L2B - Neuroanatomy: History of Brain Mapping

Question 1

Brain can be divided into…

Answer 1

• Cerebrum (makes up the majority of the brain; including the cerebral cortex),
• Cerebellum (separate division located behind the brain stem)
• Brainstem

Question 2

Cerebrum (Cerebral Hemispheres):

Answer 2

Two Hemispheres, divided by Longitudinal Fissure or Inter-Hemispheric Fissure

Question 3

Cerebral Cortex:

Answer 3

Grey matter = The outermost surface layer of the cerebrum

• Surface of the brain 2 to 4 mm thick
• Contains the cell bodies of the brain’s neurons
• Highly folded to maximize surface area. i.e. maximize amount of cortex that can fit inside skull
  
  • ‘Hills’ are called “Gyrus”
  • ‘Valleys’ are called “Sulcus”
  • These are used as road markers for research to find the way around the brain

White matter: underneath the grey matter is all the “wiring” (i.e. axons of the neurons, connecting to the spinal cord and to other areas of the cortex). Covered in fat (Meilin Sheath)

Question 4

Anatomic terminology for directions/locations:

Answer 4

Question 5

Cerebral Cortex – functional areas

Answer 5

Question 6

Frontal Lobe:

Answer 6

Executive (reasoning, planning, problem solving, inhibitory control, memory) and motor functions

• Broca’s area = Speech coordination
• Insula cortex = Working memory
• Premotor cortex = Motor planning
• Primary motor cortex = Movement (motor execution)

Broca’s area

• Mechanical expression of speech;
• Damage: Intact comprehension but difficulty finding and expressing the right words (slow/non-fluent speech)

Question 7

Temporal Lobe:

Answer 7

Hearing, comprehension, emotion and memory formation

• Primary auditory cortex = Hearing
• Wernicke’s area = Language comprehension
  
  • Damage: Fluent, nonsensical speech due to inability to understand language
• Limbic system
  
  • Amygdala = Fear (conditioning) and arousal; Responds to threats/danger
  • Hippocampus = Forming new memories (damage results in anterograde (no new memories), episodic amnesia)

Question 8

Corpus callosum:

Answer 8

Connects hemispheres to allow communication

Question 9

Primary motor (anterior central sulcus) & sensory (posterior central sulcus) cortexes:

Answer 9

Cortex area size of body part is correlated to the degree of sensitivity or fine motor control

Question 10

Occipital lobe:

Answer 10

Visual perception and processing

• Primary visual cortex = Visual perception
• Higher visual areas = Process shape, colour, orientation, motion
• Fusiform gyrus = Facial perception (damage (prosopagnosia) results in inability to recognise familiar faces)
• Via inferior temporal lobe = Perception of objects for recognition
• Via parietal lobe = Perception of objects for directing actions

Question 11

Parietal lobe:

Answer 11

• Sensory perception
  
  • Primary somatosensory cortex = Perception of touch and pain
• Spatial attention (directing eye movements (attention) to explore visual world)
• Linking vision with actions (by providing spatial location of objects around us for guiding actions)

Question 12

Functional Brain Anatomy:

Answer 12

Specific functions can be localised to specific areas of the brain

Brain “mapping” = Identifying which part of the brain is responsible for a particular behaviour or function.

Question 13

Homunculus:

Answer 13

• Primary Sensory cortex and Primary Motor cortex
• Brain function “mapped” by electrical stimulation
• Brain stimulation leads to sensation or movement (muscle twitch)
• Size of area on cortex determines sensitivity or fine motor control

Question 14

Working Memory =

Answer 14

• Remembering a piece of information like a phone number for short periods of time
• Operation, eg. Maths
• Reading shows superior working memory