Localisation of function in the brain

Localisation of function in the brain

• KEY TERMS:
• Localisation of function - the theory that different areas of the brain are responsible for different behaviours, processes or activities.
• Motor area - A region of the frontal lobe involved in regulating movement
• Somatosensory area - An area of the parietal lobe that processes sensory information like touch.
• Visual area - A part of the occipital lobe that receives and processes visual information
• Auditory area - Located in the temporal lobe and concerned with the analysis of speech-based information
• Broca's area - An area of the frontal lobe of the brain in the left hemisphere (in most people) responsible for speech production.
• Wernicke's area - an area of the temporal lobe (encircling the auditory cortex) in the left hemisphere (in most people) responsible for language comprehension

Slide 2

Localisation vs holistic theory

• 19th Century - Broca and Wernicke found that different parts of the have different functions
• Before this, scientists thought every part of the brain was involved in processing thought and action
• If certain areas of the brain are damaged, the function associated with that area is also affected
• 

Brain hemispheres and the cerebral cortex

• The brain's divided into the right and the left hemispheres
• Activity on the left-hand side of the body is controlled by the right hemisphere
• Activity on the right-hand side of the body is controlled by the left hemisphere
• The cerebral cortex is the outer layer of the hemispheres, it's about 3 mm thick and is much more developed than animals
• The cortex appears grey due to cell bodies location
• 

The motor and somatosensory centre

• Motor area:
• - Back of the frontal lobe
• - Controls voluntary movement in opposite side of body
• - Damage could lead to loss of control over fine movements
• Somatosensory area:
• - Front of both parietal lobes
• - Separated from the motor area by the central sulcus which is like a valley
• - Sensory information from the skin is represented
• - The higher the sensitivity of an area on our body, the larger the amount of somatosensory area it takes up

The visual and auditory centres

• Visual area:
• - Occipital lobe at the back of our brain
• - Each eye sends information from the right visual field to the left visual
• - And from the left visual field to the right visual cortex
• - Damage to the left hemisphere, can produce blindness in part of the right visual field of both eyes
• Auditory area:
• - Temporal lobes house the auditory area
• - Analyses speech-based information
• - Depending on the amount of damage, would result in hearing loss
• - Damage to Wernickes area mat affect ability to comprehend language

The language area of the brain

• Language is restricted to the left side of the brain
• Broca (1880's) identified a small area of the left frontal lobe responsible for speech production
• Damage to Broca's area causes Broca's aphasia - slow laborious, speech, lacking in fluency
• 

Cont. the language area of the brain

• Wernicke desribed patients who had no problem producting language but struggled understanding it
• Speech they produced was fluent but meaningless
• Wernicke found an area in the left temporal lobe as responsible for language comprehension
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