Week 13: The Limbic System Flashcards
What are the functions of the limbic system?
control of memory and emotion and co-ordination of autonomic responses
Which structures make up the limbic system?
limbic lobe
amygdala
hippocampal formation
circuit of papez
How are the olfactory bulb and tract involved in the limbic lobe?
smell can trigger emotion and memory
What structures are found in the limbic lobe?
- cingulate sulcus
- cingulate gyrus
- isthmus
- parahippocampal gyrus
- uncus
what is the isthmus?
- narrowed region of the cingulate gyrus
- cingulate gyrus becomes continous with the parahippocampal gyrus at the isthmus
Which structure is deep to the uncus?
the amygdala
Which structure is deep to the parahippocampal gyrus?
hippocampus
Which structure is deep to the cingulate gyrus?
cingulum
What is the main function of the:
- Hypothalamus
- Paraolfactory area
- Hippocampus
- Amygdala
(HOME)
- Homeostasis
- Olfaction
- Memory
- Emotions
HOME
What is the function of the cingulum?
- nerve tract of association fibres that receives information from pre-frontal, parietal, occipital and temporal gyri
- involved in the formation of memories and emotion
Where is the amygdala?
- almond shaped nuclear (cell bodies) complex in the medial temporal lobe
- deep to the uncus
What is the amygdala involved in?
- emotions and behaviour
- pain, pleasure, rage
Where is the hippocampal formation?
- medial temporal bone
- deep to the parahippocampal gyrus
What is the hippocampal formation involved in?
-memory (mainly short term)
Why is a lesion to the brain more likely to affect short term memory than long term memory?
long term memory is more wide spread and involves other areas of the neocortex so one lesion is less likely to affect long term memory
How is the amygdala connected to the hypothalamus?
via stria terminalis
How is the hippocampus connected to the hypothalamus?
via the fornix
Why can emotion trigger autonomic response e.g heart race increasing during stress
because the stria terminalis and fornix connect the amygdala and hippocampus respectively to the hypothalamus which is involved in homeostasis
The fornix and stria terminalis follow the curves of which structure?
lateral ventricles
Explain the 4 connections/links the amygdala has
- Unprocessed visual, auditory, somatosensory, gustatory and olfactory stimuli
- Cortex: cingulate and parahippocampal gyri - processed visual, auditory, somatosensory, gustatory and olfactory stimuli
- Nuclei of ANS: brainstem and hypothalamus
- Stria terminalis
What are the two parts of the hippocampal formation?
- dentate gyrus
- hippocampus proper
How do efferent fibres from the hippocampus reach the hypothalamus
- via the fornix
- fimbria of the fornix start to collect and leave the hippocampus formation
- the fornix becomes continous with the crus, body, columns of the fornix then the mamillary bodies to reach the hypothalamus
What is the function of the hippocampal commissure?
allows for communication between the fornix on either side
Where are mammillary bodies found?
- posterior to optic chiasma and infundibulum
- part of the hypothalamus
What is the function of the circuit of papez?
reinforcement of emotion, memory, and olfaction with each other for survival responses
What type of circuit is the circuit of papez
closed, bidirectional
Explain the circuit of papez
hippocampus –> fornix –> mammillary bodies (ANS responses) –> anterior thalamic nuclei –> cingulate gyrus –> hippocampus
cingulate fibres can be sent back to the hippocampus so we can memorise feelings and emotions
The hippocampus receives all types of information via what structure?
the cingulum
What happens when we try to learn specific items of important information?
- these items are rehearsed repeatedly until they are permanently stored in the areas of the cortex associated with long term memory
- long term memory is less localised
How does the hypothalamus have a role in endocrine function
- inputs to hypothalamus, modulatory role
- hypothalamus connected to pituitary
What is the definition of memory?
the mental capacity to encode, consolidate, store and retrieve information
What are the 4 different types of memory?
- Sensory memory
- what we see/ hear/ touch (visual/auditory/haptic)
- quick and short lived - Working memory
- stored in hippocampus
- information we temporarily hold onto whilst we learn - Recent memory
- stored in hippocampus - Remote memory
- long term memory
- stored in neocortex
- maximum capacity
How can we get information from our sensory memory into our remote memory?
sensory memory is sent to our working memory which encodes information to our recent memory, and if consolidated enough, will become part of our remote memory
What is consolidation?
when we take new memories from the hippocampus and bring them to the neocortex for permanent storage
