The brain is lateralized i.e. twosides (hemispheres)
Localized:
Some functions are localized and appear in both left and righthemispheres (LH and RH)
E.g. auditory, visual, motor, somatosensory areas
Localized and lateralized:
Two main language centres are in the LH (for most people) - Broca's area (leftfrontallobe), Wernicke's area (lefttemporallobe)
Righthemisphere produces rudimentary words but provides emotional context. Lefthemisphere may be the analyzer, righthemisphere the synthesizer
Contralateral:
In the motor area, the righthemispherecontrols the leftside of the body and viceversa (cross-wired)
Contralateral and ispilateral:
Leftvisualfield (LVF) of both eyes is connected to the righthemisphere and rightvisualfield (RVF) of both eyes is connected to the lefthemisphere
Enables the visualareas to compare the slightlydifferentperspective from each eye and aidsdepthperception
Same arrangement for auditory areas
One strength is evidence of lateralized brain functions in 'normal' brains
PET scans show when 'normal' ppts attend to globalelements of an image, the righthemisphere is more active
When required to focus on finerdetail the specificareas of the lefthemisphere tend to dominate (Fink et al 1996)
This suggests that hemisphericlateralization is a feature of the normal brain as well as the split-brain
One limitation is the idea of analyzer versus synthesizer brain may be wrong
There may be differentfunctions in the righthemisphere and lefthemisphere but research suggests people do not have a dominantside, creating a differentpersonality
Nielsen et al (2013) analyzed 1000brainscans, findingpeople did use certain hemispheres for certain tasks but nodominance
This suggests that the notion of right- or left-brained people is wrong (e.g. 'artist'brain)
Evaluation extra: Lateralization versus plasticity
Lateralization is adaptive enabling twosimultaneoustasks with greaterefficiency, e.g. only lateralizedchickens better at findingfood while watching for predators (Rogers at al 2004)
On the other hand, neuralplasticity is also adaptive. After damage to brain, languagefunction can 'switchsides' (Holland et al 1996)
This seems to suggest that lateralization is firstpreference but ultimately plasticity is more important because it deals with loss of lateralization