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What are the four parts of the diencepthalon?
- Epithalamus
- Dorsal Thalamus
- Ventral Thalamus
- Hypothalamus
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What are the boundaries of the hypothalamus?
- Rostral: lamina terminalis, anterior commissure
- Dorsal: hypothalamic sulcus
- Ventral: optic chiasm and base of brain
- Caudal: posterior to mammillary bodies
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What are the four hypothalamic regions?
- Pre-Optic Area
- Anterior Supraoptic Area
- Middle Tuberal Region
- Posterior Mammillary Region
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What are the 3 zones medial to lateral in the hypothalamic regions?
- Periventricular continuous with PAGMedial mostly nucleiLateral lateral hypothalamic nucleus, traversed by the medial forebrain bundle (MFB)
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What structures does the anterior (supraoptic) region house?
- 1. Periventricular
- 2. supraoptic nuclei
- paraventricular nuclei
- suprachiasmatic nuclei
- anterior nuclei
- 3. Lateral Hypothalamus
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What structures does the middle (tuberal) region of the hypothalamus house?
- 1. Periventricular
- 2. arcuate nuclei
- ventromedial nuclei
- dorsomedial nuclei
- 3. Lateral hypothalamus
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What structures does the Posterior (mammillary) region house?
- 1. Periventricular
- 2. mammillary bodies
- posterior nuclei
- 3. Lateral hypothalamus + MFB
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What structures does the Preoptic Region house?
- 1. Medial preoptic nucleus
- 2. Lateral preoptic nucleus MFB
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What is the function of the preoptic nuclei?
Male sexual behavior
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What is the function of the periventricular areas of the anterior/middle/posterior regions of the hypothalamus?
feeding behaviors
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What is the purpose of the suprachiasmatic nuclei of the anterior region of the hypothalamus?
necessary for diurnal cycles (retinal axons terminate here)
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What is the purpose of the supraoptic and paraventricular nuclei?
- to project to the posterior pituatary andcan make ADH and oxitosin
- ALSO paraventricular contributes to the Central Sympathetic Tract
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What does the anterior nucleus do?
thermoregulation
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What does MFB stand for?
medial forebrain bundle = activating behaviors such as feeding, sexual, etc
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What does the lateral hypothalamus of the anterior and middle regions of the hypothalamus do?
activate the limbic system
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What does the arcuate nucleus of the middle tuberal region do?
projects to the anterior pituitary gland via a venus plexus (no direct connection)
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What does the ventromedial part of the middle tuberal region of the hypothalamus do?
feeding, rage, female sexual behavior
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What does the dorsal medial nucleus of the middle region of the hypothalamus do?
regulates ingestive behavior
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What does the posterior nucleus of the posterior region of the hypothalamus do?
contributes to the central sympathetic tract
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Which parts of the hypothalamus project to the central sympathetic tract?
- Paraventricular region of the Anterior Region of the Hypothalamus
- Posterior nucleus of the Posterior Region of the Hypothalamus
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What two nuclei feed information to the anterior and posterior pituitary glands respectively?
- Arcutate nucleus of the middle region of the Hypothalamus
- Supraoptic and Paraventricular of the anterior region of the Hypothalamus
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The MFB (Median Forebrain Bundle) carries many fibers through the hypothalamus and even contributes with reciprocal connections. What two structures outside of the hypothalamus does the MFB connect?
- Brainstem
- Septum/Amagdala/Telencephalon
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To which part of the hypothalamus do fornix fibers contribute?
Mammillary Bodies
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What are three parts of the amygdala?
- Cortical Medial Amygdala
- Central Amygdala
- Basal Lateral Amygdala
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What fibers feed into the suprachiasmatic nucleus?
Retinal fibers
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Some of the Paraventricular nuclei and most of the Supraoptic nuclei make up the input to the posterior pituitary. What do these cells produce and how does it reach the posterior pituitary?
- ADH (anti-duretic hormone) and Oxytocin
- This reaches the posterior pituitary via axonal transport and releasing of the chemicals into the capillary beds
- This then migrates to kidney, uterus, and breasts
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What does the arcuate nucleus contain?
- many clusters of cells that make different factors that are directed for the anterior pituitary
- these factors include hypothalamic releasing hormones and release-inhibiting hormones
- an example of a release-inhibiting hormone used in class was dopamine which inhibits pro-lactin release
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What are the 7 hypothalamic regulatory hormones released by the arcuate nucleus?
