13. The limbic system Flashcards
What is the limbic system?
A region of the cortex - a group of cortical and subcortical nuclei found on the medial aspect of the frontal, parietal and temporal lobes
What is the function of the limbic system?
Part of the brain which controls motivation, emotion and memory (learning)
Involved in pleasure, pain, motivation and memory
Is responsible for rewarding animals when they increase their chance of survival e.g. eating/sex or for punishing them when they decrease their change of survival e.g. injury causing pain
Which other major system in the brain is the limbic system greatly connected to?
Is connected to the olfactory system
Allows animals to experience good memories when they smell nutritious food etc
In humans, why some foods can make you hungry and others make you nauseous - other smells can trigger memories or make you feel sexy
Which anatomical regions of the brain is the limbic system composed of and where are these structures located?
Composed of the cingulate cortex (anterior and posterior regions), the orbito-frontal cortex and the parahippocampal cortex
The cingulate cortex is located superiorly to the corpus callosum - curves all the way around
The orbito-frontal cortex is inferior to the corpus callosum and anterior
SO the posterior cingulate continues on into the anterior cingulate which continues on into the orbito-frontal cortex
The parahippocampal cortex lies in the medial temporal lobe
What is the blood supply to the limbic system?
Blood supply is from the anterior cerebral artery (anterior region) and the posterior cerebral artery (posterior most region)
An infarct in either of these arteries can affect the limbic system
What are the divisions of the anterior cingulate cortex?
Rostral anterior cingulate (near the head, more anteriorly positioned)
Caudal anterior cingulate (near the tail)
What are the functions of the different parts of the anterior cingulate cortex?
Rostral anterior cingulate - less known but thought to be the region which is involved with which actions to take to deal with the pain
Caudal anterior cingulate - where we register the quality of the pain i.e. how bad it is on a scale of 1 to 10
What is cingulotomy and what is it thought to be useful for?
This is the procedure of cutting into the cingulate gyrus to disrupt the passing of the rostrocaudal fibres
This is thought to reduce the emotional distress of pain i.e. reduce the emotional impact of the pain
What is the function of the posterior cingulate cortex?
We do not really understand it’s function properly BUT believed to be involved in visuo-spatial memory i.e. finding your way around a new city, being able to read a map
What is the parahippocampal gyrus and where is it located?
This is a key part of the cortex involved with learning and memory
Lies medially and inferiorly in the temporal lobe - closely connected to the subcortical structures within the temporal lobe - surrounds the hippocampus
In which lobes are the following horns of the lateral ventricle:
Anterior horn
Posterior horn
Inferior horn
Anterior horn - frontal lobe
Posterior horn - occipital lobe
Inferior horn - temporal lobe
What is meant by ‘subcortical’?
Lying below the cortex
What are the subcortical parts of the limbic system?
Hippocampus
Amygdala
Accumbens nucleus
Septal nuclei
These lie around the walls of the inferior horn of the lateral ventricles in the temporal lobe
Where is the hippocampus located?
Hippocampus lies along the medial wall of the inferior horn of the lateral ventricle
What is the fornix and what is it’s path in the brain?
Fornix - collection of the axons leaving the hippocampus moving underneath the corpus callosum towards the hypothalamus
Ends in the mammillary body of the fornix