8.1.1 The cerebral Cortex

Question 1

What is the fine structure of the cerebral cortex?

Answer 1

6 layers containing cell bodies and dendrites

Question 2

What are most outputs from the cortex?

Answer 2

Axons of pyramidal neurones e.g. UMNs in primary motor cortex are pyramidal neurones

Question 3

What can outputs from the cortex be?

Answer 3

• Projection fibres going down to brainstem and cord
• Commissural fibres going between hemispheres
• Association fibres connecting nearby regions of cortex in same hemisphere (arcuate fasciculus)

Question 4

Where are most inputs from?

Answer 4

Thalamus and other cortical areas

Question 5

Where are most outputs from?

Answer 5

Pyramidal cells

Question 6

What functions are affected with cortical damage of the frontal lobe?

Answer 6

• Higher cognition
• Impulse control and social- damage leads to impulsive, disinhibited behaviours e.g. sexual inappropriateness and agression
• Voluntary motor control- contralateral weakness
• Speech- Broca’s area is here, can result in expressive dysphasia
• Eye movements- contains the frontal eye fields, conjugate gaze
• Continence- contains paracentral lobules (responsible for continence maintenance)

H- Higher cognition
I- impulse and social control
V- voluntary motor control
Extremely - eye movements
Serious - speech
Shit - continence

Question 7

What functions are affected with parietal lobe damage?

Answer 7

• Sensory- contains PSC, may lead to contralateral anaesthesia affecting all modalities (converge at cortex)
• Comprehension of speech- contains part of Wernicke’s area, damage to left parietal lobe can cause receptive dysphasia
• Body image and awareness of external environment - damage to right parietal lobe can cause neglect, in and outside the body
• Calculation and writing- works with frontal lobe to perform these tasks, can affect calculation ability but may also be frontal lobe
• Superior optic radiations pass through here

STEMI
Sensory
Talking
Eyes
Maths
Image

Question 8

What functions are effected with temporal lobe damage?

Answer 8

Taste
Emotion- contains limbic structures e.g. hippocampus and amygdala, lesions are complex but may be related to pathogenesis of some psychiatric disorders
Memory- hippocampus crucial for consolidating declarative memories, two hippocampi one in each lobe
Petrous- (Hearing), primary auditory cortex sits on superior surface of temporal near to wernickes area, may also cause auditory hallucinations
Olfaction- primary olfactory cortex sits on inferio-medial aspect, uncus
R-Adiations- inferior optic radiations
Language

TEMPORAL

Question 9

What can cause deja vu?

Answer 9

Temporal lobe epilepsy can trigger memories leading to a feeling of deja vu

Question 10

Where do inputs arise from?

Answer 10

Population of inputs arise from the reticular formation, maintaining cortical activation (conciousness)