Cerebral cortex

Question 1

Organisation of grey and white matter of the brain

Answer 1

Grey matter: on the surface of the brain. Nerve cell bodies. (cerebral cortex)

White matter: the circuitry (axons and connections).

Question 2

Types of fibres cerebral white matter contains

Answer 2

3 types of connections
Fibre relate to the connections

1. Association fibres: connect areas within the same hemisphere – local circuitry
2. Commissural fibres: connect left hemisphere to right hemisphere
3. Projection fibres: connect cortex with lower brain structures (e.g. thalamus), brain stem and spinal cord

Question 3

Neocortex

Answer 3

Part of the cerebral cortex involved in higher functions

Question 4

Organisation of neocortex

Answer 4

6 layers, but also cortical columns (basis for topographical organisation- similar neurones connected in the same column)

Layers 1-3- have mainly cortico-cortical connections

Layer 4- receives input from the thalamus

Layers 5 and 6- have connections with subcortical (e.g basal ganglia) , brain stem and spinal cord

Question 5

Lobes of the neocortex- what primary cortex they contain and its location

Answer 5

Occipital- Primary visual cortex

Parietal- primary somatosensory cortex in post central gyrus

Temporal- auditory cortex in the superior temporal gyrus

Frontal- primary motor cortex- part of the pre-central gyrus

Question 6

Function fo occipital lobe

Answer 6

Visual association cortex analyses different attributes of visual image in different places. The form & colour is analysed along the ventral pathway; spatial relationships & movement along dorsal pathway.

Question 7

Injury to occipital lobe

Answer 7

Lesions affect specific aspects of visual perception.

Question 8

Function of parietal lobe

Answer 8

Posterior parietal association cortex creates spatial map of body in surroundings, from multi-modality information.

Question 9

Parietal lobe lesion causes

Answer 9

Injury may cause disorientation, inability to read map or understand spatial relationships, apraxia (diifuclty in performing motor functions on command) , hemispatial neglect (only draw half of something).

Question 10

Function of temporal lobe

Answer 10

Language, object recognition, memory, emotion.

Question 11

Temporal lobe lesion causes

Answer 11

Injury leads to agnosia (inability to process sensory input) , receptive aphasia (difficulty with language or speech)

Question 12

Function of frontal lobe

Answer 12

Judgement, foresight, personality, appreciation of self in relation to world

Question 13

Frontal lobe lesion causes

Answer 13

Lesion leads to deficits in planning and inappropriate behaviour

Question 14

Difference in primary and association cortices

Answer 14

In primary cortices- function is predictable, organised topographically, left-right symmetry

In association cortices- less predictable function, not organised topographically and left-right symmetry is weak/absent

Question 15

Association areas

Answer 15

Speech areas: Broca’s area (inferior frontal lobe), Wernicke’s area (junction between parietal/temporal)
These areas are specific, but they are lateralised to the left hemisphere

Anterior to the PMC in the frontal lobe are the motor association areas (pre-motor cortex)

In the parietal cortex, we have parietal association areas
This is where integration occurs of multiple sensory modalities

There are auditory association areas immediately adjacent to the primary auditory cortex

Question 16

What does a lesion in the visual posterior association area cuase

Answer 16

Prosopagnosia- face blindness (inability to recognise or learn new faces)

Question 17

Hemispheric specialisation

Answer 17

The left hemisphere is language dominant, the right hemisphere is largely spatial processing.

Question 18

What impairment occurs to patients born without corpus callosum or who have had callosotomy

Answer 18

This means their hemispheres are divided and are unable to send information to each other

This causes the patient to have impaired processing.

This is shown in the experiment where if an image is shown on the right hand side they are able to say what they saw (since left hemisphere is verbal dominant)
However if shown on left hand side they are unable to say what they saw but are able to draw it (right hemisphere is spatial dominant).
This is due to the dominant activities on either hemisphere

Question 19

Diffusion tensor imagine (DTI)

Answer 19

DTI measures alignment of water molecules – coincident alignment is taken to mean fibre connectivity

This way, you can build up a fibre network of the brain

We can use DTI in brain tumour patients to show break down of such connections

Question 20

Transcranial magnetic stimulation

Answer 20

The magnetic field induces an electric current in the cortex, causing neurons to fire. This can be used to test whether a specific brain area is responsible for a function

Question 21

Transcranial direct current stimulation (TDCS)- and what it could be used to treat

Answer 21

Uses constant, low direct current delivered via electrodes on the head.
This does not directly induce neuronal firing). However, it changes the threshold for decreasing/increasing the firing rate.

Recent research suggests that TDCS could be used to reduce motion sickness by suppressing the area of the cortex associated with processing vestibular information. It may be a potential treatment for vertigo.

Question 22

PET scan

Answer 22

Shows activity in the brain
And can be used to show injuries to the brain
Has also allows to look at potential us of psychedelic drugs

Question 23

Magnetoencephalography and Electroencephalography

Answer 23

MEG- measures magnetic fields using a large machine

EEG- measures electric fields using lots of electrodes

Shows activity in the brain

Question 24

Functional MRI

Answer 24

Get information in vivo about connectivity (particularly in CNS conditions)

This is usually about monitoring blood flow and glucose metabolism

Where there is more glucose and more blood flow, there is probably higher activity