Limbic system

Question 1

Define diencephalon.

Answer 1

-Thalamic structures: thalamus, hypothalamus, epithalamus and subthalamus

Question 2

Label the following.

Answer 2

Question 3

• Groups within the basal ganglia (terminology).. Define:
  
  • Lentiform nucleus
  • Striatum
  • Corpus Striatum

Answer 3

• Lentiform nucleus :
  > Putamen and globus pallidus
• Striatum
  > Caudate nucleus and putamen
• Corpus Striatum
  > Striatum and globus pallidus (OR caudate, globus, putamen)

Question 4

What is the thalamus?

Answer 4

• Grey matter protruding into 3rd ventricle
• Receives nearly all sensory info on its way to cerebral cortex integrates info and directs to
• Motor involvement (mainly with basal ganglia and cerebellum)
• Involved in emotional and memory functions (works with limbic system)

Question 5

What is the limbic system?

Answer 5

• A system of interconnected subcortical structures within the brain forming a ring around the corpus callosum.
  -Associated with producing behavioural and emotional responses.
• OLD

Question 6

5 Fs and limbic system.

Answer 6

• Feeling
• Fighting
• Fleeing
• Feeding
• Physical act of love

Question 7

List Functions of the limbic system (4 categories).

Answer 7

1- Emotions and drives - amygdala (Feelings, motivation etc.)
2- Homeostasis and motivation via hypothalamus (autonomic and neuroendocrine responses)
3- Olfaction - olfactory cortex
4- Memory formation via hippocampus (learning)

Question 8

What are the parts of the limbic system?

Answer 8

1- Cingulate Gyrus

2- Fornix: connecting pathway between hippocampus and mammillary body

3- Hippocampus: Receives information from all sensory association areas.

4- Amygdala: Structure that provides an emotional component to experiences and memory.

5- Mammillary Body: (linked to hypothalamus)

6- Olfactory Bulb

7- Parts of the thalamus and the hypothalamus

8- Entorhinal cortex - Relays major cortical input from the medial entorhinal cortex (MEC) and the lateral entorhinal cortex (LEC) > Hippocampus

Question 9

What is the function of the hypothalamus?
Where is it situated?

Answer 9

• Homeostasis
  -Numerous nuclei that have afferent and efferent connections with widespread regions of the NS
  > Releases factors acting on the pituitary gland
  > produces ADH (supraoptic nucleus)
  > Produces oxytocin (paraventricular)
• Most ventral (anterior) part of diencephalon
  > Lies beneath the thalamus and ventromedial to the subthalamic nucleus

Question 10

Where is the fornix, what is its function?

Answer 10

• Arch shaped bundle of fibres, travels over the diencephalon
• Output of hippocampus

Question 11

What is the function of mammillary bodies?

Answer 11

• Involved in memory formation
• Part of hypothalamus

Question 12

Where is the hippocampus found, what is its function?

Answer 12

• Found in temporal lobe
• Essential in memory consolidation & learning
• Receives information from all sensory association areas

Question 13

Where is the amygdala found? What is its function?
It is the main output to….. via……?

Answer 13

• Lies near temporal pole at the tip of the tail of the caudate nucleus.
• Provides an emotional component to experiences & memory, and the ability to recognise fear in others
  > Has extensive connections with all cortical association areas allowing us to associate emotions to what we sense e.g. see
• Main output to hypothalamus via stria terminalis

Question 14

What is different about the olfactory system?

Answer 14

1. No thalamic relay. Central projection of olfactory structures reach parts of the temporal lobe and amygdala without thalamic relay
2. The olfactory nerve consists of numerous bipolar neurones, whose cell bodies do not form a ganglion
3. Primary neurones are continually replaced: 30-120 days in mammals.

Question 15

Describe the following olfactory deficits.

1. Hyposmia
2. Dysosmia
3. Anosmia

Answer 15

1. Hyposmia (reduced)
2. Dysosmia (distorted)
3. Anosmia (Complete)

Question 16

What are the 3 association cortices?

What is their function? How describe the process.

Answer 16

• Prefrontal
• Inferior temporal
• Parietal-temporal-occipital

> Integrate information from different receptors or sensory areas and relate the information to past experiences.
- Different modalities combine
- Ability to deal with external stimuli or internal motivation
- Identify their significance
- Planning occurs
- Things are remembered

Question 17

What do all limbic components project into?
What is the limbic system a link between?

Answer 17

• Hippocampus

-Higher ‘neocortical’ goal directed behaviour to more primitive instinctive behaviour