Histological Organisation of Cerebrum, Cerebellum and Meninges

Question 1

Click on Answer to view histological images of the meninges.

Answer 1

[Slide 1] [Slide 2] [Slide 3]

Question 2

Pyramidal neurons, a type of neuron found in various areas of the brain, primarily use the neurotransmitter ____(a)____ for excitation. They can also be inhibited by the neurotransmitter ____(b)____.

Answer 2

(a) glutamate
(b) GABA (Gamma-aminobutyric acid)

Question 3

The pyramidal cells are the major output neurons of the cerebral cortex, and usually have one apical axon towards the cortical surface and multiple basal dendrites. True or False?

Answer 3

False; they have one apical dendrite and multiple basal dendrites
[Histological slide: pyramidal cell]

Question 4

State the 6 layers of the cerebral cortex from superficial to deep, indicating the distinguishing features and/or main cell types of each.

Answer 4

1. Molecular (plexiform) layer: it is mainly composed of dendrites and axons of neurons from other layers, as well as horizontal cells of Cajal-Retzius and glial cells.
2. External granular layer: contains numerous small granule cells (a type of stellate cell) and small pyramidal cells; involved in sensory processing and associative functions.
3. External pyramidal layer: consists mainly of medium sized pyramidal cells; they carry short association outputs; also contains some stellate cells and cells of Martinotti
4. Internal granular layer: characterized by a high density of stellate neurons with a few small pyramidal neurons and cells of Martinotti; this layer is the main cortical input layer
5. Internal pyramidal layer: this layer predominantly contains large pyramidal cells; this layer is the main cortical output layer; it is hence most prominent within the motor cortex; the primary motor cortex contains a specific form of pyramidal cells called the cells of Betz
6. Multiform (fusiform) layer: consists mostly of fusiform cells and cells of Martinotti that project to the thalamus and other cortical areas

Question 5

What is the cortical module?

Answer 5

It is the functional unit of the cerebral cortex.

Question 6

State 6 characteristics of the cortical module.

Answer 6

1. It has 6 layers
2. Layer 4 is the main input layer
3. All cells in the column are activated by one feature of stimulation/modality
4. Layer 5 is the main output layer characterized by giant pyramidal cells of Betz
5. Neurons fire at the same frequency
6. There is lateral inhibition
7. There is vertical activation

Question 7

(a) Identify the slide: [Slide].
(b) Name the three distinct histological layers that can be observed from outermost to innermost.
(c) Name 6 cell types present within the tissue displayed.

Answer 7

(a) cerebellar crotex
(b) layers: (1) outer molecular layer, (2) Purkinje cell layer, (3) inner granular layer
(c) Purkinje cells, astrocytes, Golgi neurons, granular cell neurons, basket cell neurons

Additional images: [Slide 2] [Slide 3]

Further notes:
Basket cell neurons
☑ Basket cells are inhibitory GABAergic interneurons.
☑ Their branched axonal arborizations give them their name, as they appear like baskets surrounding the soma of the target cell.
☑ Basket cells form axo-somatic synapses, directly controlling the action potential discharge rate of target cells.
☑ Basket cells can be found in various brain regions, including the cortex, hippocampus, amygdala, basal ganglia, and cerebellum. In the cerebellum, basket cells are located in the basal 1/3 of the molecular layer. Their inhibitory function helps fine-tune information processing in the brain.