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FNS 5: Limbic
Neuro Lecture 5: Limbic System + Emotion
Question | Answer |
---|---|
Where is the amygdala located? | deep to the uncus (a surface feature on the rostral part of the paraventricular gyrus) |
What are the 2 major macrostructures of the amygdala? | 1) Basal-lateral nuclear complex and 2) Centromedial complex |
Which of the 2 major macrostructures of the amygdala is the primary input center? | Basal-lateral nuclear complex |
How many nuclei does the Basal-lateral nuclear complex include? | several |
Where does the Basal-lateral nuclear complex receive sensory input from? | thalamus, cortex, and limbic cortical regions (PFC, orbitofrontal) |
How many nuclei does the Centromedial complex include? Name them. | 2- central and medial nuclei |
Which of the 2 major macrostructures of the amygdala is the primary output center? | Centromedial complex |
Where does the Centromedial complex have connections to? | HT and several brainstem regions of autonomic function |
Where does the Central group receive input from? Project to? | input from basal-lateral group, projects to HT and brainstem ‘effector’ areas |
Where do Medial group interconnections go to? | Olfactory areas (bulb, cortex) |
Where does the Basal-lateral Group receive extensive input from? | limbic and sensory cortical areas |
Name the 2 major fiber bundles that connect the amygdala with subcortical regions. | 1) Stria terminalis, and 2) Ventral Amygdalofugal Pathway |
What is the other name for the Ventral Amygdalofugal Pathway? | Ventral Amygdaloid Pathway |
Where does the Stria terminalis exit the amygdala? | the posterior portion |
Where does the Stria terminalis course/run? | takes a C-shaped course along the medial aspect of caudate nucleus, and courses downward at the level of the anterior commissure to enter the hypothalamus |
Where does the Ventral Amygdalofugal Pathway exit the amygdala? | the dorsomedial part |
Where does the Ventral Amygdalofugal Pathway run/course? | runs beneath the globus pallidus and into the hypothalamus |
Which amygdala connection provides information about the external environment, including possible threats? | olfactory system, limbic association cortex, prefrontal cortex |
Which amygdala connection allows the amygdala to influence visceral, autonomic, and behavioral output? | hypothalamus, brainstem, dorsal/ventral striatum |
Which amygdala connection allows for memory formation? | Hippocampal formation and parahippocampal gyrus |
Which amygdala connection also allows for memory formation and allows an indirect influence over the prefrontal cortex? | Mediodorsal nucleus of the thalamus |
Which amygdala connections allow for neuromodulatory control? | basal forebrain (ACh), brainstem regions like ventral tegmental area (DA), locus coeruleus (NE), and raphe nuclei (5-HT) |
What is the main function of the amygdala? | recognition of the emotional salience of stimuli- impart emotional content to memory formation |
When a stimulus is emotionally-salient, what general systems can be affected by the amygdala? | endocrine, autonomic, and behavioral responses |
Under which type of stimuli are amygdala functions most evident? | fearful situations |
Which type of drugs act on the amygdala to inhibit fear responses? | Anxiolytic drugs, like benzodiazepines |
Does classical fear conditioning require protein synthesis? | Yes |
What, besides the classical fear conditioning model, is another form of learning that requires protein synthesis? | Extinction |
What happens when a weak neutral stimulus is paired with a strong primary reinforcer? | the weak input is strengthened in a Hebbian-like manner- it may acquire the ability to activate amygdalar pathways that evoke emotional/physiological responses |
What do NMDA glutamate antagonists do? | block the Hebbian-like association of a neutral stimulus with a strong primary reinforcer (Pavlov fear, etc.), AND prevent LTP |
What is the anatomical description of Urbach-Wiethe disease? | bilateral calcification and atrophy of anterior-medial temporal lobe structures (including amygdala), while sparing the hippocampus |
What were the symptoms of patient S.M.? | impaired recognition of fear faces, impaired conditioned autonomic/visceral responses to fearful stimuli, but preserved declarative recall of CS/US pairings |
What are CS? US? | Controlled stimulus (neutral) and Uncontrolled stimulus (primary reinforcer) |
What is the example of acquired forms of amygdalar damage? | Kluver-Bucy syndrome |
How was Kluver-Busy syndrome first produced/seen? | in monkeys by lesioning the medial temporal lobe (including the amygdala) in 1939 |
What are 3 symptoms of Kluver-Busy syndrome? | Loss of fear/aggression, Hyperorality, and Inappropriate sexual behaviors- in humans, all symptoms are rare-most common presentation is emotional (fear) recognition deficits |
Where does ACh come from? | basal forebrain |
Where does DA come from? | ventral midbrain (ventral tegmental area) |
Where does 5-HT come from? | raphe nuclei |
Where does NE come from? | locus ceruleus |
Are neuromodulatory pathways distinct or diffuse? | diffuse- project to many limbic regions, often by poorly-defined pathways |
Do neuromodulatory transmitter systems “drive” limbic circuitry or just modulate it? | modulate interactions |
Where do cholinergic neurons in the basal forebrain project to? | hippocampus, amygdala, and neocortex |
What (in general) is ACh important for? | cognitive function (attention, learning, memory) |
Which types of neurons are lost in AD earliest/most consistently? | cholinergic |
Which types of neurons are the targets of some cognitive enhancers used to treat AD? What’s an example of such a drug? | cholinergic- donezepil; 4/5 FDA-approved drugs for AD are ACh-esterase inhibitors |
Where do DA neurons in ventral midbrain project to? | limbic and cortical regions |
VTA | |
What (in general) is DA important for? | motivated behavior and reward |
Which NT is implicated in reinforcing and addictive properties of psychostimulant drugs? | DA |
Which NT is implicated in certain neuropsychiatric disorders, like schizophrenia? | DA |
What is blocked by amphetamine, meth, and cocaine? | DA reuptake |
What is blocked by antipsychotic drugs? | DA receptors |
Where do 5-HT neurons in the raphe nuclei project to? | almost all limbic and cortical regions |
What (in general) is 5-HT involved in? | modulating mood and affect |
Which types of disorders is 5-HT involved in? | depression, anxiety, and OCD |
Which types of drugs are used to treat 5-HT disorders? | SSRIs |
Where do NE neurons from the locus coeruleus and lateral tegmentum project to? | widespread projections to cortical and limbic regions |
What (in general) is NE involved in? | arousal, wakefulness, attention |
Drugs target activation of psychostimulant drugs (amphetamine, cocaine), but not rewarding properties by affecting which NT? | NE |
What type of disorders is NE involved with? | mood disorders |
Older antidepressants elevate ___ levels by blocking reuptake or preventing extracellular enzyme degradation. | NE |
What are the older antidepressants that block NE reuptake called? | tricyclics |
What are the older antidepressants that prevent NE extracellular enzyme degradation? | MAO inhibitors (monoamine oxidase) |