Cerebral cortex

Question 1

Name and describe the 3 types of fibers in cerebral white matter.

Answer 1

1. Association fibres: connect areas within the same hemisphere
2. Commissural fibres: connect L hemisphere to R hemisphere eg corpus callosum (biggest)
3. Projection fibres: connect cortex with lower brain structures (eg thalamus, brainstem and spinal cord) eg. corticospinal tract)

Question 2

Describe the 6 cortical layers of grey matter

Answer 2

• Layers 1-3: cortico-cortical connections
• Layer 4: Input from thalamus
• Layers 5-6: Connections with subcortical, brainstem and spinal cord

Question 3

Describe the organisation of the neocortex (grey matter).

Answer 3

• Arranged in layers and columns
• Comprised of different lobes: Primary cortices and association cortices

Question 4

Label the primary and association cortices

Answer 4

Diagram

Question 5

Describe the differences between primary and association cortices

Answer 5

Primary cortices:

• function predictable
• organised topographically
• left-right symmetry

Association cortices:

• function less predictable
• not organised topographically
• left-right symmetry weak/ absent

Question 6

Describe the frontal, parietal and temporal cortex lesions.

Answer 6

• Frontal cortex lesions: characteristed by a lack of planning, behavior becomes disorganise, attention span and concentration diminish, self-control is hugely impaired
• Parietal cortex lesions: posterior parietal association cortex created a spatial map of the body in surroundings, from multi-modality function. injury may cause disorientation, inability to read maps, apraxia (inability to interact with env), hemispatial neglect
• Temporal cortex lesions: language object recognition, memory, emotion. injury leads to agnosia, receptive aphasia (failure to understand outside world)
• Visual association cortex: prosopagnosia

Question 7

What is hemispheric specialisation?

Answer 7

Patients who have had a callosotomy (no corpus calosum - in epileptic patients) have lateralised deficits in function

Question 8

Describe the following imaging scans:

• Diffusion tensor imaging
• TMS
• TDCS
• PET
• MED EEG

Answer 8

• Diffusion tensor imaging: tactography (shows integrity of functional pathways)
• TMS (transcranial magnetic stimulation): magnetic field induced electric current in cortex, causing neurons to fire -> used to test whether specific area in brain is responsible for function
• TDCS (transcranial direct current stimulation): changes the local excitability of neurones, increasing or decreasing the firing rate (doesn’t induce neuronal firing)
• PET (positron emission tomography): ligand into patient
• MEG (megnetoencephalograhy): measures magnetic fields
• EEG (electroencephalography): measures electric field
• fMRI

Question 9

How can we measure optimism?

Answer 9

measure the brain response to imaging positive and negative events in the future or the past