- GHRH: Growth Hormone Releasing Hormone
- GHIH: Growth Hormone Inhibiting Hormone
- PRH: Prolactin Releasing Hormone
- PIH (dopamine): Prolactin Inhibiting Hormone
- CRH: Corticotropin Releasing Hormone
- TRH: Thyrotropin Releasing Hormone
- LHRH/FRH: Luteinizing Hormone Releasing Hormone/Follicle-Stimulating Releasing Hormone
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GHRH
Anterior Pituitary Hormone
Functional Result
- increase in Growth Hormone
- stimulates linear growth in epiphyseal cartilages
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GHIH
Anterior Pituitary Hormone
Functional Result
- reduction in production of growth hormone
- reduces linear growth in epiphyseal cartilages
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PRH
Anterior Pituitary Hormone
Functional Result
- increase in prolactin
- stimulates lactogenesis
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PIH (dopamine)
Anterior Pituitary Hormone
Functional Result
- decrease the production of prolactin
- reduces lactogenesis
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CRH
Anterior Pituitary Hormone
Functional Result
- adrenocorticotropic hormone
- stimulates adrenal gland to produce corticosteriods and sex hormones
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TRH
Anterior Pituitary Hormone
Functional Result
- Thyroid Stimulating Hormone
- stimulates thyriod gland to produce thyroxine
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LHRH/FRH
Anterior Pituitary Hormone
Functional Result
- Lutenizing Hormone
- Follicle-Stimulating Hormone
- stimulates ovarian follicles and production of estrogen and progesterone
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What effect does dopamine have when released from the Arcuate nucleus of the middle region of the hypothalamus and goes to the anterior pituitary?
suppresses the secretion of pro-lactin
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What effect does serotonin have on the anterior pituitary?
Increases secretion of prolactin
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Patient X comes in and is pyschotic, so you give them a dopamine D2 blocker. What side effects should you be concerned about as a result of drug interactions in the hypothalamus/anterior pituitary if X is a male? What if X is a female?
- Male: decrease in libido, impotence, infertility, and in a few rare, but exciting cases, galactorrhoea and gynaecomastia (breast enlargement)
- Women: galactorrhea, irregular menses, decreased libido, infertility
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What four places do the mitral and tufted cells of the olfactory nerve project to?
- Corticomedial Amygdala
- pyriform/olfactory cortex
- septum
- substantia innominata/anterior perforated substance
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What should we know about the limbic overview circuitry?
Everything is connected to everything!
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What is a common target of the Herpes (HSV1 (adults) & HSV2 (children))? What will likely be affected?
- Anterior Cingulate Gyrus of the limbic cortex
- processing of emotion and short term memories
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What does Hippocampus mean in Greek?
Sea Horse
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What are the four main components of the Hippocampus?
- Dentate Gyrus
- Hippocampus
- Subiculum
- Parahippocampal Gyrus
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What is the function of the Hippocampus?
- consolidation of short term memory into long term memory
- The hippocampus is the index of sorts for memory
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What is the breakdown on percentages of people and their hippocampi after they reach 60 years old?
- 30% entorhinal area compromised due to Alzheimers
- 30% subiculum compromised and they have benign senescent forgetfullness
- 40% show healthy aging----hopefully me!
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Where do most of the sensory areas feed into in the hippocampus?
Entorhinal cortex
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What good is the Papex Circuit?
short term memory (up to 2 minutes)
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What structures comprise the Papez Circuit?
- Entorhinal cortex
- Dentate gyrus/Amon's Horn
- Mammillary Bodies
- Mammillothalamic Tract
- Anterior Thalamic Nucleus
- Cingulate Gyrus
- Internal Capsule
- Fornix
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What is the part of the Amygdala that deals mainly with fear?
The central Amygdala
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What part of the Amygdala gives correlation between emotion and vision/sounds?
Basolateral Amygdala
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If you suffer a lesion in the Amygdala, what will happen to you as far as sex, eating, and mood?
- Hypersexual
- Eat a lot
- Be Aggressive
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If you suffer a lesion in the septum, what's going to happen to you?
Low levels of limbic activity: no sex, no eating, no motivation/aggression
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33-year-old neurology resident with a history of migraine fell backward while
attempting a ski jump, struck his occiput on the snow, and suddenly developed amnesia.
He began asking the same questions repeatedly, was unable to retain any new
information for more than 1 to 2 minutes, and he did not recall any events that
had occurred during the previous approximately 1 year. After about 5 hours memories began to return
gradually, with the most remote memories generally returning first.
Location?
medial temporal or part of Papez circuit, bilaterally.
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A 40-year-old right-handed woman came to the emergency
room because of unusual episodes of an indescribable unpleasant odor, nausea,
and a panicky, fearful sensation. This lasted for 2 to 3 minutes, after which
she felt very tired and went back to sleep. During the following week episodes
increased, followed by decreased responsiveness and slow, inappropriate speech
lasting 2 to 3 minutes. After each episode she had a bifrontal headache
and tiredness.
Location?
- Unpleasant odor, nausea, and a panicky,
- fearful sensation?Amygdala and
- adjacent cortical areas.
- Decreased responsiveness and slow,
- inappropriate speech? Left hemisphere, amygdala and
- adjacent areas and/or secondary cortical involvement.
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