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
what is the differences between corticomedial and ventrolateral divisions of the amygdaloid body?
ventrolateral does not receive direct input from olfactory bulb
ventrolateral is main output area
What are the inputs/outputs to the basolateral nuclei of the amygdaloid body?
- input from thalamus, reticular formation
- reciprocal to frontal/temporal/cingulate gyri
What are the inputs/outputs to the basolateral nuclei of the amygdaloid body?
- input from thalamus, reticular formation
- reciprocal to frontal/temporal/cingulate gyri
What are the inputs/outputs to the central nucleus of the amygdaloid body?
- most input from basolateral amygdala & corticomedial group
- reciprocal to prefrontal/temporal/cingulate gyri
outputs to - septal area, preoptic area, hypothalamus
- vagus nerve
- nucleus accumbens & dorsomedial thalamus
What is the pathway of information through the limbic system?
- associative cortex
- cingulate cortex
- hippocampus
- hypothalamus
- anterior thalamus
- cingulate cortex
- associative cortex
