Cerebral cortex

Question 1

What is the neocortex?

Answer 1

Area of the cerebrum with 6 layers of cells, covering thebulk of the hemispheres.

Question 2

What are cell types make up the 6 layers of the cortex? What neuronal communication do they provide?

Answer 2

1. Cortico-cortical | Neuropil
2. Cortico-cortical | Pyramidal cells
3. Cortico-cortical | Pyramidal cells
4. Thalamic input | Stellate neurones
5. Connections to subcortical/brainstem/cord | Pyramidal neurones (axons leave cortex)
6. Connections to subcortical/brainstem/cord

Question 3

How is the cortex arranged vertically?

Answer 3

Dense columns - neurones with similar properties grouped into columns - providing the basic for topographic organisation.

Question 4

DIagram to show cortical areas and relevant processes.

Answer 4

Question 5

How do primary and association cortices differ?

Answer 5

Primary - topographical organisation + left/right symmetry.

Association - no topographical organisation. Left/right symmetry absent. Cerebral cortex outside the primary areas.

Question 6

What are the primary cortices? What areas of the brain are they associated with?

Answer 6

Primary motor (frontal)

Primary somatosensory (parietal)

Visual (occipital)

Auditory (temporal)

Gustatory (taste - temporal)

Olfactory (smell - temporal)

Question 7

List the association cortices and give their roles.

Answer 7

Motor association (skeletal muscle movement and motor planning)

Sensory association (sensory from skin, MSK, viscera and taste buds)

Visual association (vision)

Auditory association (hearing)

Prefrontal association (coordinates info from other areas and some behaviours/personality)

Question 8

What are association fibres. What is their role?

Answer 8

short fibres that run between adjacent parts of the cortex - connecting areas within same hemisphere

Question 9

What are commissural fibres? What is their role?

Answer 9

Connect left to right hemisphere (biggest is corpus callosum, with smaller anterior and posterior pathways)

Question 10

What is the role of projection fibres?

Answer 10

connect cortex with lower brain structures such as thalamus, stem and cord

Question 11

Identify association, commisurial and projection fibres.

Answer 11

Question 12

What is hemispheric specialisation? How do the left/right hemispheres specialise when this occurs?

Answer 12

Split brain lateralised defects.

Left hemisphere - language dominant

Right hemisphere - spacial processing

Question 13

What parts of the cerebral cortex are linked to speech?

Answer 13

Broca’s and Wernicke’s area.

Question 14

What is diffusion tensor imaging? explain it.

Answer 14

structural imaging using movement of water molecules in the brain to infer underlying white matter structure and hence pathways/connections - shows integrity of functional pathways

Question 15

What is transcranial magnetic stimulation? Explain it.

Answer 15

magnetic field used to induce electric current in cortex, causing neurones to fire - can test specific areas for function.

Question 16

What is transcranial direct current stimulation? Explain it.

Answer 16

neuromodulation via low direct current via electrodes on the head.

Change local neurone excitability to change firing rate. No direct induction of neurones.

Question 17

What is PET scanning. Explain it.

Answer 17

positron emission tomography - uses radioactive tracer molecules to locate brain areas where particular molecules such as dopamine are being absorbed to the brain - has good spatial resolution and specificity

Question 18

What is magnetoencephalopgrahy?

Answer 18

measures magnetic fields - mapping brain activity by recording fields produced by natural electrical currents

Question 19

What is electroencephalography?

Answer 19

electrophysiological monitoring method to record electrical activity - using electrodes placed on scalp or invasive electrodes during neurosurgery

Question 20

explain fMRI.

Answer 20

functional MRI - measure brain activity by detecting changes associated with blood flow.

(coupled with neurone activation).

Question 21

List the lobes of the neocortex.

Answer 21

Occipital. Parietal. Temporal. Frontal.

Question 22

What deficits are associated with damage to each lobe?

Answer 22

Occipital: visual perception

Parietal: disorientation, inability to map read, apraxia, hemispatial neglect

Temporal: agnosia, receptive aphasia

Frontal: planning deficits and inappropriate behaviour

Visual posterior association area: prosopagnosia (cannot recognise or learn new faces)

Question 23

What is the function of the occipital lobe?

Answer 23

visual association cortex - analyses attributes of visual image,

form/colour along ventral pathway and spatial relationships/movement along dorsal pathway.

Question 24

What is the role of the parietal lobe?

Answer 24

posterior parietal association cortex - creates spatial map of body in surroundings from many information modalities

Question 25

What is the role of the temporal lobe?

Answer 25

Language, object recognition, memory, judgement.

Question 26

What is the role of the frontal lobe?

Answer 26

judgement, foresight, personality, appreciation of self.