hippocampus
- Maguire et al- studied London cab drivers to discover whether changes in the brain could be detected because of their extensive navigational experts. Compared London taxi drivers to average person and found that the cab drivers have more posterior hippocampi.
what are the 2 mechanisms of recovery and explain what each of them do
- Neuronal unmasking – dormant synapses which under normal conditions these synapses are ineffective but an increasing rate of input to the synapses due to electrical impulses going through new areas around the damaged area
- Stem cells- stem cells can be infused into the damaged site in the brain and there are 3 different hypotheses of how this works: replacing dead cells, rescue injured cells and form a brand-new neural network
supporting research for functional recovery working after trauma
- Tajiri got lab rats and gave them a server brain injury and randomly assigned them to 2 groups one getting stem cells into the injured site and one which just had a solution injected. They found if you had the stem cells the damage was getting better, and they had a solid stream whereas the rats with the solution had no solid stream of neurons.
- Schnider et al found that patients with the equivalent of a college education are 7x more likely than those who didn’t finish high school to be disability free one year after a moderate to severe traumatic brain injury. 796 patients studied 214 had achieved disability free recovery after one year. 39% of the patients had 16 or more years of education, 30% had 12-15 years of education and just 10% had less than 12 years of education.
what are the ways of studying the brain
Post mortem
fMRI
EEG
ERP
describe studying the brain with an fMRI
Measures changes in the brain activity while a person performs a task and it does this by measuring blood flow in particular areas of the brain which indicated increased neural activity in those areas. The increase in activity leads to a higher need for oxygen and therefore more blood.
strengths of studying the Brain with fMRI
+ good spatial resolution of 1mm and precisiely identifies active brain regions and patterns of acitvation
+ produces a moving picture which allows comparison overtime
+ non evasive
limitations of studying the Brain with fMRI
- machines are very expensive and are very hard to build leading to small sample sizes
- the ppt had to remain still for a long period of time leading to inaccuracies and time consumption
- bad temporal resolution as the scan takes longer to produce than the underlying neural processes, and temporal information is thereby heavily blurred.
describe studying the brain with an EEG
Measures electrical activity in the brain. Electrodes placed on the scalp detect small electrical changes resulting from the activity of the brain cells and the electrical signals are graphed over a period of time resulting in the representation called the EEG. The EEG data can be used to detect various types of brain disorders. The four basic patterns are alpha waves, beta waves, delta waves and theta waves. Awake and relaxed = alpha, Physiologically aroused= beta waves, Asleep= delta
strengths of studying the brain with an EEG
+ cheaper alternative way to scan a brain and therefore bigger sample size
+ historically important in understanding the brain and studying it
limitations of studying the brain with an EEG
- only reasonably accurate and the finer details are often missed
- expertise are needed to read the data and interpret it
- not able to detect deep activity in the brain and only records surface level electrical brain activity
describe studying the brain with an ERP
ERPs are very small voltage changes in the brain that is triggered by stimuli. ERP’s are difficult to pick out from all the other electrical activity being generated within the brain at a given time. To establish a specific response to a target stimulus requires many presentations of the stimulus and these responses are then averaged. ERPs can be divided into two categories 1 being the waves occurring within the first 100 milliseconds, 2 being after the first 100 milliseconds.
strengths of studying the brain with an ERP
+ cheaper alternative to brain scanning so can have a bigger sample
allows researchers to isolate and study how an individuals cognitive processes take place
+ good temporal resolution
+ Can be used to find out if a young child is deaf as they wont have voltage changes when presented with sound,
limitations of studying the brain with ERP
- some cognitive processes can not be studied using ERPs as they are unable to be presented multiple times
- brain activity deep in the brain is not detected and misses finer details
describe studying the brain with a post-mortem
Used to establish the underlying neurobiology of a particular behaviour and
researchers can examine their brains to look for abnormalities that might explain that behaviour and which are not found in control individuals. Example of this is TAN who displayed speech problems when alive and subsequently was found to have a lesion in the brain now known as Broca’s area
HM’s postmortem confirmed that HM’s inability to store new memories was linked to lesions the hippocampus
Post-mortems have also found evidence of reduced numbers of glial cells in the frontal cortex of patients with depression – Cotter et al 2001
limitations of studying the brain with post-mortems
- brain activity cannot be measured
- brains can change after death and therefore you don’t have the true state of the persons brain before they died
- difficult to compare a brain after death with the functioning prior to death and you can find a correlation but not a cause
strengths of studying the brain with post-mortems
+ the individual is dead and there is not issue of consent or discomfort
+ it was the first step in studying the brain and developed out fundamental knowledge of the structures of the brain e.g. Phineas gage
what is a circadian rhythm
a cycle 24 hours long that is responsible for matching you to your environment
what is the master circadian pacemaker and what does it do
The SCN (superchiasmatic nucleus) which tells is found in the hypothalamus and tells the pineal gland to produce melatonin which is a hormone that makes you sleepy which is why you struggle to wake up in the winter
what is photoentrainment
Light provides the primary input to this system setting the body clock to the correct time
how does the sleep wake cycle
Keeps us awake in daylight and makes us sleep in night
It is describes as free running which means that even if we are in the absence of light we would still sleep at a normal time
what happens in the core temperature cycle
Sleep begins when the core temperature begins to drop and stops when it begins to rise
what happens in the hormone production cycle
the production of melatonin from the pineal gland follows a rhythm with peak levels in the hours of darkness.
outline Michel Siffre research into circadian rhythms
(6)
Michel Siffre subjected himself to long periods of living underground in order to study his own circadian rhythm and he had no external cues to guides his rhythms.
