Limbic System Flashcards
What are the major anatomical regions that comprise the limbic system?
- Limbic lobe
- hippocampus
- dentate gyrus
- amygdaloid body
- hypothalamus
- anterior thalamus
what are the major regions of the hippocampus
- dentate gyrus
- Cornu Ammonis(CA1,CA2,CA3)
(both archicortex with principle cells) - subiculum (paleocortex transition zone)
- parahippocampal gyrus (neocortex)
What are the major cel types in the hippocampus
principle cells are
* pyramidal cells (in CA)
* granule cells (in DG)
What are the major inputs to the hippocampus?
- Cerebral cortex (associative areas)
- Septal area
- contralateral hippocampus
- reticular formation
What are major outputs from the hippocampus?
- reciprocal cortical connections
- diencephalon/brainstem via fimbria-fornix
What are the 3 layers of hippocampal cortex & describe them?
- Pyramidal cell layer
* large excitatory pyramidal cells
* dendrites extend into molecular layer
* axons leave the hippocampus
* synapse with other pyramidal cells - Molecular layer
* synaptic layer of dendrites/axons
* in the centre surrounding hippocampal sulcus - Polymorphic layer
* similar to Layer 6 neocortex
* axons, dendrites & inhibitory interneurons
What are the 3 layers of dentate gyrus & describe them?
- Granule cell layer
* granule cells - small DG principle cells - mossy fibres
* efferent from DG, synapse with CA2 & CA3 principle cells
* many branches - Hilus
* granule cell axons & inhibitory interneurons
Describe intrahippocampal circuitry
- associative cortex input
- parahippocampal gyrus
- subiculum
skips ahead via perforant pathway - DG granule cells
mossy fibres - CA2/CA3 principle cells
colateral efferent to fimbria-fornix
also schaffer colateral to - CA1 principle cells
colateral efferent to fimbria-fornix
otherwise continues to - back to subiculum
- parahippocampal gyrus
via alvear path back to - CA2/CA3 principle cells
What is fimbria-fornix?
- pathway from hippocampus through fimbria to fornix
- fornix curves around thalamus
- separates into columns above 3rd ventricle
- columns innervate septum, hypothalamus & mammilary bodies
Define the circuit of Papez
A ring of interconnected nuclei involved in emotion and emotional expression
Describe the circuit of papex circuitry
- parahippocampal gyrus
via perforant & alvear paths - hippocampal formation
fimbria-fornix - mamillary bodies
mammilothalamic fasciculus - anterior thalamic nuclei
internal capsule - cingulate gyrus
cingulum - parahippocampal gyrus
What are the inputs to the circuit of papez?
- neocortex
- thalamus
- septal area
- reticular formation
What are outputs from circuit of papez?
- neocortex
- reticular formation
- brainstem/spinal cord
What are the major divisions of the amygdaloid body?
Corticomedial group
ventrolateral division
* basolateral
* central
What are the inputs to the corticomedial group of the amygdaloid body?
input direct from olfactory bulb
