Biopsychology Flashcards
localisation of function
Specific functions have specific locations within the brain
Role of the motor cortex
generating voluntary movements
Location of the motor cortex
frontal cortex in both hemispheres
How the motor cortex works
Different parts of the motor cortex control different parts of the body which are arranged logically
the motor cortex on one side of the brain control the opposite side of the body
role of the somatosensory area
detects sensory events coming from different regions of the body
somatosensory area location
parietal lobe
How the somatosensory cortex works
Using sensory information for the skin the somatosensory area produces sensations of touch pressure pain and temperature which it then localises to specific body regions
the cortex on one side of the brain receives information from the opposite side of the body
Where is the primary visual centre
Visual cortex in the the occipital lobe
How does visual processing work
Light hits the retina at the back of the eye photoreceptors in the retina send nerve impulses to the brain via the optic nerve terminating in the thalamus which acts as a relay station before passing information to the visual cortex
How does the visual cortex work
Each side of the visual cortex receives information from the opposite side of the visual field
The cortex contains different areas for processing different types of information e.g. colour shape and movement
Where is the primary auditory centre
The auditory cortex within the temporal lobes on both hemispheres
How does auditory processing work
Sound waves are converted into nerve impulses in the cochlea of the ear. These impulses travel via the auditory nerve to the brain stem for basic decoding (e.g. intensity and duration) then the thalamus as a relay station and for further processing before proceeding to the auditory cortex in the brain.
How the auditory cortex works
The sound has largely been decoded by this point but in the cortex it is recognised and may result in an appropriate response
What are the 2 primary language centres
Broca’s and Wernicke’s areas
Where is Broca’s area
Posterior portion of the left frontal lobe
Function of Broca’s area
Speech production
How Broca’s area was discovered
Treated patient who could only say “tan” but could understand spoken language
Brain was studied and he had a lesion in his left frontal lobe
8 other patients with a similar language deficits were studied and had the same damage.
Patients with legions in the same area on the right did not have the same problems
Where is Wernicke’s area
Posterior left temporal lobe
Function of Wernicke’s area
Understanding language
Localisation of function evaluation - evidence from neurosurgery
Neurosurgery is a last resort for treating some mental disorders, targeting specific areas of the brain which may be involved e.g. cingulotomy’s for OCD where the cingulate gyrus is isolated
Dougherty reported on 44 cingulotomy patients and 32 weeks post surgery 30% had a successful response.
suggests behaviours associated with mental disorders may be localise
Localisation of function evaluation - communication over localisation
It may be more important how areas of the brain communicate rather than which specific regions control specific processes
Although different regions may have specialist functions to work they must interact with each other e.g. loss of ability to read resulted from damage to connections between visual cortex and Wernicke’s area.
Suggests complex behaviour are built up as stimulus enters the brain and moves through different structures before a response, damage to connections may resemble damage to localised region
Localisation of function evaluation - brain scans
Petersen et al (1988) used brain scans to demonstrate how Wernicke’s area was active during a listening task
Localisation of function - distributed function of learning
Lashley (1950) removed areas of the cortex between 10%-50% in rats that were learning the route through a maze. No area was proven to be more important than any other in terms of the rats ability to learn the route. Learning seemed to require every part of the cortex
What is hemispheric lateralisation
Some mental processes in the brain are mainly specialised to either the left or right hemisphere
How are the 2 hemispheres of the brain connected
A bundle of nerve fibres called the corpus callosum
Who are split brain patients
People who have had their corpus callosum cut
Often performed to treat very severe epilepsy
As the corpus callosum is cut the two hemispheres cannot interact and information has to be processed within the hemisphere it was received in
Sperry and Gazzaniga - procedure
Studied split brain patients to test the abilities of each hemisphere one at a time
patient fixate on a dot in the centre of a screen
Information was presented to the left or right visual field then asked to make responses with the left or right hand without being able to see what their hands were doing
Sperry and Gazzaniga - findings
left hemisphere is responsible for speech and language
Right hemisphere responsible for visual-spatial processing
Example - picture of dogs flashed on the right visual field patient would know they saw a dog as the left hemisphere processes information from the left and is responsible for speech if flashed to the left visual field the patient would say they see nothing as the right hemisphere processes the left visual field but does not have a language centre so cannot say what it saw
What does the left hemisphere do
language
controls the right side of the body
What does the right hemisphere do
Emotions
Visual-spatial processing
controls the left side of the body
lateralisation evaluation - lateralisation in connected brains
Fink et al (1996) used PET scans to identify which brain area were active during a visual processing task
When participants with connected brain were asked to attend to global elements of an image e.g. a whole forest the right hemisphere was more active but when focusing on finer detail e.g. individual trees the left hemisphere was more active
