3.6 Limbic system anatomy and memory

Question 1

What is the limbic system composed of? (7 points)

Answer 1

Cingulate gyrus 
Parahippocampal gyrus
Septal area
Hippocampus and dentate gyrus 
Amygdala 
Hypothalamus 
Anterior thalamic nuclei

Question 2

The anterior thalamus relates information to which part of the limbic system?

Answer 2

First the cingulate gyrus. 
The cingulate gyrus relates information to the: 
1. Hippocampal formation 
2. Amygdala, and
3. The Septum 

These then project fibres elsewhere, then finally to the hypothalamus, which ends again in the anterior thalamus.

Question 3

What 4 parts compose the hippocampal formation?

Answer 3

Hippocampus
Dentate Gyrus
Parts of the parahippocampal gyrus
Subiculum

Question 4

What is the embryological origin of the hippocampus?

Answer 4

It is formed by infolding of the inferomedial part of the TEMPORAL LOBE into the inferior horn of the lateral ventricle.

Question 5

What is Sommer’s sector?

Answer 5

The CA1 region of the hippocampus (most lateral) that is +++ sensitive to hypoxia and die after a few minutes.

Question 6

Where does the hippocampus receive input from? (afferents) (3 points)

Answer 6

Inferior temporal cortex (adjacent to it)
Contralateral hippocampus (via fornix)
Brainstem nuclei

Question 7

Where does the hippocampus send outputs to? (Efferents)

Answer 7

Mamillary body of the hypothalamus via the fornix.

Question 8

Where does the hypothalamus receive input from? (4 points)

Answer 8

Visceral afferents
Hippocampus
Somatosensory afferents (esp erotogenic)
Input from septal area - responsible for basic emotional drives

Question 9

What are the efferents out of the hypothalamus?

Answer 9

To the anterior thalamus- Mamillothalamic fasciculus (largest bundle)
Vagal nuclei- parasympathetic
Interomediolateral cell column of spinal cord (sympathetic)
Sacral autonomic nucleus- Parasympathetic

Also thought to have role in memory acquisition, visceral manifestation of emotions

Question 10

What is the circuit of Papez?

Answer 10

It connects the hippocampus to the cingulate cortex via mamillary bodies of hypothalamus and anterior thalamus. 
Components: 
1. hippocampus 
2. fornix
3. mamillary body 
4. anterior thalamic nuclei 
5. cingulate gyrus 
6. parahippocampal gyri 

New memories require circuit of Papez to be intact in min. 1 hemisphere

Question 11

What are the inputs (afferents) into the amygdala?

Answer 11

1. Temporal cortex
2. Frontal cortex
3. Septum
4. Olfactory cortex
5. Brain stem

Question 12

What are the outputs of the amygdala?

Answer 12

1. Hypothalamus

2. Septal area

Question 13

What is the role of the amygdala?

Answer 13

Evaluating the significance of environmental events, and reinforcement

Question 14

What is Brodmann’s Cortical Map?

Answer 14

It is a map of 52 areas (like 52 weeks in a year) of the surface of the brain both lateral and medial.
It attempts to map out the functions of the various surface areas of the cerebral cortexes