Localisation of function in the brain

Question 1

Definition of Localisation of Function

Answer 1

• Localisation of Function: Refers to the theory that specific areas of the brain are responsible for particular physical and psychological functions.
• Key Concept: Different parts of the brain are specialized for different types of behaviours, processes, or activities.

Question 2

Hemispheric Lateralisation

Answer 2

• Hemispheric Lateralisation: The idea that the two hemispheres of the brain have different specialisations.
  o Left Hemisphere: Generally responsible for language, analytical, and logical tasks.
  o Right Hemisphere: More involved in creativity, spatial awareness, and visual tasks.

Question 3

Key Areas of the Brain - Cortexes

Answer 3

• Motor Cortex (Frontal Lobe):
  o Controls voluntary movement.
  o Damage can lead to loss of movement in specific parts of the body.
• Somatosensory Cortex (Parietal Lobe):
  o Processes sensory information such as touch, pain, and temperature.
  o The amount of cortex devoted to a body part corresponds to its sensitivity (e.g., hands have more).
• Visual Cortex (Occipital Lobe):
  o Processes visual information from the eyes.
  o Damage can result in blindness or difficulties processing visual information.
• Auditory Cortex (Temporal Lobe):
  o Responsible for processing auditory information from the ears.
  o Damage may lead to hearing loss or difficulties understanding sounds.

Question 4

Broca’s Area

Answer 4

• Location: Left frontal lobe, typically in the left hemisphere.
• Function: Involved in speech production.
• Broca’s Aphasia: Damage to Broca’s area leads to difficulty producing speech, though understanding remains intact.
  o Individuals can often understand language but have trouble speaking fluently (telegraphic speech).
  o Example: Patient “Tan,” who could only say “tan” after Broca’s area damage.

Question 5

Wernicke’s Area

Answer 5

• Location: Left temporal lobe, typically in the left hemisphere.
• Function: Responsible for language comprehension.
• Wernicke’s Aphasia: Damage results in fluent but nonsensical speech (word salad), and individuals struggle to understand spoken or written language.

Question 6

Case Studies Supporting Localisation

Answer 6

• Phineas Gage:
  o Suffered damage to his frontal lobe after an accident, resulting in significant personality changes.
  o Demonstrates the role of the frontal lobe in personality and behaviour regulation.
• HM (Henry Molaison):
  o Underwent surgery removing part of his hippocampus to treat epilepsy, resulting in severe memory impairment (anterograde amnesia).
  o Provided evidence that the hippocampus is vital for memory formation.

Question 7

Brain Scanning Techniques and Localisation

Answer 7

• fMRI (Functional Magnetic Resonance Imaging):
  o Measures brain activity by detecting changes in blood flow. Active areas during a task require more oxygen, so increased blood flow indicates the region’s involvement.
  o Supports localisation by showing specific brain areas activate for different tasks.
• PET Scans (Positron Emission Tomography):
  o Tracks radioactive substances to show areas of high activity, offering insight into which brain regions are responsible for particular functions.

Question 8

Criticism of Localisation Theory

Answer 8

• Lashley’s Equipotentiality Theory:
  o Argues that rather than specific areas being responsible for functions, the brain operates as a whole in processes like learning.
  o Lashley found that after damaging areas of rats’ brains, they could still learn mazes, suggesting that other parts of the brain can compensate for damaged areas.
• Plasticity:
  o The brain’s ability to reorganise itself by forming new neural connections after damage.
  o When one area is damaged, other areas can sometimes take over the lost functions, challenging strict localisation.

Question 9

Evaluation of Localisation of Function

Answer 9

• Strengths:
  1. Empirical Support: Broca’s and Wernicke’s areas have clear evidence supporting localisation through case studies of brain-damaged patients.
  2. Brain Imaging: Modern neuroimaging techniques like fMRI and PET scans provide objective, reliable evidence that certain areas of the brain are specialised for specific tasks.
• Limitations:
  1. Plasticity: Evidence of brain plasticity shows that functions aren’t entirely localised, as undamaged brain areas can sometimes compensate for damaged regions.
  2. Reductionist: Localisation theory simplifies the brain’s complexity by attributing specific functions to specific areas, overlooking the brain’s more holistic functioning.

Question 10

Key Exam Points for Localisation of Function

Answer 10

• Key Terms: Be able to define localisation of function, hemispheric lateralisation, and explain the role of different cortexes (motor, somatosensory, auditory, visual).
• Case Studies: Understand the significance of Phineas Gage, Broca’s patient Tan, and Wernicke’s aphasia for supporting localisation.
• Evaluation: Provide balanced evaluations, considering strengths like empirical support and limitations like plasticity and Lashley’s theory.
• Brain Areas: Accurately explain Broca’s and Wernicke’s areas, including their functions and associated disorders.