Limbic System

Question 1

Describe the papez circuit

Answer 1

Cingulate gyrus -> hippocampus -> mammillary bodies (hypothalamus) -> anterior nuclei of thalamus -> cingulate gyrus

Question 2

Describe the amygdala and it’s subdivisions

Answer 2

Collection of nuclei beneath uncus. Nuclei subdivided into medial, central, and basolateral (biggest).

Question 3

Describe the connections of the medial nuclei

Answer 3

Interconnected with olfactory system. Feeds it to hypothalamus.

Question 4

Describe the connections of the central nuclei

Answer 4

Important in emotional responses. Connected with hypothalamus and brainstem.

Question 5

Describe the connections of the basolateral nuclei

Answer 5

Largest part of human amygdala. Emotion center, connected with cortex.

Question 6

What are the amygdala inputs?

Answer 6

Olfactory bulb - medial nuclei
Brainstem visceral nuclei - central nuclei
Unimodal sensory cortex, anterior limbic cortex, thalamus (sensory relay nuclei), and hypothalamus - basolateral nuclei.

Question 7

What are the amygdala outputs?

Answer 7

Unimodal sensory cortex, anterior limb cortex, ventral striatum, thalamus (dorsomedial nucleus), hypothalamus, brainstem visceral nuclei, and hippocampus.

Question 8

How do fibers leave the amygdala?

Answer 8

Via Stria Terminalis and ventral amygdalofugal pathway.

Question 9

Describe Kluver-Bucy syndrome.

Answer 9

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).

Question 10

What is the function of the hippocampus?

Answer 10

Functions as an index - keeping track of where all the pieces of a memory are stored. Involved in anterograde memory.

Question 11

Describe the layered structure of the hippocampus.

Answer 11

In temporal lobes. Three layered structure: dentate gyrus, hippocampus proper, and subiculum.

Question 12

What connects the hippocampus to mammillary bodies?

Answer 12

Fornix

Question 13

What connects the hippocampus to the association cortex?

Answer 13

Parahippocampal gyrus

Question 14

Describe the effects of bilateral damage to the hippocampus

Answer 14

Anterograde amnesia. New memories or facts cannot be formed.

Question 15

What are the hippocampal inputs.

Answer 15

Unimodal, multimodal, and limbic cortical areas. Septal nuclei (modulatory cholinergic inputs via the fornix). Amygdala.

Question 16

What are the hippocampal outputs.

Answer 16

Unimodal, multimodal, and limbic cortical areas. Indirect outputs to limbic cortex via mammillary bodies through fornix. Fornix is predominant output of hippocampus.

Question 17

Discuss hippocampal damage in Alzheimer’s disease.

Answer 17

Hippocampal damage: anterograde amnesia of declarative (not non-declarative) memories.

Question 18

Describe Wernicke-Korsakoff syndrome

Answer 18

Due to vitamin B1 deficiency. Causes anterograde and retrograde memory impairment.

Question 19

What is the function of the mammillary nuclei of the hypothalamus?

Answer 19

Critical for spatial memory/position of head in space. Massive input from hippocampus via fornix.

Question 20

What are the functions of septal nuclei?

Answer 20

Regulates reproductive and sexual behaviors, and facilitates memory formation.

Question 21

What are the afferents for septal nuclei?

Answer 21

Hippocampus, amygdala, and preoptic area of hypothalamus.

Question 22

What are the efferents for septal nuclei?

Answer 22

Hippocampus, amygdala, preoptic area, mammillary body, and median eminence.

Question 23

What is the effect of lesions to septal nuclei?

Answer 23

Stroke can knock out both septal nuclei. Lesions -> septal syndrome: behavioral overreaction, septal rage.