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What does the lymbic system control?
- A. emotion
- 1. physiological: ANS & hormonal
- 2. Behaviors: fight/flight
- 3. Psychological state: cortical mediated
- Bidirectional bridges of sensory(neocortex) & visceral/somatic motor (hypothalamus, ANS)
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Which parts of the CNS control visceral/somatic aspects of emotional behavior?
hypothalamus & brainstem (midbrain, pons, medulla)
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What is sham rage?
- In a cat
- autonomic: increase in BP, HR, pupildilation, piloerection
- somatic: arching back, extensding claws, snarling
- mediated by hypothalamus & brainstem (midbrain, pons, medulla
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What are the structures of the limbic system?
- cortical: cingulate gyrus, parahippocampal gyrus, hippocampal formation, orbital & prefrontal cortex (extended)
- Subcortical: amygdala, septal region, ventral basal ganglia including nucleus accumbens, basal forebrain(extended)
- Diencephalic & Brainstem: thalamic nuclei, hypothalamus (mamillary bodies), reticular formation(extended)
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What sensory input directly goes into the limbic system?
- olfactory into amygdala
- emotions from smell
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Where is the amygldala located?
anterior, medial aspect of temporal lobe
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What are some important connections of the amygdala?
- olfactory striae
- thalamus & hypothalamus (ventral amygdalofugal)
- stria terminals (septal)
- cortex
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What does the stria terminalis connect?
amygldala & septal areas
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What does the fornix connect?
reciprocal projections between hippocampus & mammilalary nuclei (& septal area)
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What does the amygdala do?
- fear
- assign emotional significance to sensory experience
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Where is the hippocampus?
medial temporal, posterior to amygdala
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What are the features of the hippocampus?
- dentate gyrus (new memories)
- hippocampus proper: Corni ammonis(CA1, CA3)
- subiculum
- CA1
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What is the papez circuit?
- 1. Hippocampus
- 2. Fornix
- 3. Mamillary body
- 4. Anterior nucleus of dorsal thalamus
- 5. Cingulate Gyrus
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What does the hippocampus do?
formation of new declarative memory (episodic & semantic) NOT nondeclarative (procedural)
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What is special about the dentate gyrus?
- Neurogenesis of hypoxic sucsceptible hippocamus
- could lead to improper circuit loops-> epilepsy
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What is epilepsy?
spontaneous seizures (excessive synchronous neuronal activity of brain)
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What is MTLE?
- Mesial Temporal Lobe Epilepsy
- often w/ hippocampal sclerosis
- recurring seizures -> depression
- most resistant to therapy (unless surgical removal)
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What is seizure first aid?
- prevent injury
- supine
- do not restrain or put anything in mouth
- note duration
- call 911 (> 5 mins or other complications)
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What are mechanisms of antiepileptic drugs?
- (prevent hyperexcitability)
- determined by type of seizures (partial, gereralized)
- Voltage gated Na+ channel (phenytoin: SE gingival hyperplasia)
- Ca2+ channel
- GABA, AMPA NMDA receptors
- Glutamergic blockers
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What are dental implicatioins of antiepileptic drugs?
- sedatives: CNS depressiion
- gingival hyperplasia: phenytoin, eithosuximide
- hepatic microsomal enzyme induction
- orofacial pain treatment: gabapentin
- migrane treatment
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What are non drug treatments of epiliepsy?
- surgery: removal of epileptogenic region
- elecctrical stimulation: vagal, trigeminal nervestimulation
- ketogenic diet
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What are common side effects of anti-seizure meds?
- increased infection
- xerostomia
- gingival hyperplasia (phenytoin)
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what is the main function of the basal ganglia?
gating proper initiation of movement
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What are the components of the basal ganglia?
- caudate nucleus & putamen: striatum
- globus pallidus: external & internal
- substantia nigra: parscompacta & pars reticulata
- subthalamic nucleus
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What 2 systems modulate motor system?
- basal ganglia: gating proper initiation of movement
- cerebellum: sensory motor coordination
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What regions project (input) to basal ganglia?
- cortex
- frontal(medial)->caudate
- temporal, parietal, frontal (lateral)-> putamen
- primary visual cortex
- primary auditory cortex
- PARS COMPACTA (nigrostriatal pathway)
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What is the importance of the nigrostraiatal pathway?
dopamine modulatory neurotransmitter: pars compacta of substantia nigra to striatum
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What are the 3 parts of the hypothalamus?
- anterior: reproduction & thermoregulation
- Tuberal: hypophysiotrophic zone (anterior pituitary)
- posterior/lateral: state & arousal mechanisms
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What are the humeral(blood) inputs to the hypothalamus?
- thermo/osmo, hormone receptors
- circumventricular organs: along ventricles w/o blood-brain barrier
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What are control mechanisms of hypothalamus?
- 1. neural signals: ANS (lateral) parasym vagal nuclei & IML
- 2. endocrine: pituitary
- a. magnocellular: posterior pituitary-release neurohormomes into bloodstream
- b. parvicellular: median eminaence: secrete releasing factors into capillary system of anterior pituitary
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