L08 Singh The Limbic System

Question 1

Name the three divisions of the amygdala

Answer 1

1. basolateral
2. corticomedial
3. central nucleus

Question 2

What is the function of the basolateral division of the amygdala?

Answer 2

EMOTIONAL SIGNIFICANCE. Connects to the cortical association areas (via the dorsal medial nucleus of thalamus); involved in attaching emotional significance to a stimulus. Lesion might result in a dead-pan affect (eg nothing affects them).

Question 3

What is the function of the corticomedial division of the amygdala?

Answer 3

ENDOCRINE. Connects to VMN of hypothalamus (via stria terminalis); involved in appetite behavior.

Question 4

What is the function of the central nucleus of the amygdala?

Answer 4

AUTONOMICS. Connects to brainstem and autonomic centers in hypothalamus; regulates visceral and cardiovascular function.

Question 5

What are the 4 main functions of the limbic system?

Answer 5

HOME: Homeostasis, olfaction, memory, emotion.

Question 6

Name the 4 main limbic association cortices

Answer 6

1. cingulate gyrus
2. parahippocampal gyrus
3. medial orbitofrontal gyri
4. gyri of the temporal pole

Question 7

Name the major structures of the limbic system.

Answer 7

1. limbic association cortex & cingulum
2. hippocampus & fornix
3. amygdala & stria terminalis.

Question 8

Name 3 areas of the limbic system that receive input from the olfactory system (ie the olfactory projection area).

Answer 8

1. priform cortex
2. entorhinal cortex
3. amygdala

Question 9

Outline the pathway associated with the conscious discrimination of odors

Answer 9

Piriform cortex –> thalamus –> frontal lobe

Question 10

The olfactory bulb/nerve send fibers to the olfactory cortex via the _____.

Answer 10

Lateral olfactory stria

Question 11

What cortical area is related to memories associated with odors?

Answer 11

Entorhinal cortex (which is associated with the hippocampus)

Question 12

What are the three effector systems of emotion?

Answer 12

1. Somatic (ie behavioral signs)
2. Endocrine (eg VMN of hypothalamus –> arcuate nucleus, activating the hypothalamic-pituitary-adrenal axis)
3. Autonomic (primarily sympathetic): central amygdaloid nucleus –> dorsal motor nucleus of vagus via amygdalofugal pathway. Also regulated by hypothalamus.

Question 13

Which corticolimbic structure is responsible for dilation of pupils, salivation, arousal etc?

Answer 13

Orbitofrontal cortex

Question 14

Which structure did Phineas Gage damage that impeded his ability to check inappropriate behaviors?

Answer 14

Ventromedial prefrontal cortex

Question 15

Which structure coordinates peripheral expression of emotional states?

Answer 15

Hypothalamus

Question 16

Outline the Papez circuit.

Answer 16

Question 17

What changes did Mclean make to the Papez circuit?

Answer 17

He added that the hippocampus communicates with the amygdala, which then also communicates with the mamillary bodies via the stria terminalis.

Question 18

What fibers carry connections from the amygdala to cortical association areas?

Answer 18

The uncinate fasciculus

Question 19

Which nucleus of the hypothalamus receives olfactory information that alters appetite?

Answer 19

Ventromedial nucleus (VMN) - fibers from corticomedial nucleus of amygdala

Question 20

Which nucleus of the hypothalamus influences endocrine responses to fearful and/or stressful responses?

Answer 20

Paraventricular nucleus (PVN)

Question 21

What general functions are the ventral amygdalofugal pathway from amygdala to forebrain involved with?

Answer 21

Cognition, motivation

Question 22

What general functions are the ventral amygdalofugal pathway from amygdala to hypothalamus involved with?

Answer 22

Homeostasis, behavioral arousal.

Question 23

What general functions are the ventral amygdalofugal pathway from amygdala to brainstem involved with?

Answer 23

Autonomics (connects periaqueductal grey, CN X nucleus, reticular formation, and parabrachial nucleus)

Question 24

The medial forebrain bundle is a large nerve bundle that connects ________, _________, and ________.

Answer 24

Amygdala, hypothalamus, and brainstem.

Question 25

Bilateral amygdalar lesions result in _________, which is characterized by ________.

Answer 25

Kluver-Bucy syndrome; “tameness”, psychic blindness (failure to place emotional context), loss of sexual inhibition.

Question 26

Electrical stimulation of the amygdala can lead to _______.

Answer 26

Feelings of fear; deja vu; olfactory hallucinations.

Question 27

Temporal lobe seizures that affect the limbic system can show the following symptoms:

Answer 27

“Dreamy state”; olfactory/auditory hallucinations; acute memory loss.

Question 28

Uncinate seizures lead to:

Answer 28

“Dreamy state”; feelings of deja vu.