Limbic System

Question 1

What are the cortical structures of the limbic system?

Answer 1

Parahippocampal gyrus

Cingulate gyrus

Insular cortex

Orbitofrontal cortex

Prefrontal association cortex

Question 2

What are the subcortical structures of the limbic system?

Answer 2

Amygdala

Ventral striatal structure

Thalamic nuclei - anterior and mediodorsal

Hypothalamus - anterior, posterior, mamillary nuclei

Ventral tegmental area

Question 3

What is the role of the insular cortex?

Answer 3

Empathy and theory of mind

Question 4

What is the role of the orbitofrontal association cortex?

Answer 4

Neocrotical area invovled in the integration of personality and emotional behavior

Question 5

What is the role of the prefrontal association cortex?

Answer 5

Executive function, working memory, and default mode network

Question 6

What is the role of the cingulate gyrus?

Answer 6

Papez circuit

Emotional modulation of pain, cortical regulation of basic autonomic functions, and memory

Internal cognition

Question 7

What is the role of the parahippocampal gyrus?

Answer 7

Learning and memory processes

Question 8

What is the role of the entorhinal cortex (Area 28)?

Answer 8

Located in the anterior portion of the parahippicampal gyrus

Major relay for inputs and outputs between the association cortex and hippocampal formation

First cortical area to degenerate in AD

Question 9

What is the role of the dentate gyrus?

Answer 9

Undergoes neurogenesis throughout life

Memory

Question 10

What is the role of the intrinsic hippocampal circuit?

Answer 10

Association cortex –> Entorhinal cortex –>hippocampus proper (via alvear and perforant pathways)

From here projections sent to various areas of the hippocampus and dentate gyrus

Feedback loop is created

Question 11

What is the role of the fornix?

Answer 11

Major output, three targets:

Medial and lateral mammillary nuclei

Lateral septal nucleus

Anterior thalamic nucleus

Question 12

Describe the papez ciruit

Answer 12

Hippocampus to mamillary bodies via fornix –> anterior thalamic nucleus via the mammillothalamic tract –> Cingulate gyrus via internal capsule –> back to the entorhinal cortex and hippocampus via the association pathway

Question 13

What is the role of the septal nuclei?

Answer 13

Endogenous reqard circuits

Receives input from the hippocampus, amygdala, hypothalamus, and ventral tegmental area

Question 14

What is the role of the amygdala?

Answer 14

Interpret and recall emotional content and olfactory memories, visual inputs and response

Fight or flight response, modd, and emotion

Question 15

What input does the amygdala receive?

Answer 15

Highly processed sensory information

Autonomic input

Question 16

What occurs from a lesion to the amygdala area of the brain?

Answer 16

Dysregulation of emotion

Docility, outbursts, rage, aggression, hyperphagia

Question 17

What are the medial diencephalic structures of the limbic system?

Answer 17

Anterior and mediodorsal nuclei of the thalamus

Mammillary bodies

Important for memory

Question 18

What are the medial temporal lobe structures of the limbic system?

Answer 18

Entorhinal cortex and the hippocampal formation

Reciprocal connections with the multimodal association cortex and are important for memory

Question 19

What results from bilateral damage to either MDS or MTLS?

Answer 19

Loss of declarative or explicity memory

Implicit memory remains intact

Question 20

What is Kluver-Bucy syndrome?

Answer 20

Results from temporal lobe resection or viral encephalitis

Hypersexuality, hyperphagia, increased curiosity, los of fear, reduced anger, dementia-like symptoms

Question 21

What disorders can result from amygdala hyperactivation?

Answer 21

Anxiety, panic attacks, PTSD, OCD

Question 22

Occlusion of which arteries will result in memory loss?

Answer 22

PCA

Superior portion of the basilar artery - more memory loss because it gives rise to both PCAs which supply the MTLS and MDS

Question 23

How can seizures affect memory loss?

Answer 23

Seizure-induced memory loss can occur with complex partial and generalized tonic-clonic seizures

If severe enough to cause hippocampal sclerosis, then memory loss can persist

Question 24

What is transient global amnesia?

Answer 24

Sudden and temporary onset of both retrograde and anterograde amnesia

85% of patients only have one episode, associated with extreme stress

Question 25

How can Wernike-Korsakoff syndrome affect the limbic system?

Answer 25

Can result in the degnereation of the MDS nuclei and hippocampal degeneration

Results in amnesia, poor impulse control and confabulation