Limbic System Anatomy

Question 1

Limbic lobe

Answer 1

Consists of the cingulate gyrus, isthmus, parahippocampal gyrus, and subcallosal gyrus

Question 2

Prefrontal cortex components

Answer 2

Dorsolateral PFC
Ventrolateral PFC

Medial PFC
Orbitofrontal cortex
Anterior cingulate cortex

Question 3

Major functions of the PFC?

Answer 3

Attention, concentration, executive control

Question 4

The Cingulum

Answer 4

A fiber bundle that projects from the cingulate gyrus to the entorrhinal cortex in the temporal lobe, also projects to the amygdala . Receives input from the thalamus (which receives input from the spinothalamic tract about pain/temp). Reinforces behaviors that reduce pain.

Question 5

Where does the entorrhinal cortex project to?

Answer 5

The hippocampal formation

Question 6

Components of the hippocampal formation

Answer 6

Hippocampus and dentate gyrus.

Question 7

Main output structure from hippocampal formation

Answer 7

Subiculum

Question 8

Order of processing from entorhinal cortex through hippocampal formation

Answer 8

Entorhinal cortex ->dentate gyrus -> CA3

Question 9

Projections of CA3

Answer 9

1) Via precommissural fornix to septal nuclei, ventral striatum (Accumbens and olfactory tubercle).
2) Via shaffer collaterals to CA1, which projects to the subiculum

Question 10

Where does the subiculum project?

Answer 10

Via the postcommissural fornix to the mammillary bodies

Question 11

Bilateral hippocampi removal?

Answer 11

Anterograde amnesia

Question 12

Effect of AD on hippocampus?

Answer 12

Shrinks

Question 13

Frontotemporal dementia symptoms

Answer 13

Dramatic changes in personality, socially inappropriate behavior, impulsivity, emotional indifference, language deficits.

Question 14

Hippocampal place cells

Answer 14

Generate a map of the environment

Question 15

Where do the mamillary bodies project after receiving input from postcomissural fornix?

Answer 15

Back to the thalamus (anterior group), which projects back to the cingulate cortex.

Question 16

Function of the basal forebrain, septal nuclear complex, ventral striatum

Answer 16

Memory, cognition, reward.. These are cholinergic systems.

Question 17

Cholinergic projection from septal nuclei to the hippocampus?

Answer 17

Via the fornix, important for cognition.

Question 18

Amygdala structure

Answer 18

Has basal and lateral nuclei, then central and edial nuclei

Question 19

Function of the amygdala

Answer 19

Learning associated with fear, memories associated with fear. Important in memory/cognition. Also, major epileptic focus.

Question 20

Kluver Bucy Syndrome

Answer 20

Bilateral lesions of the amygdala produce placidity, loss of fear, hypersexuality, and hyperphagia.

Question 21

Two main output pathways from the amygdala

Answer 21

The Ventral Amygdalo-fugal pathway - projects to the basal forebrain, hypothalamus, ventral striatum, and thalamus
(regulates emotional tone)

Stria terminalis and its bed nucleus- Important for sex, control of eating, and anterior pituitary control.

Question 22

HPA axis and limbic control

Answer 22

Controls cortisol secretion from the adrenal cortex, Hippocampus: inhibition. Amygdala: Excitation.

Question 23

Olfactory cortex and its association with the limbic system

Answer 23

Very strong. No thalamic relay.

Question 24

Two main dopaminergic limbic pathways

Answer 24

Mesolimbic- from VTA to NAS via median forebrain bundle. Mediates reward

Mesocortical pathway- From VTA to DLPFC, VMPFC, ACC, Olfactory bulb. Mediates cognition, memory, and emotion.