Cortical Organisation and Function

Question 1

Describe the microscopic organisation of the cortex

Answer 1

It is organised into layers and columns, where layers consist of a molecular layer at the surface and multiform layer most deeply with alternating granular and pyramidal layers in between. Also consists of cortical columns.

Question 2

What is the Brodmann classification?

Answer 2

It is a classification based on cytoarchitecture - cell size, spacing or packing density and layers. Many areas are shown to relate to certain functions.

Question 3

What are the 5 functions of the frontal lobe?

Answer 3

Regulating and initiating motor function, Language, Cognitive Functions (exec functions like planning), Attention and Memory.

Question 4

What are the 4 functions of the parietal lobe?

Answer 4

Touch and pain sensation, sensory aspects of language, spatial orientation and self-perception

Question 5

What are the functions of the temporal and occipital lobes?

Answer 5

Temporal - processes auditory information, emotions and memory
Occipital - processes visual information

Question 6

What are the roles of the limbic lobe?

Answer 6

Concerned with learning, memory, emotion, motivation and reward
REMML

Question 7

What are the parts of the limbic lobe?

Answer 7

Includes the amygdala, hippocampus, mamillary body, and cingulate gyrus

Question 8

What is the insular cortex?

Answer 8

It lies lies deep within lateral fissure. It is concerned with visceral sensations, autonomic control, and interoception, auditory processing, visual-vestibular integration.

VIVAA

Question 9

What are the 3 types of white matter tracts?

Answer 9

1. Association fibres - connect cortical areas within same hemisphere.
2. Commissural fibres - connect homologous structure in left and right hemispheres
3. Projection fibres - connect cortex with lower brain structures (e.g. thalamus, brain stem and spinal cord)

Question 10

What are the 4 association fibres?

Answer 10

1. Superior Longitudinal Fasciculus connects frontal and occipital lobes
2. Arcuate Fasciculus - connects frontal and temporal lobes
3. Inferior Longitudinal Fasciculus - connects temporal and occipital lobes
4. Uncinate Fasciculus - connects anterior frontal and temporal lobes

Question 11

What are the 2 types of commissural fibres?

Answer 11

Corpus callosum and anterior commissural fibres

Question 12

How are projection fibres named?

Answer 12

Afferent fibres are those that move towards cortex. Efferent fibres are those that move away from cortex.

Question 13

What are examples of projection fibres?

Answer 13

The corona radiata radiates deep to cortex and then converges through internal capsule between thalamus and basal ganglia.

Question 14

How is localisation of function different between primary and secondary/association cortices?

Answer 14

Primary cortices have predictable function, topographical organisation and symmetry whereas all of this is absent with secondary.

Question 15

Compare functions of primary motor cortex of frontal lobe with suplementary and premotor areas

Answer 15

Primary motor cortex - Controls fine, discrete, precise voluntary movements. Provides descending signals to execute movements.
Supplementary - Involved in planning complex movements (e.g. internally cued)
Premotor - involved in planning movements (e.g. externally cued)

Question 16

Compare functions of primary somatosensory cortex of parietal lobe with somatosensory association

Answer 16

Primary somatosensory - processes somatic sensations arising from receptors in the body (e.g. fine touch, vibration, two-point discrimination, proprioception, pain and temperature.
Somatosensory association - Interpret significance of sensory information, e.g. recognizing an object placed in the hand. Awareness of self and awareness of personal space.

Question 17

Compare functions of primary visual cortex of occipital lobe with visual association

Answer 17

Visual cortex - processes visualstimuli

Visual association cortex - gives meaning and interpretation of visual input

Question 18

Compare functions of primary auditory cortex of temporal lobe with auditory association

Answer 18

Auditory cortex - processes auditorystimuli

Auditory association - Gives meaning and interpretation of auditory input

Question 19

What are the 5 roles of the prefrontal cortex?

Answer 19

Attention, Adjusting social behaviour, Planning, Personality expression, Decision Making

PAPAD

Question 20

What is Broca’s and Wernicke’s Area and where are they?

Answer 20

Broca’s Area is located unilaterally in the frontal lobe. It is responsible for production of language. Wernicke’s is found in the left temporal lobe. It is responsible for understanding of language.

Question 21

What is the consequence of a frontal lobe lesion?

Answer 21

Changes in personality and inappropriate behaviour.

Question 22

What is the consequence of a parietal lobe lesion?

Answer 22

Contralateral neglect occurs - lack of awareness of opposite side of body and extrapersonal space.

Question 23

What is the consequence of a temporal lobe lesion?

Answer 23

Leads to agnosia which is an inability to recognise. A medial temporal lobe lesion leads to anterograde amnesia (inability to form new memories).

Question 24

What is the consequence of lesions to Broca’s and Wernicke’s areas?

Answer 24

Broca’s and Wernicke’s are connected via the arcuate fasciculus. A lesion in Broca’s leads to expressive aphasia - poor production of speech, comprehension intact. A lesion in Wernicke’s leads to receptive aphasia - poor comprehension of speech, production is fine.

Question 25

What is the consequence of an occipital lobe lesion?

Answer 25

If in the primary visual cortex, leads to blindness in the affected visual fields. If in the visual association cortex, deficits in interpretation of visual information e.g. prosopagnosia: inability to recognise familiar faces or learn new faces (face blindness).

Question 26

How is cortical functioning radiologically assessed?

Answer 26

PET scanning helps assess blood flow to the brain region. Functional magnetic resonance imaging (fMRI) measures blood oxygen in a particular region. Both can be used to see which brain areas are active in a subject performing a task.

Question 27

How is encephalography used?

Answer 27

Electroencephalography measures electric signals produced by the brain while magnetoencephalography measures the magnetic signals produced by the brain. Helps measure event-related potentials generated.

Question 28

How can encephalography be used to detect entire somatosensory pathway?

Answer 28

Series of waves that reflect sequential activation of neural structures along the somatosensory pathways
used. Stimulation measured at different points.

Question 29

What is transcranial magnetic stimulation?

Answer 29

Used to assessthefunctionalintegrity of neural circuits using electromagnetic induction to stimulate neurons.

Question 30

What is transcranial direct current stimulation (tDCS)?

Answer 30

Uses low direct current over the scalp to increase or decrease neuronal firing rates

Question 31

What are 2 imaging methods of neural pathways?

Answer 31

Diffusion tensor imaging (DTI) is based on the diffusion of water molecules and if done with tractography can be used to create a 3D reconstruction to assess neural tracts.