Task 4 - Cerebral cortex

Question 1

The 5 different lobes

Answer 1

Frontal, parietal, temporal, occipital and limbic

Question 2

Neocortex

Answer 2

The part of human cortex that has 6 layers. Most of the human cortex is neocortex.

Question 3

Paleocortex

Answer 3

The part of the cortex in the olfactory bulb that has only 3 layers.

Question 4

Archicortex

Answer 4

The part of the cortex in the hippocampus that has only 3 layers.

Question 5

Allocortex

Answer 5

Paleocortex + Archicortex

Question 6

2 major cell types in the cortex

Answer 6

Pyramidal neurons: Found in layers III & V, their axons project out of the cortex to other regions of the brain & spinal cord, making them the main output cells

Granular/stellate neurons: Found in layers II and IV, remain within the cortex, they are the main interneurons.

Question 7

Molecular layer

Answer 7

Layer 1 of the cortex, contains mostly neuronal processes

Question 8

Multiform layer

Answer 8

Layer VI, contains output neurons of varying shapes & sizes

Question 9

The 6 Layers

Answer 9

1. Molecular layer (I)
2. External granular layer (II)
3. External pyramidal layer (III)
4. Internal granular layer (IV)
5. Internal pyramidal layer (V)
6. Multiform layer (VI)

Different cortical areas have different distributions of cells in all layers

Question 10

Holistic vs. localization paradigm of brain function

Answer 10

A debate in the dawn of neurophysiology between the following 2 positions:
Holistic - the entire cortex has roles in the execution of any brain function
Localization - functions are localizable to specific cortical areas

Question 11

Brodmann’s map of the human cortex

Answer 11

A drawing of a lateral & medial view of a human brain, displaying the segregation of
the cerebral cortex into 43 cortical areas belonging to 11 regions.

Question 12

Axoplasmic transport

Answer 12

The process responsible for movement of organelles (mitochondria), lipids, proteins, synaptic vesicles, and other parts of the cell membranes to and from the soma down to the axon to the synapses and back to the soma.

Question 13

Microtubule

Answer 13

Run along the length of the axon and provide the main cytoskeletal
tracks for transportation

Question 14

Kinesin and dynein

Answer 14

Motor proteins that move cargo in the anterograde (from soma to axon tip) and
retrograde (backwards to the soma) directions, respectively

Question 15

Association fibers

Answer 15

Fibers that interconnect cortical areas within 1 cerebral hemisphere

Question 16

Commissural fibers

Answer 16

Fibers that connect cortical areas in one hemisphere with the same areas in the other hemisphere, enabling coordination of cortical activity across the hemispheres

Question 17

Ascending & descending projection fibers

Answer 17

Fibers that travel to or from cortex to connect it with more caudal CNS areas (thalamus, basal ganglia, brainstem, spinal
cord).

Question 18

Types of Association fibers

2

Answer 18

1. Short assocation fibers: Connect areas in adjacent gyri, facilitating activity along a gyrus or sulcus.
2. Long association fibers: Connect more distant areas

Question 19

Types of Long association fibers

2

Answer 19

1. Superior longitudinal fasciculus (includes arcuate fasciculus)
2. Inferior occipitofrontal fasciculus (includes uncinate fasciculus)
3. Superior occipitofrontal fasciculus
4. Cingulum

Question 20

Superior longitudinal fasciculus

Answer 20

• Provides important sensory communication between the parietal, occipital and temporal lobes and the frontal cortex so that appropriate action can be performed.
• Includes arcuate fasciculus which connects the 2 language areas with each other in the language-dominant hemisphere

Question 21

Inferior occipitofrontal fasciculus

Answer 21

• Below the insula, connects frontal, temporal, and occipital cortices.
• Fibers that hook around the margin of the lateral fissure and connect the frontal and temporal lobes are called the uncinate fasciculus

Question 22

Superior occipitofrontal fasciculus

Answer 22

Runs adjacent to the corpus callosum and connects the frontal, parietal and occipital lobes.

Question 23

Cingulum

Answer 23

Located deep within the cingulate & parahippocampal gyri (a.k.a. limbic lobe of the limbic system), connects limbic cortex areas (a.k.a. areas overlying the limbic system structures) with each other

Question 24

Types of commissural fibers

3

Answer 24

1. Corpus callosum
2. Anterior commisure
3. Posterior commisure

Question 25

Subsections of corpus callosum

2

Answer 25

1. Splenum: The posterior pole
2. Genu: The anterior pole

Question 26

Corpus callosum

Answer 26

The largest commissural bundle, which lies deep in the interhemispheric fissure, connecting the 2 parietal lobes, and the 2 posterior frontal lobes with each other

Question 27

Anterior commissure

Answer 27

A small bundle of fibers that connects the anterior temporal lobes & the olfactory bulbs with each other

Question 28

Posterior commissure

Answer 28

Located in the midbrain, connecting the 2 pretectal nuclei.

Question 29

Projection fibers

Answer 29

Projection fibers come from all parts of the cortex in the corona radiata and converge
into a compact bundle called the internal capsule

Question 30

Internal capsule

Answer 30

A V-shaped (in horizontal section) bundle, which can be divided into several parts:

1. Anterior limb: Between the caudate and the lenticular nucleus (putamen + globus
   pallidus).
2. Posterior limb: Between the thalamus and the lenticular nucleus.
3. Genu: Where the 2 limbs meet.

Question 31

Default-mode network

Answer 31

• Network of brain regions that are active when an individual is at rest and not focused on the outside or engaged in tasks. It’s often referred to as the brain’s “resting state” network because it becomes more active when the mind is wandering or engaging in internally focused tasks like self-reflection etc.
• Key brain regions involved in the default mode network are:
  The medial prefrontal cortex (mPFC), posterior cingulate cortex (PCC), precuneus, inferior parietal lobule (IPL), and medial temporal lobe (MTL)

Question 32

Salience network

Answer 32

• Important for monitoring the saliency of external inputs and internal brain events.
• Anchored in the frontoinsular (FI) cortex (anterior insula) and dorsal anterior cingulate cortex (dACC) and is extensively connected with subcortical and limbic structures involved in reward and motivation

Question 33

Central executive network

Answer 33

• The central executive network is engaged during tasks that require focused attention, working memory, decision-making, problem-solving, and cognitive control
• Key brain regions associated with the central executive network include the dorsolateral prefrontal cortex (DLPFC), anterior cingulate cortex (ACC), and parts of the parietal cortex