The Limbic System

Question 1

limbic cortex

Answer 1

cingulate gyrus and parahippocampal gyrus

Question 2

hippocampal formation

Answer 2

dentate gyrus- 3 layers- acellular, graunlar, and inner polymorphic

hippocampus- 3 layers- molecular, pyramidal, and inner polymorphic

contains 4 different cell regions- CA1, 2, 3, and 4

subiculum- composed of presubiculum, parasubiculum, and subiculum

transition zone between 6 layered entorhinal cortex and 3 layered hippocampus

Question 3

amygdala anatomy

Answer 3

located beneath the uncus

contains 13 nuclei, of note:

basolateral 
basomedial
lateral amygdalar
centromedial, lateral, and central
extended amygdala
septal nuclei

Question 4

cingulum

Answer 4

cingulate to amygdala tract/parahippocampal gyrus

Question 5

fornix

Answer 5

output from hippocampus (entorihnal and subiculum) to hypothalamus

3 divisions: precommissural, postcommissural, and nonfornical

Question 6

mammillothalamic tract

Answer 6

mammillary bodies to anterior and dorsal thalamus

Question 7

anterior thalamic projections

Answer 7

input from fornix and mammillothalamic tracts

output to orbitofrontal cortex and cingulate

Question 8

unicate fasciculus

Answer 8

originate in anterior temporal lobe, uncus, amygdala

enters orbitofrontal cortex

Question 9

stria terminalis

Answer 9

output from amygdala terminateing in septum/hypothalamus

Question 10

stria habelularis

Answer 10

septal nuclei to habenula

Question 11

ventra amygdalofugal pathway

Answer 11

output from amygdala to hypothalamus

Question 12

basolateral amygdalar circuit

Answer 12

set of connections that encodes and relays information pertinent to social signals and social acts

ex empathy or inference

Question 13

spatial orientation

Answer 13

hippocampus-diencephalon tracts (fornix and mammillothalamic tracts) and the parahippocampal-retrosplenial cortex (cingulum) contains information with spatial info and memory

Question 14

integration of emotional and visceral states

Answer 14

temporo-amygdala-orbitofrontal cortex via unicate fasciculus- activated during introspective thought

deactivated during goal directed tasks

damage results in mood disorders

Question 15

insula

Answer 15

connections to insula are important for interepreting visceral autonomic responses and imposing them on salience

interoception- sense of the physiological condition of the body

Question 16

kluver bucy syndrome

Answer 16

loss of normal fear and anger responses, hypersexuality, hyperphalagia, visual agnosia

Question 17

difference between fear and anxiety

Answer 17

central nucleus of amygdala- acquisition and expression of fear to events

bed nucleus of stria terminalis- sustained, diffuse anxiety

connected via extended amygdala

Question 18

fear conditioning

Answer 18

lateral amygdala is most important structure for conditioned fear

after training, the conditioned stimulus is sufficient to produce activity out of lateral amygadala activating fear pathways, indicating that a change in the firing pattern of the LA is associated with a learned fear response

Question 19

importance of environment to fear response

Answer 19

lateral amygdala can adapt in response to training to conditioned stimulus, but the environment in which the training occured is also sufficient to elicit a fear response

Question 20

extinction and reconsolidation

Answer 20

reconsolidation- allows information associated w/ the memory to be updated and reinforced. occurs everytime a memory is retrieved

extinguishing- not a degradation, substition of a new memory where an aversive pairing no longer exists

Question 21

key processes of extinction

Answer 21

NMDA receptors in basolateral amygdala are required for acquisition of fear extinction

fear extinction associated with change in synaptic strength of projections from hippocampus to mPFC

Question 22

PTSD

Answer 22

characterized by the inappropriate retrieval of fear memories leading to maladaptive arousal and stress

drugs interfering w/ reconsolidation or augementing extinction have some success w/ PTSD

Question 23

optogenetics and dentate gyrus

Answer 23

encode contextual memory engrams- project to basolateral amygdala

stimulation via optogenetics created a false contextual fear memory

valence (fear or reward) could also be manipulated

Question 24

theories of cognitive decision making

Answer 24

balance between emotional and congnitive processes

striatum, amygdala, mPFC, OFC, insular cortex

vs

dlPFC, aPFC, posterior parietal cortex

Question 25

stress in goal directed behaviors

Answer 25

stress dependent changes in dlPFC correlate w/ decrease in goal directed behavior and increase in habitual behavior signaling via norepi and glucocorticoids contribute to habitual behavior stress impairs PFC functioning in decision making and increases risky decision making

Question 26

insula is involved in social decision making

Answer 26

ok

Question 27

integration of mood into decision making

Answer 27

insula and ventral striatum involved, w/ interpretation that involvement of VS signified reduced reward associated w/ decision making hypothesis- activity in regions that regulate emotion and its reward (amygdala, ventral striatum) shift neural processing circuits that underlie subjective value assessments (OFC)

Question 28

vmPFC

Answer 28

damage shows lover impact of social factors in decision making

Question 29

implicit bias structures

Answer 29

amygdala, insula, cingulate, OFC fast, automatic, no processing

Question 30

explici bias structures

Answer 30

PFC, frontopolar cortex slow, conscious, cognitively taxing

Question 31

reapprasial

Answer 31

conscious override of unconscious assessments

Question 32

stereotyping

Answer 32

priming of stereotyping done by vmPFC output to dlPFC dlPFC then has task of overriding or suppressing those stereotypes

Question 33

extended amygdala

Answer 33

part of anxiety circuit

Question 34

CRF

Answer 34

elevated CRF is hallmark of anxiety differential expression in extended amygdala may explain sex specific differences to stress CRF increases 5-HT receptor internalization, increasing anxiety like behavior (more so in women than men) 5-HT receptors are also internalized by CRF drugs promoting 5HT are major target for therapy

Question 35

BnST and stress

Answer 35

central amygdala projects to basal nucleus of stria terminalis w/ CRF- connection for anxiogenic action