Limbic System Flashcards
What are the main functions of the limbic system, the amygdala and the hippocampal formation?
- Control of memory and emotion
- coordination of some autonomic responses
- the amygdala controls emotions
- the hippocampal formation is involved with formation of memories, specifically short-term
What are the following structures?
What is significant about their relationship with the limbic system?
The olfactory tract is involved with the limbic system
smell can trigger emotions, memories and autonomic nervous system responses
the olfactory bulb and olfactory tract are outgrowths of the telencephalon - olfaction is the only sensory system to bypass the thalamus on the way to the cerebral cortex
What are the following structures?
What is the isthmus?
A narrowing of the cingulate gyrus where it is continuous with the parahippocampal gyrus
What is the uncus?
The parahippocampal gyrus hooks upon itself anteriorly to form a bump called the uncus
Where is the cingulate gyrus located?
Below the cingulate sulcus and above the corpus callosum
What is meant by HOME to remember the limbic structures?
H - Homeostasis
- performed by the hypothalamus
- e.g. blood pressure, heart rate, production and release of hormones
O - Olfaction
- paraolfactory area
M - Memory
- hippocampus
E - Emotions
- amygdala
Which developed first, the limbic system or the neocortex?
The limbic system is phylogenetically older and was present before the brain developed
the neocortex evolved later in development and is responsible for higher order functions
What is the cingulum?
The cingulum is underlying the cingulate gyrus
it receives information from pre-frontal, parietal, occipital and temporal gyri
it is involved in the formation of memories and emotions
What kind of subcortical white matter fibre type is the cingulum?
Association fibres
these white matter fibres interconnect regions of one hemisphere with the limbic lobe and the hippocampus
What is the role of the limbic system?
The limbic system is concerned with the regulation of drive and affective behaviour and plays a crucial role in memory and learning
What parts of the limbic system are concerned with emotions and memory?
Amygdala - emotional brain:
- emotional and motivational aspects of behaviour
- e.g. pain, pleasure, rage
- provides emotional component to the learning process
Hippocampus - associated with memory
What is the amygdala?
Where is it found and what is its main function?
It is an almond shaped nuclear complex (collection of cell bodies) in the medial temporal lobe
it is located deep to the uncus
it is mainly involved in emotions and behaviour
What is the primitive role of the amygdala?
How can we control this?
The primitive role is important for species preservation
e.g. feeding, drinking, sex, nurturing, need for survival
we have control of the amygdala due to the neocortex allowing us to rationalise and acquire context, whereas animals do not
What is the hippocampal formation (hippocampus)?
Where is it found and what is its main role?
Nuclear complex (nerve cell bodies) in the medial temporal lobe
it is found deep to the parahippocampal gyrus
it is mainly involved in memory
What happens if there is a lesion in the hippocampal formation?
Lose the ability to form new memories
the hippocampal formation is mainly involved in formation of short term memories, so it is difficult for a single lesion to affect long term memories
Where is the cingulum?
What are the landmarks of the limbic system?
Landmarks are the bumpy regions we can see in the brain as they have something underneath them
the cingulum is a bundle of association fibres bringing information from the cortex and towards the limbic system
What are the connections associated with the limbic system?
Stria terminalis:
- connects the amygdala to the hypothalamus
Fornix:
- connects the hippocampus to the hypothalamus
- they both follow the curves of the lateral ventricles