Cortical organisation and function

Question 1

What is gyri and sulci?

Answer 1

gyri are the folds/bumps
Sulci are the grooves/pits

Question 2

How is the cerebral cortex organised?

Answer 2

-Into lobes
-Layers
-Columns

Question 3

How is the cerebral cortex divided?

Answer 3

-divided into regions known as “brodmann areas”
-Based on cytoarchitecture (cell size, spacing/ packing density and layers)
-Areas shown to relate to function

Question 4

What are the lobes of the brain?

Answer 4

-Frontal lobe
-Parietal
-Temporal
-Occipital
-Insular cortex
-Limbic

Question 5

What is the function of the frontal lobe?

Answer 5

-Regulating and initiating motor function
-Language
-cognitive functions (executive function
[e.g. planning])
-attention
-memory

Question 6

What is the function of the parietal lobe?

Answer 6

Sensation - touch, pain
sensory aspects of language
spatial orientation and self-perception

Question 7

What is the function of the occipital lobe?

Answer 7

Processing visual information

Question 8

What is the function of the temporal lobe?

Answer 8

Processing auditory information
emotions
memories

Question 9

What is the function of the limbic lobe

Answer 9

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

Concerned with learning, memory, emotion, motivation and reward

Question 10

What is the function of the insular cortex

Answer 10

lies deep within lateral fissure
Concerned with visceral sensations (e.g. hunger/thirst) , autonomic control, and interoception, auditory processing, visual vestibular integration (e.g. motion sickness)

Question 11

What is the grey matter of the cerebral cortex?

Answer 11

neuronal cell bodies and glial cells – around 85 billion of each

Question 12

What is the white matter of the cerebral cortex?

Answer 12

Myelinated neuronal axons arranged in tracts

Question 13

What are the 3 type of fibres that run through the white matter tracts?

Answer 13

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

Question 14

What types of association fibres are there? what are their functions?

Answer 14

Short and long fibres:
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 15

What type of commissural fibres are there?

Answer 15

1. Corpus callosum
2. Anterior commissure

Question 16

What are the types of projection fibres?

Answer 16

-Afferent – towards cortex
-Efferent – away from cortex
-Deeper to cortex radiate as the corona radiata
-Converge through internal capsule between thalamus and basal ganglia

Question 17

What is the internal capsule

Answer 17

A white matter structure for transmission of information to and from the cerebral cortex

Question 18

what are the 2 types of cortices/ brodamann areas?

Answer 18

1. PRIMARY cortices
   Function predictable
   Organised topographically
   Symmetry between left and right
2. SECONDARY cortices:
   function less predictable
   not organised topographically
   left-right symmetry weak or absent

Question 19

What are the cortices of the frontal lobe? What type of information do they process?

Answer 19

Primary:
“primary motor cortex”
controls fine, discrete, precise voluntary movements.
Provides descending signals to execute movements.

Secondary: (there are 2)
1. “Supplementary”
Involved in planning complex movements (e.g.
internally cued)- like speech
2.”Premotor area”
involved in planning movements (e.g. externally cued)

Question 20

What are the cortices of the parietal lobe? What type of information do they process?

Answer 20

Primary:
“Primary somatosensory cortex”
processes somatic sensations arising from receptors in the body (e.g. fine touch, vibration, two-point discrimination, proprioception, pain and temperature.)

Secondary:
“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 21

What are the cortices of the occipital lobe? What type of information do they process?

Answer 21

Primary:
“primary visual”
Processes visual stimuli

Secondary:
“Visual association”
Gives meaning and interpretation of visual input

Question 21

What are the cortices of the temporal lobe? What type of information do they process?

Answer 21

Primary:
“Primary auditory”
processes auditory stimuli

Secondary:
“Auditory association”
Gives meaning and interpretation of auditory input

Question 22

What are the 3 other brodmann areas? what are they responsible for?

Answer 22

“Prefrontal cortex”
-attention
-adjusting social behavior
-planning
-personality expression
-decision-making

“Broca’s areas”
production of language

“Wernicke’s area”
Understanding of language

Question 23

What issues would a frontal lobe lesion cause?

Answer 23

-changes in personality
-Inappropriate behaviour

Question 24

What issues would a parietal lobe lesion cause?

Answer 24

-If lesion in one side/ hemisphere, it would cause issues on the opposite side
e.g. lesion in right hemisphere=
Contralateral neglect (neglect to the left side of body- not shaving the left side of face)
Lack of awareness of self on left side (not a visual defect)
Lack of awareness of left side of extrapersonal space

Question 25

What issues would a temporal lobe lesion cause?

Answer 25

-agnosia (inability to recognize)
-anterograde amnesia (Inability to form new memories)

Question 26

What issues would a lesion to the Broca’s area cause?

Answer 26

Expressive aphasia – poor production of speech, comprehension intact

Question 27

What issues would a lesion to the Wernicke’s area cause?

Answer 27

Receptive aphasia- poor comprehension of speech, production is fine

Question 28

What issues would a lesion to the Primary visual cortex cause?

Answer 28

blindness in the corresponding part of the visual field

Question 29

What issues would a lesion to the “visual association” area cause?

Answer 29

deficits in interpretation of visual information e.g. prosopagnosia: inability to recognise familiar faces or learn new faces (face blindness)

Question 30

What does a PET scan show?

Answer 30

“positron emission tomography”
Blood flow directly to a brain region
-increased blood flow indicative of increased activity in that area

Question 31

What does an fMRI show?

Answer 31

“Functional magnetic resonance imaging”
Amount of blood oxygen in a brain region

Question 32

What does an EEG show?

Answer 32

“Electroencephalography”
Measures electrical signals produced by the brain
The action potentials are fired from either:
a) visual stimuli
b) somatosensory activity (e.g. thalamic activity, Mid cervical cord activity

shows a series of waves that reflect sequential activation of neural structures along the somatosensory pathways

Question 33

What does MEG show?

Answer 33

“Magnetoencephalography”
Measures magnetic signals produced by the brain

Question 34

What is a TMS?

Answer 34

“Transcranial magnetic stimulation”
Process of:
-using electromagnetic induction to stimulate neurons
-to assess the functional integrity of neural circuits

Question 35

What is a tDCS?

Answer 35

“transcranial direct current stimulation”
uses low direct current over the scalp to increase or decrease neuronal firing rates

Question 36

What does a DTI show?

Answer 36

“Diffusion tensor image”
-imaging based on diffusion of water molecules

Question 37

What does a DTI with tractography show?

Answer 37

-3D reconstruction to assess neural tracts