- After his first stay underground of 61 days he resurfaces on the 17th of September thinking it was the 20th of august
- the second he spent 6 months in a cave in Texas and let his circadian rhythm take over and he had a 24 hour one with some dramatic variations however
- his final underground stay he was interested in the affects of aging on the circadian rhythm and he found his body ticked more slowly then when he was younger and his circadian rhythm stretched to 48 hours at times
outline the 2 studies that support Michel Siffre findings about free running circadian rhythms
Aschoff and Wever:
- placed ppts in underground WW2 bunker in absence of external cues
- found circadian rhythms stayed between 24-25 hours but there were some individual differences of 29 hours
Folkard
- a group of 12 in a cave for 3 weeks isolated from external cues. volunteers agreed to go to sleep at 11:45 on the clock and get up when it was 7:45 and gradually the researchers changed the clock so it was 22 hours and not 24
- their rhythm stopped matching the clock when they quickened it and kept to the 24 hours
evaluate the importance of external factors on circadian rhythms
+ supporting research: highest tested the hormone release in 4 ppts stationed at the British Antarctic Station and their cortisol levels were at the highest points when they woke up and at the lowest points when they went to sleep. But when it was dark for 3 months their peak cortisol level was in the noon rather then the morning showing daylight is responsible for variations in circadian hormone release.
- individual differences: cycle length can vary from 13-65 hours and Duffy found that morning people tend to rise early and go to bed early whereas evening people wake later and go to bed later.
+ practical applications: chronotherapeutic the study of how timing affects drug treatments and we know that people with heart problems are most likely to suffer a heart attack early in the morning so we can design chronotherapeutic medications which administer the drugs to prevent heart attacks in the morning when they are taken the night before
- temperature may be more important than light is. Buhr et al believes that body temperature fluctuates on a 24 hour cycle and even small changes in temp can send powerful signals to the cells in out body and therefore cause tissues and organs to become active or inactive.
what is an ultradian rhythm and 2 examples
a cycle less than 24 hours like the sleep wake cycle, BRAC cycle
describe the sleep stages
they repeat every 90 minutes and there are 4 stages
stage 1- not true sleep and is around 5-7 minutes
stage 2- true sleep and is around 10-25 minutes
stage 3- deep sleep and is around 20-40 minutes
stage 4- REM sleep and is around 10-60 minutes
describe the BRAC cycle
90 minute cycle when we are awake and is the cycle of the brain moving progressively from a state of awareness to a state of physiological fatigue and research suggest that a human mind can focus for a period of 90 minutes and then runs out of resources resulting in loss of concentration
what is an infradian rhythm and give 2 examples
rhythms that have a duration longer than 24 hours like the menstrual cycle and annual rhythms
what are endogenous pacemakers
Anything innate and a product of inherited genetic mechanisms that allow us to keep in pace with environment
what route does light take to melatonin
Light levels —> retina —-> optic nerve —> SCN —> Pineal gland —> produces melatonin
what are exogenous zeitgebers
environmental events that are responsible for entraining the biological clock of an organism.
how does light work as an exogenous zeitgeber
Light- receptors in the SCN are sensitive to light changes during the day and use this to synchronise activity of the body’s organs and glands. A protein called melanopsin which is sensitive to natural light is critical as the protein is in cells carry signals to the SCN to set the daily body cycle.
give 2 example of exogenous zeitgebers
light and social cues
evidence for endogenous pacemakers
Morgan- bred a strain of hamsters so that they had abnormal circadian rhythms of 20 hour instead of 24 and transplanted the SCN neurons into brains of normal hamsters and the normal hamsters then displayed the abnormal 20 hour circadian rhythm. It was also do vice versa and that also worked.
Folkard studied university student who spent 25 days in controlled lab environment with no daylight or zeitgebers and at the end of the 25 days he core temp rhythm was still 24 hours. However her sleep wake cycle extended to 30 hours.
evidence of exogenous zeitgebers
Skene and Arendt estimate that the vast majority of blind people who still have some light perception have normally entrained circadian rhythms suggesting the pathway from retinal cells to the SCN is still intact and the blind people with no light perception show abnormal circadian entrainment
Burgess found that exposure to bright light prior to an east west flight decreased the time needed to adjust to jet lag
Vetter et al investigated importance of light regulation of the sleep wake cycle of 5 ppts over a 5 week study. one group had warm artificial light and the other blue enriched light. ppts under warmer light synchronised their rhythm and the ppts with blue enriched light did not.
what did Tucker et al do
ppts studied in lab in 11 consecutive days and nights in a strictly controlled lab. the researchers assesed sleep durationi, time to fall asleep and the amount of time in each sleep stage. They found large individual differences even though they all had the same conditions and therefore biology must also have an effect on sleep wake cycles.
what is the supporting research for BRAC
Ericsson et al studied a group of elite violinists and found that among the group those that practice sessions were limited to no more than 90 minutes were better. Also found that the better violinists napped to recover from practice.
evidence for infradian rhythms
Russel- daily samples of sweat were collected from one group of women and rubbed on the lips of another group of women and their menstrual cycle synced.
Penton Voak et al- human mate choice varies in the cycle. When ovulating women showed a preference for masculine men but when picking a long term partner went for feminine men.