Localisation of function

• 1. Frontal Lobe – where the PFC is located, dysfunction in OCD patients and where episodic memories are connected to.
  2. Brainstem – commands to the ANS come from here
  3. Hippocampus – Memory  - H.M  
  4. Pineal – gland in the endocrine system responsible for releasing melatonin which regulates sleep
  5. Synapse – synaptic transmission 
  6. Hypothalamus – detects a threat and activates the fight or flight response 
  7. Dendrite – structure of a neuron
  8. Axon – structure of a neuron
  9.  ‘Cord spinal’ – Spinal cord – part of the CNS 
  10. Temporal lobe – episodic memories
  11. ‘Parietal’ – Parietal lobe semantic memories
• The localisation of brain function is the idea that different behaviours stem from a particular location in the brain. Areas of cortical specialisation are the places in the brain that are specifically responsible for functions. 
• Areas of the brain

  
• The brain is made of three concentric layers - the central core (the old brain) / the limbic system (intermediate brain) / the cerebrum (new brain).
• The Central Core

  • Involuntary behaviours: Sleeping, Digesting, Endocrine system
  • It includes structures such as the hypothalamus – the gland that activates the fight or flight response
  • The bottom part is the brain stem which is a control centre for the ANS
  • Maintains Homeostasis: the process by which the body maintains a constant physiological state
• The Limbic System

  • This controls our emotions. 
  • Around the central core of the brain, interconnected with hypothalamus.
  • Contains structures such as the hippocampus; key roles in memory.
• The cerebrum

  • The outer part of the brain that regulates our higher intellectual processes and is divided into 2 hemispheres, each with 4 lobes. 
  • The layer of grey matter, about 2 to 4mm thickness, on the outer surface of the cerebrum is called the cerebral cortex.
  • In humans, the cerebral cortex is densely packed with over 10 billion neurons and therefore, much of the neural activities of the cerebrum take place within this layer.
• Area of cortical specialisation

  
• Function / Area of Cortical Specialisation / Lobe

  • Voluntary movement / Motor cortex / Frontal
  • Sensory / Somatosensory cortex / Parietal
  • Visual / Visual cortex / Occipital
  • Auditory / Auditory cortex / Temporal
  • Speech production / Broca’s area / Left Frontal
  • Speech comprehension / Wernicke’s area / Left Temporal
• The Motor Cortex

  • The motor cortex is responsible for voluntary movements and is located in the rear of the frontal lobe.
  • Both hemispheres of the brain have a motor cortex, with the motor cortex on one side of the brain controlling the muscles on the opposite side of the body. 
  • Different parts of the motor cortex exert control over different parts of the body. These regions are arranged logically next to one another (the region that controls the foot is next to the region that controls the leg)
  • Damage to this area can result in a loss of control over movements. 
• The Somatosensory Cortex

  • This cortex detects sensory events arising from different regions of the body. It is located in the parietal lobe. 
  • Using sensory information from the skin, the somatosensory cortex produces sensations of touch, pressure, pain and temperature, which it then localises to specific body regions. 
  • Both hemispheres have a somatosensory cortex, with the cortex on one side of the brain receiving sensory information from the opposite side of the body. 
  • Damage to this area can cause an inability to recognise objects by touch. 
• Visual Cortex

  • The primary visual centre in the brain is located in the visual cortex, in the occipital lobe of the brain. However, visual processing actually begins in the retina with light.
  • The visual cortex is located in both hemispheres, with the right hemisphere receiving its input from the left visual field, and the left hemisphere receiving input from the right visual field. 
  • The visual cortex contains several different areas, with each of these areas processing different types of visual information, such as colour, shape or movement. 
  • Damage to the visual cortex can cause blindness.
• Auditory Cortex

  • The auditory area of the brain is located in the temporal lobe in both hemispheres and is responsible for performing functions in hearing. 
  • Sound waves are passed through the ear via the auditory canal and hit the eardrum. The waves are then converted to nerve impulses which travel through the inner ear to the central core and eventually reach the auditory cortex which brings the sound into awareness.  
  • The auditory cortex is composed of fields which are responsible for processing different types of sound.
  • Damage to the auditory cortex can cause an unawareness of sound.
• Fritsch and Hitzig - Located area for motor functions in dogs.

  Ferrier - Located area auditory function in monkeys.

  Penfield - Created maps for sensory and motor functions in humans.

  Panizza - Located area for visual function in stroke patients.

  Brown and Schafer - Located area for visual function in monkeys.
• Animal Research Support

  • The functions of the visual cortex were investigated at length by Hubel and Wiesel.
  • In the 1950s and 60s they conducted famous experiments on cats and discovered that single cells in the visual cortex would fire in response to lines at specific angles. 
  • This contributed greatly to the discussion of localisation of function and showed how our visual functions were distributed across the visual cortex.
• Human Research Support

  When H.M had his hippocampi removed he was unable to make new long-term memories. This suggests that transferring information to LTM are localised to specific areas of the brain (the hippocampus). However, as a case study is of one unique individual, they may not represent the wider population. In this case H.M had a history of epilepsy and subsequent brain damage from an operation. Therefore we need to be cautious generalising the findings to our understanding of localisation of brain function.
• Lashley

  All areas of the brain are EQUIPPED with the POTENTIAL to take over other functions. Patients who suffer from brain damage and lose a function, often can recover it because the brain recruits other areas to carry out that function. Rat studies show us that higher cognitive functions like problem solving seem to include lots of different areas. Therefore strict localisation is impossible.