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Boundaries of the Diencephalon:
Anterior
Posterior
Floor
Roof
Medial
Lateral
- Anterior: anterior commissure & optic chiasm
- Posterior: pineal gland
- Floor: posterior commissure & hypothalamus
- Roof: fornix
- Medial: wall of 3rd ventricle
- Lateral: internal capsule & tail of caudate nucleus
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Regions of the Diencephalon
- 1. Epithalamus
- 2. Subthalamus
- 3. Thalamus
- 4. Hypothalamus
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Components of the epithalamus?
Pineal gland & Habenular nuclei
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Habenular Nuclei
What system does it belong to?
Afferent Input?
Efferent Output?
- Involved in limbic system relays
- Afferent Input:
stria medullaris thalami - Efferent Output: interpeduncular nuclei
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Pineal Gland Contents
- 1. pinealocytes
- 2. glial cells
- 3. rich vasculature
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Pineal Gland Function
- - regulates circadian rhythms by levels of melatonin
- - high during darkness, low during light
- - activity regulated by light from retina
- - antigonadotropic effect
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Pathway of Pineal Gland Activity
- 1. Retina
- 2. Suprachiasmatic Nucleus (SCN-hypothalamus)
- 3. Reticular formation in ventrolateral medulla
- 4. Intermediolateral neurons of sp. cord
- 5. Superior cervical ganglion
- 6. Pineal Gland
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Circumventricular Organ
organ that lacks a blood brain barrier
ex: pineal gland
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Contents of the Subthalamus
- 1. Subthalamic nuclei (STN)
- 2. Zona Incerta (ZI)
- 3. Rostral extensions of Red Nucleus & Substantia Nigra (SN)
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Subthalamus:
Function of subthalamic nucleus?
part of basal ganglia circuitry; related to motor systems
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Subthalamus:
Function of the Substantia Nigra?
2 parts: pars compacta & pars reticularis; related to motor systems
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Subthalamus:
Function of Zona Incerta?
widespread & unknown
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Thalamus:
Regions & Nuclei?
- 1. Anterior: anterior n.
- 2. Medial: dorsal medial n.
- 3. Lateral:
- ventral: VA, VD, VPM, VPL
- dorsal: Pulvinar, LP, LD
- metathalamic: MGB, LGB
- intralaminar: centromedian & parafascicular n.
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Thalamus:
Specific nuclei vs. Non specific nuclei
- Specific: Anterior, VA, VL, VPM, VPL, LGB, MGB
- Non specific: DMN, Pulvinar, LP
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Thalamus: LGN
Major input?
Major output?
Function?
- Thalamus: LGN
- Major input? optic tract
- Major output? visual cortex (17)
- Function? vision
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Thalamus: MGN
Major input?
Major output?
Function?
- Thalamus: MGN
- Major input? Inferior colliculus (IC)
- Major output? Auditory Cortex (41, 42)
- Function? Hearing
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Thalamus: VPL
Major input?
Major output?
Function?
- Thalamus: VPL
- Major input? Medial Lemniscus & Spinal Thalamic Tract
- Major output? Somatosensory Cortex (3,1,2)
- Function? T/P/P & P/T (body)
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Thalamus: VPM
Major input?
Major output?
Function?
- Thalamus: VPM
- Major input? Trigeminothalamic tract & solitary n.
- Major output? Somatosensory (3,1,2)
- Function? T/P/P & P/T (face)
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Thalamus: VL
Major input?
Major output?
Function?
- Thalamus: VL
- Major input? dentate n., substantia nigra, globus pallidus
- Major output? Motor (4) & Pre motor (6)
- Function? movement
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Thalamus: VA
Major input?
Major output?
Function?
- Thalamus: VA
- Major input? globus pallidus, substantia nigra
- Major output? motor (4) & pre motor (6)
- Function? movement
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Thalamus: Anterior
Major input?
Major output?
Function?
- Thalamus: Anterior
- Major input? hippocampus, mammillothalamic tract
- Major output? cingulate gyrus
- Function? emotion & memory (limbic)
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Thalamus: LD
Major input?
Major output?
Function?
- Thalamus: LD
- Major input? hippocampus
- Major output? cingulate gyrus
- Function? emotion & memory (limbic)
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Complex Connectivity of Hypothalamus
- 1. interconnection w/limbic system
- 2. output to pituitary
- 3. interconnection w/bisceral & somatic nuclei of brainstem & spinal cord
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Longitudinal Regions of Hypothalamus
- 1. Periventricular zone
- 2. Medial zone
- 3. Lateral zone
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Regions of the Hypothalamus
- 1. Posterior
- 2. Tuberal
- 3. Anterior
- 4. Preoptic
- 5. Lateral
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Nuclei of Hypothalamus:
Posterior Area
- Mamillary Body: learning & memory
- Posterior N.: thermoregulatory
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Nuclei of Hypothalamus:
Tuberal Area
- Arcuate n.: makes Grehlin--> increases food intake & dopamine release
- VMN: ant-larger in females; sup-satiety
- DMN: hyperphagia & wakefulness (orexin)
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Nuclei of Hypothalamus:
Anterior Area
- Supraoptic N. (2): regulate water balance
- Paraventricular N.: " " "
- Anterior N.: thermoregulatory
- Suprachiasmatic N. : controls biological clock
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Nuclei of Hypothalamus:
Preoptic Area
Preoptic N.: larger in males (mounting)
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Nuclei of Hypothalamus:
Lateral Area
Lateral N.: feeding center (pleasure)
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