ALL A01 and A03 Flashcards
HEMESPHERIC LATERLISATION / Split-brain research A01
The two hemispheres of the brain are connected by a bundle of nerve fibers called the corpus callosum.
In rare cases of extreme epilepsy, a surgeon may cut the corpus callosum (corpus callosotomy), separating the right and left hemispheres from each other. This contains any epileptic seizures to just one side of the brain, reducing their severity.
HEMESPHERIC LATERLISATION /
Split-brain research A01 : SPERRY 1968
When split-brain patients were shown an image to their right visual field, they were able to describe in words what they saw. However, when they were shown the same image to their left visual field, they were not able to describe what they saw. This is likely because visual information from the left side is processed in the right hemisphere (the visual cortex is contralateral) and language processing primarily occurs in the left hemisphere. So, the visual data in the right hemisphere could not be shared to the language processing areas in the left hemisphere in order for the split-brain patient to describe what they saw.
HEMESPHERIC LATERLISATION / Split-brain research A01 : SPERRY 1968 (2)
However, despite not being able to describe in words the image shown to the left visual field, the split-brain patients could use their hands to pick an object associated with that image. For example, if the split brain patient was shown a cigarette to their left visual field, they could use their left hand to pick an ashtray. This can be explained by the fact that the left hand is controlled by the right hemisphere (again, the motor cortex is contralateral) and the image that was shown to the left visual field would have been processed in the same (right) hemisphere.
Hemispheric Lateralisation (forest)
P: split brain has provided considerable research into lateralisation of brain function
E: fink et al -> pet scans used to identify which brain areas were active during a visual process task -> asked to attend to global elements of an image (e.g. a forest) RH was active,, focusing on finer details (e.g. one tree) activated the LH
E: shows left is centred on verbal and analytical tasks and right more on spatial and creative tasks
L: provides theory w/ validity
Hemispheric Lateralisation (sample)
P: problems w/ sample
E: the sample was small and had limited amount of split brain patients available but it unethical to manipulate IV so there was little that could be done to change this
E: regardless, it reduces population validity bc it’s a unique group so there’s considerable difficulty generalising to the wider population
L: weakness in methodology reduces external validity of the study and questions the necessity of the material if it can’t be applied well on a wider scale
Hemispheric Lateralisation (age)
P: Lateralisation may only be applicable for certain age groups
E: Szaflarski et al found that language became more lateralised to the left hemisphere in children and adolescents but lateralisation decreased after 25 as lateralised functions switched to bilateral functions in adulthood
E: suggests lateralisation changes with normal ageing. This may likely be because using the extra processing resources of the other hemisphere may compensate for age-related declines in function
L: research into lateralisation is not as effective for the wider population as it cannot be generalised to all age groups
LOCALISATION OF BRAIN FUNCTION A01
Localisation of function refers to identifying specific areas of the brain that correspond to specific functions. For example, damage to the auditory cortex in the brain can damage hearing, whereas damage to the motor cortex may reduce a person’s ability to move. This suggests these functions are localised within these areas of the brain.
Localisation (case study)
A
P: supporting evidence
E: phineas gage -> damaged left frontal lobe in railroad accident and had a personality change from calm to quick tempered
E: case study of neurological damage shows frontal lobe is responsible for regulation mood, showing mood is localised to that area’
L: supports localisation
CA: problems w/ case studies -> difficult to make meaningful generalisations from the findings of a single individual. Conclusions drawn may depend on subjective interpretation of researcher.
Localisation (brain scans)
A
P: supportive evidence
E: peterson used brain scans to demonstrate how wernicke’s area was active during a listening task and brocas was active during a reading task
E: shows many everyday brain functions are localised -> lang centres found in wernickes and brocas and localised to LH (distinguishable and separate)
Extra: supported by methodology -> nomothetic method provides empirical evidence that gives a scientific cred to research, increases validity and reliability
Localisation (counter argument)
A
P: Language production may not be confined to Broca’s area alone
E: Dick and Tremblay -> only 2% of modern researchers think that language in the brain is completely controlled by Broca’s area and Wernicke’s areas. This is supported through modern FMRI scans that show language function is distributed more holistically and lang streams have been identified across the cortex
E: this is a limitation bc it suggests that the localisation may be an outdated theory and provide a limited explanation for brain function. With modern research providing a more scientific basis with empirical evidence, it provides a strong foundation to counter localisation
L: localisation theory may provide only a partial explanation, and so more modern theories such as brain plasticity and functional recovery could prove to be more well rounded explanations
FUNCTIONAL RECOVERY AFTER TRAUMA A01
