Limbic System

Question 1

What structures comprise the cortical limbic system? (5)

Answer 1

• Hippocampus
• Parahippocampal gyrus
• Cingulate gyrus
• Orbital frontal cortex
• Insular cortex

Question 2

What structures comprise the subcortical limbic system? (5)

Answer 2

• Amygdala
• Some thalamic nuclei
• Septal nuclei
• Hypothalamus
• Ventral tegmental area

Question 3

What are the functions of the limbic system? (4)

Answer 3

HOME (homeostasis, olfaction, memory, emotions/drive)

Question 4

What is emotion? Basic Pathway?

Answer 4

• Set of physiological responses when brain detects pos or neg significant stimulus (largely unconscious) –> cognitive (attention, memory, decision) endocrine, autonomic and musculoskeletal changes in body
  
  • Vs. feeling (conscious)
• Emotional stimuli –> sensory systems –> emotion systems –> hypothalamus and brainstem –> somatic motor nerves + autonomic nerves + pituitary (AKA bodily changes are mediated by endocrine, autonomic and somatic systems)

Question 5

Neural Circuit of Fear Conditioning

Answer 5

• Ex) noxious shock + tone
• Shock and tone info go to relative areas of thalamus –> auditory cortex/somatosensory cortex (which then also goes to amygdala) AND right to amygdala –> specifically comes into lateral nucleus of amygdala –> central nucleus of amygdala –> …

central gray (somatic motor)
 \+ lateral hypothalamus(autonomics) 
\+ paraventricular nucleus of hypothalamus (pituitary)

Question 6

Urbache - Wiethe Disease

Answer 6

• General thickening of skin and mucous membranes –> hardening of medial temporal lobes and amygdalas bilaterally
• Effects = impaired rational decision making; impaired ability to recognize and experience fear
• Perception, memory and language normal

Question 7

What does the amygdala do?

Answer 7

-Amygdala triggers brain arousal and body arousal in presence of threats via neuromodulators (NE, dopamine, serotonin, Ach)

• Amygdala connects cortex (pre-frontal areas for planning and organizing behaviors) and subcortical areas (hypothalamus & brainstem) via Triangular Circuit
• *B/n orbital and medial prefrontal cortex -> amygdala –> ventral BG –> mediodorsal nucleus of thalamus