Limbic System Flashcards
(23 cards)
Describe the papez circuit
Cingulate gyrus -> hippocampus -> mammillary bodies (hypothalamus) -> anterior nuclei of thalamus -> cingulate gyrus
Describe the amygdala and it’s subdivisions
Collection of nuclei beneath uncus. Nuclei subdivided into medial, central, and basolateral (biggest).
Describe the connections of the medial nuclei
Interconnected with olfactory system. Feeds it to hypothalamus.
Describe the connections of the central nuclei
Important in emotional responses. Connected with hypothalamus and brainstem.
Describe the connections of the basolateral nuclei
Largest part of human amygdala. Emotion center, connected with cortex.
What are the amygdala inputs?
Olfactory bulb - medial nuclei
Brainstem visceral nuclei - central nuclei
Unimodal sensory cortex, anterior limbic cortex, thalamus (sensory relay nuclei), and hypothalamus - basolateral nuclei.
What are the amygdala outputs?
Unimodal sensory cortex, anterior limb cortex, ventral striatum, thalamus (dorsomedial nucleus), hypothalamus, brainstem visceral nuclei, and hippocampus.
How do fibers leave the amygdala?
Via Stria Terminalis and ventral amygdalofugal pathway.
Describe Kluver-Bucy syndrome.
Bilateral lesion to anterior tips of temporal lobes. Results in: Docility, Hyperphagia (eat anything), Hyperorality (examine objects by mouth), Hypersexuality (seek sexual stimulation from unusual or inappropriate objects), and visual agnosia (inability to recognize familiar objects or people).
What is the function of the hippocampus?
Functions as an index - keeping track of where all the pieces of a memory are stored. Involved in anterograde memory.
Describe the layered structure of the hippocampus.
In temporal lobes. Three layered structure: dentate gyrus, hippocampus proper, and subiculum.
What connects the hippocampus to mammillary bodies?
Fornix
What connects the hippocampus to the association cortex?
Parahippocampal gyrus
Describe the effects of bilateral damage to the hippocampus
Anterograde amnesia. New memories or facts cannot be formed.
What are the hippocampal inputs.
Unimodal, multimodal, and limbic cortical areas. Septal nuclei (modulatory cholinergic inputs via the fornix). Amygdala.
What are the hippocampal outputs.
Unimodal, multimodal, and limbic cortical areas. Indirect outputs to limbic cortex via mammillary bodies through fornix. Fornix is predominant output of hippocampus.
Discuss hippocampal damage in Alzheimer’s disease.
Hippocampal damage: anterograde amnesia of declarative (not non-declarative) memories.
Describe Wernicke-Korsakoff syndrome
Due to vitamin B1 deficiency. Causes anterograde and retrograde memory impairment.
What is the function of the mammillary nuclei of the hypothalamus?
Critical for spatial memory/position of head in space. Massive input from hippocampus via fornix.
What are the functions of septal nuclei?
Regulates reproductive and sexual behaviors, and facilitates memory formation.
What are the afferents for septal nuclei?
Hippocampus, amygdala, and preoptic area of hypothalamus.
What are the efferents for septal nuclei?
Hippocampus, amygdala, preoptic area, mammillary body, and median eminence.
What is the effect of lesions to septal nuclei?
Stroke can knock out both septal nuclei. Lesions -> septal syndrome: behavioral overreaction, septal rage.
