Structure and Function - Week 2 Limbic system Flashcards
What is the limbic system and what is its function? (3)
Functional group of structures (inc. hippocampus & amygdala)
Outputs to the basal ganglia, autonomic nervous system, and the endocrine system
Involved in behaviour, motivation, memory, learning, emotion (mental states), movement etc
What is the key function of the hippocampus? (1)
Memory consolidation, learning, spatial navigation
What is the key function of the amygdala? (1)
Emotion, fear, reward (all have links to memory too)
Describe the gross anatomy of the hippocampus (3)
Hippocampus = “seahorse”.
Another early term was “cornu Ammonis” – horn of Amun. Name still exists in cellular structure
Curved structure found as an inward fold of the cerebral cortex in the medial temporal lobe
Describe the basic circuit of the hippocampus (2)
Information flows from the superficial layers of the entorhinal cortex (EC) to the hippocampus (HC)
Output from CA1 or sub return to deep layers of EC (e.g. layer V).
Describe the perforant path (3)
Input into hippocampus
ECII –> DG, CA3
ECIII –> CA1, Sub
Describe the dentate gyrus (3)
Granule Cell Layer – glutamatergic neurons projecting to CA3
Subgranular zone – site of adult neurogenesis (the generation of new neurons)
Hilus also contains glutamatergic mossy cells
Describe mossy fibres (3)
Axons from granule cells bundle together to form the Mossy fibers which synapse on to the dendrites of CA3 pyramidal cells
Axon leaves towards CA1 or forms collaterals (branches) – recurrent collaterals
Some axons return to the DG hilus
What is the Trisynaptic loop and draw a diagram ? (3)
Trisynaptic: EC-DG, DG-CA3, CA3-CA1.
Widely studied circuit that highlights mostly unidirectional flow.
Check notes - week 2 structure and function
What is CA2? (2)
CA2 receives input from the EC, DG, and CA3
It outputs to CA1
What is CA4? (1)
A (disputed) term for the hilus of the dentate gyrus
How can glutamatergic pyramidal cell activity be modulated? (1)
Glutamatergic pyramidal cell activity can be modulated by a huge diversity of GABAergic (inhibitory) interneurons
Describe the gross anatomy of the amygdala (3)
Anterior to hippocampus.
3 subcortical nuclei make up the amygdala: central, corticomedial, and basolateral
various subdivisions of the above + additional nuclei may be included.
What is the function of the amygdala? (4)
Various functions (dependent on inputs and outputs) including regulation of visceral response to stimuli, attaching emotional significance to stimuli, and emotional affective responses
Describe the cellular structure of the amygdala (2)
GAD67-EGFP mice reveal GABAergic interneurons in individual nuclei of the amygdala
Note highest expression in the CeL (central lateral amygdala)
