Localisation of function in the brain

• Localisation of function - he principle that specific functions have specific locations within the brain

  Flourens demonstrated that the main divisions of the brain were responsible for largely different functions
• Motor Cortex

  • Location - back of frontal lobe: the precentral gyrus
  • Responsibility - Generation of voluntary motor movements
  • Function - The motor cortex on one side of the brain control the muscles on the opposite side of the body. Damage may cause loss in control over fine movements
• Broca's area

  • Location - Frontal lobe of left hemisphere
  • Responsibility - Speech production
  • If Damaged - Leads to Broca's aphasia where people have speech that is slow, laborious and lacking in fluency
• Auditory centres

  Location - Temporal lobes on both sides of the brain

  Responsibility - Hearing

  Function - Sound is recognised and response produced

  Auditory processing - Sound waves are converted into nerve impulses in the cochlea which travel to the auditory cortex via the auditory nerve. The first stop is the brain stem which decodes the info, then the thalamus which acts as a relay station. The last stop is the auditory cortex.
• Somatosensory area

  • Location - Parietal lobe of the brain - postcentral gyrus. Separated from the motor area by the central sulcus
  • Role/Responsibility - Detects sensory events arising from different regions of the body
  • Function - Produces sensations of touch, pressure, pain and temperature which it then localises to specific body regions. Controls opposite side of the body
• Wernicke’s area

  • Location - Posterior portion of the left temporal lobe
  • Responsibility/ role - understanding language
  • If damaged - Wernicke’s aphasia is experienced when they produce nonsense words
• Visual centres

  • Location - In the visual cortex in the occipital lobe at the back of the brain
  • Function - Spans both hemispheres, opposite. Different areas process different information
  • Visual processing function - Begins in the retina where light enters and strikes photoreceptors. Nerve impulses are transmitted to the brain via the optic nerve. The majority go to the thalamus which acts as a relay station and passes the info onto the visual cortex