Localisation of function in the brain and hemispheric lateralisation Flashcards
Localisation of function in the brain
The theory that certain functions have certain locations within the brain.
Motor area
Location- frontal lobe.
Function- responsible for voluntary movements by sending signals to muscles in the body.
Hemisphere- both. motor area on one side of the brain controls muscles on opposite side.
Somatosensory area
Location- parietal lobe
Function- receives incoming sensory information from the skin and produces sensations related to pain, pressure etc..
Hemisphere- both. somatosensory area on one side of the brain receives sensory information from the opposite side of the body
Visual area
Location- occipital lobe
Function- receives and processes visual information
Contains different parts that process different types of information such as color, shape or movement.
Hemisphere- both. information from the right-hand side of the visual field is processed by the left hemisphere and vice versa.
Auditory area
Location- temporal lobe
Function- responsible for analysing and processing acoustic information.
Hemisphere- information from the left ear is processed by the right hemisphere and vice versa
Broca’s area
Named after Paul Broca
Performed brain autopsy on Patient Tan (who could only say ‘tan’) after he died.
Broca found that Tan had a lesion in the left frontal lobe (Broca’s area) and concluded that this area must be responsible for speech production and this damage prevented Tan from speaking fluently.
Wernicke’s are
Named after Carl Wernicke
Discovered a group of patients who could talk but not understand language
He found that the left temporal lobe (wernicke’s area) in their brains had damage to it.
He concluded that this area must be responsible for understanding and comprehending language.
Evaluation of localisation
Equipotential theory argues that although basic brain functions such as sensory and motor cortex functions are controlled by localised areas, higher cognitive functions are not localised.
Fails to take into account individual differences - women were found to have a larger broca’s area and wernicke’s area compared to men, possibly due to their greater use of language.
Hemispheric lateralisation
The idea that some functions are found only in one hemisphere of the brain. eg. the left is dominant for language and right for visuo-motor tasks.
Sperry split-brain research
Sperry et al. (1967) were the first to investigate hemispheric lateralisation with the use of split-brain patients.
Aim- to examine the extent to which the two hemispheres are specialised for certain functions.
Procedure- participants sat in front of a board of horizontal rows of lights and were required to stare at the middle point. The lights then flashed across their left and right visual fields.
They reported lights had only flashed on the right side of the board.
Findings- when their right eye was covered and the lights were flashed on the left side of their visual field they claimed not to have seen any lights at all. However, they could point at the light that lit up.
Conclusion- this shows that they had seen the lights in both hemispheres but the material shown to the left eye could not be spoken about as the right hemisphere has no language centre and cannot speak about the visual information it has received.
Evaluation of split-brain research
Split-brain patients often had other neurological problem which might have acted as cofounding variables.
Sperry’s original claim that the right hemisphere couldn’t process even basic language was contradicted by recent a recent study on JW. Following a split-brain procedure obtained the ability to speak out of his right hemisphere which means that he could speak about information presented his lvf.
Brain Plasticity
The brain’s ability to change and adapt as a result of experience. It does this by reorganizing it’s structure, functions and connections
Functional recovery
The transfer of functions from a damaged area of the brain to other undamaged areas of the brain.
Done through neuron unmasking when ‘dormant synapses’ open connections to compensate for nearby damaged areas of the brain.