Lateralisation evaluation - adaptive
adaptive as it enable two tasks to be performed simultaneously with greater efficiency
Rogers et al (2004) found that lateralised chickens could find food while watching for predators but normal chickens couldn’t
Split brain evaluation - generalisation
causal relationship is hard to establish as all the patients had epilepsy this is a major confounding variable as the results could be due to epilepsy not split brain
What is synaptic pruning
as we age rarely used connection in the brain are deleted and frequently used connections are strengthened. this pruning enables lifelong plasticity where neural connections are formed in response to new demands on the brain
What is brain plasticity
The brains ability to modify its own structure and function as a result of life experiences
Maguire et al (2000)
studied the brains of London taxi drivers
Found significantly greater volume of grey matter in the posterior hippocampus (area associated with spatial and navigational skill) than in the matched control group
What is functional recovery
The recovery of abilities and mental processes that have been compromised as a result of brain injury or disease
Mechanisms of functional recovery
Neuronal unmasking
Axonal sprouting
Recruitment of homologous areas
What is neuronal unmasking
“dormant synapses” which exist anatomically but have blocked function as the rate of neural input is too low. When a surrounding area becomes damaged input may increase and “unmask” the dormant synapse
What is axonal sprouting
The growth of new nerve endings which connect with other undamaged nerve cell to form new neuronal pathways
What is recruitment homologous areas
Recruitment of similar areas on the opposite side of the brain allowing specific tasks to continue to be performed
Plasticity evaluation - negative plasticity
plasticity can have negative behavioural consequences e.g. adaptations to drugs can lead to poorer cognitive functioning in later life as well as an increased risk of dementia or things like phantom limb syndrome
plasticity is not always beneficial
Plasticity evaluation - seasonal changes
seasonal plasticity in response to environmental changes e.g. there is evidence the suprachiasmatic nucleus shrinks in animals during spring and and expands throughout autumn
Functional recovery evaluation - real-world application
understanding the processes in functional recovery has contributed to the field of neurorehabilitation e.g. knowledge of axonal sprouting lead to constraint-induced movement therapy (constraining unaffected limb and repeatedly using the affected one)
Functional recovery evaluation - education level
Education level may influence recovery rates. Schneider found that the more time people with a brain injury had spent in education the greater their chances of a disability free recovery
What is fMRI
functional magnetic resonance imaging
detects changes in blood oxygenation and flow as a result of activity in specific parts of the brain
fMRI strengths
risk free as does not use radiation
non-invasive
high spatial resolution
fMRI limitations
expensive
poor temporal resolution (5-second time-lag)
What is EEG
electroencephalogram
measures electrical activity within the brain recording brainwave patterns
EEG strengths
High temporal resolution
non-invasive
EEG limitations
cannot pinpoint exact location of activity
cannot detect activity in deeper regions of the brain
What is ERP
Event-related potentials
Uses EEG
small voltage changes in the brain triggered by specific events or stimuli
stimulus presented many times then response is averaged
ERP strengths
good temporal resolution
can determine response to specific stimuli
ERP limitations
requires a large number of trials to gain meaningful data
cannot record electrical activity deep in the brain
What are post-mortem examinations
examining the brain after death
Post mortem strengths
allow for detailed examination of both anatomical and neurochemical aspects of the brain
can examine deeper regions of the brain
Post-mortem limitations
How the person dies may influence the post-mortem brain
causation cannot be established
ethical issues
What is a circadian rhythm
a pattern of behaviour that occurs approximately every 24 hours
Examples of circadian rhythms
sleep-wake cycle
core body temperature
hormone production
What is an endogenous pacemaker
internal biological clock which helps to govern a biological rhythm
Sleep wake cycle endogenous pacemaker and how it works
suprachiasmatic nucleus
lies above the optic chiasm receives information about light enabling the biological clock to adjust to changing patterns of daylight
the SCN sends information to the pineal gland so when it is night melatonin production increases to induce sleep
What are exogenous zeitgebers
external environmental factors that impact biological rhythms
Exogenous zeitgeber for the sleep wake cycle
light
Siffre procedure and findings
spent extended periods of time underground without exposure to light
his free-running biological rhythms settles to around 25 hours
Folkard procedure and findings
12 people living in a dark cave for 3 weeks with a clock
sleep at 11:45 and wake at 7:45
they gradually sped up the clock to make the day last 22 hours
only 1 person was able to comfortably adjust to the new regime
Circadian rhythms evaluation - shift work
understanding of adverse consequences when the cycle is disrupted e.g. night workers loosing concentration
real-world implication of how to manage productivity
Circadian rhythms evaluation - medical treatment
circadian rhythms co-ordinate with body processes e.g. heart attacks are most likely to occur in the morning so aspirin is taken in the night
circadian rhythms evaluation - individual differences
cycles ay vary widely from person to person e.g. Siffre = 25 hours
1 person in Folkard 22 hours
night owls and morning larks
difficult to use the research to discuss anything more than averages
What is an infradian rhythm
biological rhythm that lasts longer than 24 hours
What is an ultradian rhythm
Biological rhythm that lasts less than a day
