Limbic System

Question 1

Major function of limbic system:

Answer 1

The site where cortical information and hypothalamic impulses are integrated.

Homeostasis, olfaction, memory, emotion (HOME)

Question 2

Components of Papez’ circuit:

Answer 2

Anterior thalamus
Cingulate
Hippocampus
Fornix
Mammillary bodies

Question 3

What is the Default Mode Network?

Answer 3

Dorsal portion of the Papez circuit interconnected through the dorsal cingulum. Activated when the mind is at rest (zoning out, day-dreaming, etc).

Question 4

Cingulate cortex functions:

Answer 4

Rostral: emotions and motor.
Caudal: visual spatial and memory.

Question 5

Orbital frontal lobe functions:

Answer 5

Personality, behavioral control, self-awareness.

Question 6

Temporal lobe functions:

Answer 6

Visual memory, language comprehension.

Question 7

Amygdala functions:

Answer 7

“Preservation of self”, emotion, fear

Question 8

Septum function:

Answer 8

“Preservation of species”, sexual behavior, emotionality.

Question 9

Connects the hippocampus and mammillary bodies:

Answer 9

Fornix

Question 10

Connects the mammillary bodies and thalamus:

Answer 10

Mammillothalamic tract

Question 11

Connects the entorhinal cortex and dentate:

Answer 11

Perforant path

Question 12

Updated Papez’ circuit includes:

Answer 12

Prefrontal cortex, hypothalamus, amygdala.

Question 13

Function of mammillothalamic tract:

Answer 13

Connect visceral perception with emotion and behavior.

Question 14

Function of perforant path:

Answer 14

Major afferent to the hippocampal formation

Question 15

Function of fornix:

Answer 15

Major efferent from the hippocampal formation

Question 16

Common physiologic and neurochemical properties

Answer 16

1. Herpes virus has a special affinity for limbic system (leads to severe memory and behavioral disturbance).
2. Susceptible to kindling and development of seizure foci.
3. High density of cholinergic innervation and opiate receptors.

Question 17

Description of updated limbic system model:

Answer 17

3 distinct but partially overlapping networks

Question 18

Describe Kluver-Bucy syndrome:

Answer 18

Cause: bilateral large temporal lobe lesions including amygdala, hippocampus, uncus.

Symptoms: Oral tendencies, hypermetamorphosis, placidity, hypersexuality, visual agnosia, bulimia.

Question 19

Describe Geschwind syndrome:

Answer 19

Cause: Sensory limbic hyperconnection-strengthening of synaptic connections.

Symptoms: Increased concern with philosophical, cosmic, religious issues; hyposexuality; hypergraphia; viscosity.

Question 20

Function of amygdala:

Answer 20

Integration of emotions, fear, memory.

Lesions lead to tameness or reduced emotionality.

Question 21

Orbital frontal lobe syndrome:

Answer 21

Disinhibited, tactless, grandiose, tendency to dress carelessly and eat gluttonously.

Question 22

Frontal/convexity or dorsolateral lobe syndrome:

Answer 22

Apathetic, responding in an automation-like manner, vacancy of expression.

Question 23

Medial frontal lobe syndrome:

Answer 23

“Motionless, mindless, wakefulness”, loss of drive to move or speak.

Question 24

Lesions in hippocampus, dorsal medial nucleus of the thalamus, mammillary nuclei lead to:

Answer 24

Amnesia and memory disorders (declarative memory)

Question 25

Episodic vs semantic memory:

Answer 25

Episodic memories are actively remembered. Semantic memories are facts known rather than actively remembered.

Question 26

Describe Wernicke Korsakoff’s Syndrome:

Answer 26

Cause: Chronic alcoholism and nutritional deficiency (thiamine). Lesion in mammillary bodies and thalamus.

Symptoms: Confusion, disorientation, oculomotor dysfunction, ataxia, chronic anterograde and temporally-graded retrograde amnesia.

Question 27

Damage to septal region produces:

Answer 27

Increased sexual activity and emotionality.

Question 28

Brain pleasure regions:

Answer 28

1. Lateral hypothalamus
2. Medial forebrain bundle
3. Nucleus accumbens

Question 29

Lesions to the ventromedial nucleus of hypothalamus produces:

Answer 29

Pain, rage, or strong aversive reactions and long-lasting hyperemotionality.

Question 30

Contralateral motor neglect results from a lesion where?

Answer 30

Posterior cingulate gyrus.

Question 31

Behavioral changes after lesions of the anterior cingulate gyrus:

Answer 31

Apathy, disinhibition, placidity, depression, anxiety, OCD, heightened sexuality, bulimia.

Lesions of AC can relieve obsessive compulsive behaviors and reduce Tourette syndrome symptoms.

Question 32

Function of anterior cingulate gyrus:

Answer 32

Integration of emotion with movement.