Cortical Function

Question 1

Describe the functions responsible by the frontal lobes

Answer 1

• Motor - primary motor cortex on pre-central gyrus
• Expression of speech (usually left hemisphere)
• Behavioural regulation / judgement
• Cognition - higher thought
  
  • To test on patient, as them to count down by 7’s from 100
• Eye movements
• Continence - medial frontal lobe (motor homunculus of genitals and pelvic floor)

Question 2

Describe the functions responsible by the parietal lobes

Answer 2

• Sensory - primary somatosensory cortex on post-central gyrus
• Comprehension of speech (usually left hemisphere)
• Body image (usually right hemisphere)
  
  • Damage leads to neglect - fail to acknowledge left side of world exists
  • Eat right half of plate and not left, don’t know left half of body exists
• Awareness of external environment (attention)
• Calculation and writing
• Visual pathways projecting through white matter - superior optic radiations

Question 3

Describe the functions responsible by the temporal lobes

Answer 3

• Hearing - primary auditory cortex
• Olfaction - primary olfactory cortex on uncus
• Memory - hippocampus
• Emotion
• Visual pathways projecting through white matter - inferior optic radiations

Question 4

Describe the functions dominated by the left hemisphere

Answer 4

• Left hemisphere - sequential processing
• Language
• Mathematics/logic
• (Left hemisphere is dominant in 95% of people - explains why most people are right handed)

Question 5

Describe the functions dominated by the right hemisphere

Answer 5

• Right hemisphere - ‘whole picture’ processing
• Body image
• Visuospatial awareness
• Emotion
• Music

Question 6

Describe the corpus callosum

Answer 6

• A huge bundle of white matter connecting the two hemispheres
• An early surgical treatment for epilepsy was to cut the corpus callosum to prevent seizure activity from propagating through the whole brain
  
  • Allowed the brain and human to ‘think in two halves’ (split brain syndrome)

Question 7

Describe the language pathway in the brain

Answer 7

• Language pathways predominantly in left hemisphere
• Broca’s area (inferior lateral frontal lobe) involved in production of speech
  
  • Near motor cortex to allow movement to produce speech
• Wernicke’s area (superior temporal lobe) involved in interpretation of language
  
  • Near auditory cortex to take in speech
• Broca’s area and Wernicke’s area connected by arcuate fasciculus
  
  • Direction from Wernicke’s area to Broca’s area as interpret speech first and then produce speech

Question 8

Describe the pathway for repeating a heard word

Answer 8

• Primary auditory cortex picks up speech
• Wernicke’s area translates impulses from auditory cortex to Broca’s area
  
  • Turn vibrations into words
• Broca’s area transmits signal to motor cortex in order to speak
  - Turns words to motor movements

Question 9

State the pathway for speaking a written word

Answer 9

Visual cortex -> Wernicke’s area -> Broca’s area -> motor cortex

Question 10

State the pathway for speaking a ‘thought’

Answer 10

• Take information from cerebral cortex and interpreted in -
  Wernicke’s area
  Information sent to Broca’s area and then motor cortex

Question 11

Describe Wernicke’s aphasia

Answer 11

• Speech fluent - Broca’s area intact
• No interpretation and processing of speech - Wernicke’s area impaired
  - Do not understand what people say to them

Question 12

Describe Broca’s aphasia

Answer 12

• Interpretation and understanding of speech intact - Wernicke’s area intact
• Speech not fluent - Broca’s area impaired
  - Difficult to speak what they want to say

Question 13

Differentiate between declarative and non-declarative memory

Answer 13

• Declarative memory - explicit, facts

- Non-declarative memory - implicit, motor skills, emotions

Question 14

How is memory stored and consolidated

Answer 14

• Memory is thought to be stored in a relatively distributed fashion throughout large areas of the brain
  
  • Declarative memory stored in cerebral cortex
  • Non-declarative memory stored in cerebellum
• For a memory to be converted from short term memory to long term memory, it needs to be consolidated
  
  • Consolidation depends on emotional context, rehearsal, association
• Hippocampus is crucial for consolidating declarative memories - sends signals to cerebral cortex
• Cerebellum is crucial for consolidating non-declarative memories

Question 15

Describe what neuroplasticity is

Answer 15

• Neuroplasticity - the molecular and cellular mechanisms of memory
• Strengthens synapses - release more neurotransmitter, increase receptor number, increase fibre number