Hypothalamus and Limbic System Flashcards
Location of the Hypothalamus
And part of what anatomically
Part of what functionally
Inferior to the Thalamus and forms the walls and floor of the 3rd ventricle
The Diencephalon
The Limbic System
The Hypothalamus regulates what
- Basic drives (motivation, goal directed behavior, emotional behavior)
- Homeostasis, ANS, and endocrine function (food intake, body temp., electrolytes balance, sexual behavior, sleep/wake cycle)
The Hypothalamus: Anterior (rostral) Posterior (Caudal) Floor and wall of Continuous with
Optic Chaism
Merges into the tegmentum and PAG (midbrain)
3rd ventricle
Through the infundibular stalk with the posterior Pituitary
3 Parts of the Hypothalamus
- Mammillary Bodies
- Tuber Cinereum
- Median Eminence
Mammillary Bodies
Posterior part of hypo. Next to the cerebral peduncles (bulb)
Tuber cinereum
Small swelling between the mammillary body and the optic chiasm and the tract
Median Eminence
Arises from the tuber cinereum and narrows into the the infundibulum which attaches to the PP
The Medial Zone
Anterior Zone
Anterior Area:
- Paraventricular Nucleus
- Preoptic Nucleus
- Anterior Nucleus
- Superaoptic Nucleus
- Suprachiasmatic Nucleus
The Medial Zone
Middle/ Tuberal Area
- Arcuate Nucleus
- Ventromedial Nucleus
- Dorsomedial Nucleus
The Medial Zone:
Posterior Area
Posterior Area:
- Posterior Nucleus
- Mammillary Body
Lateral Zone:
diffusely arranged neurons
Median Forebrain Bundle (sends info to and from the hypo.)
Damage can cause (decrease in feeding, weight loss)
Supraoptic/paraventricular Nucleus
Function
Lesion
Contains oxytocin (PVN) & ADH (SON) = goes to PP Lesion: Diabetes Insipidus- high H2O intake and high urination
Suprachiasmatic Nucleus
Function
Lesion
Gets input from retina and helps with sleep and wake cycle (circadian rhythm)
Lesion: change or loose Circadian rhythm
Anterior Nucleus
Visceral and Somatic Functions and Temperature Regulation
Ventromedial Nucleus
Function
Lesions
“Satiety center”
Lesion: excessive eating and weight gain
Dorsomedial Nucleus
Function
Lesion
Serves emotional behavior, (sham rage)
Lesion: low aggression and feeding
Arcuate Nucleus
Function
Secretes releasing and inhibiting hormones
Medial Mammillary Nucleus
Function
Lesion
AFFERENTS= to the hippo. by the (Fornix)
EFFERENTS=to the thalamus and brainstem
Lesion: no short-term memory, can’t process short term events= no long term memory
Blood Supply to hypothalamus comes form
Circle of Willis
Anteriomedial group of branches from the Circle of Willis
Come from where
Supply what
From the Ant. Communicating A. And ACA (A1) Goes to the 1 preoptic area, 2 supraoptic region, 3 septal nuclei, and 4 rostral part of lateral hypothalamus
Posteromedial group of branches from the Circle of Willis
Come from where
Supply what
Posterior Communicating A and PCA (P1)
Rostral part of Post. Communicating A -> Tuberal Region (middle zone)
Caudal part of Post. Communicating A-> Mammillary Region. (Posterior zone )
Fornix connects
Hippocampal fibers form the to the Mammillary Bodies
Brings information form the hippocampus to its mammillary bodies
Stria Terminalis an Ventral amygdalofugal fibers connects
Amygdala to Hypothalamus
Corticohypothalamic input connects
Orbitofrontal & cingulate areas &multiple association areas, frontal lobe—-> Lateral Zone of the Hypothalamus
Retinohypothalamic fibers connects
Retina to the Suprachiasmatic Nucleus (SCN) form sleep wake cycles
Median Forebrain Bundle (MFB) and Dorsal Longitudinal Fasciculus (DLF)
Sends to where
From the hypothalamus and to the hypothalamus also
Form hypo GOES TO PAG and RF ——>
1. Hypothalamomedullary fibers
2. Hypothalamospinal fibers
3. Medial zone and mammillary bodies (posterior zone)
TO REGULATE EMOTIONAL BEHAVIOR
Hypothalamocortical fibers
From the hypothalamus GOES TO the forebrain FRONTAL LOBE
Mammillothalamic Tract
From the Hypo GOES TO anterior nucleus of Thalamus (which sends info to the frontal lobe)
Lateral Zone fibers
From the Hypothalamus GOES TO Dorsomedial nucleus of Thalamus (which sends information to the frontal lobe)
Hypohypophyseal interaction
Hypothalamus and pituitary gland
Supraopticohypophyseal Tract
Axons from the SON and PVN (supraoptic and paraventricular)——> PP (Herring bodies),
Release oxytocin and ADH in the herring bodies that are surrounded by capillary plexuses inside which send H to blood stream
Tuberoinfundibular Tract
Axons from PVN and paraventricular zone ——> AP (median eminence and infundibulum) where the Hs are released on these cells
These cells then secrete H out to the blood stream
ANS is regulated by what parts of hypothalamus
Anterior and Posterior areas
Anterior Area of Hypothalamus (ANS)
Activates PARASYMPATHETIC NEURONS (REST AND DIGEST)
Goes to brainstem with CN3, 7, 9, 10 (parasympathetic)
Goes to S2-S4 with spinal neurons
Posterior Area of Hypothalamus (PNS)
Activates SYMPATHETIC neurons (FIGHT OR FLIGHT)
Goes to T1-L2 lateral horn as sympathetic neurons
Ex: hypothalamomedullary fibers: sympathetic outflow to face and head from the medulla
Lesion in the anterolateral medulla
Disrupts the hypothalamomedullary fibers
HORNERS SYNDROME
Sympathetic fibers to face and head and body is disrupted
(Dilated pupil, anhydrosis)
SCN
Gets input from
Mediates
Function
From the retina
Circadian rhythm and the hormonal fluctuations of dark/light cycles
OPPOSE SLEEP for timing of rest vs activity
How are circadian genes controlled
Transcribed and translated every 24hrs——> control melatonin release from PINEAL GLAND——-> SLEEP ONSET
Feedbacks to the SCN
Limbic System
Includes
Gets input from
Function
- Subcallosal Area
- Parahippocampal gyrus
3.Cingulate Gyrus - Hippocampal formation
- Subcortical Nuclei (hippo., Amygdala, septal nuclei)
6.Uncus
Input from diverse areas of Brian
For MEMORY, PAIN PERCEPTION BEHAVIOR
—-> led to Pepez circuit
Paper Circuit
First description of anatomicaophyologic mechanism for emotion
How to tie our memory and emotions to behavior
We eat the food we like, and how to see exactly what brain area is involved with that
Hypothalamus +Limbic System
anatomical basis for emotional and drive-related, and motivation behavior
Hippocampal Formation
Learning and memory In temporal lobe is curved formation 1. Subiculum 2. Hippocampus proper (ammon horn) 3. dentate gyrus 4. Parahippocampal gyrus (entorhinal cortex) overlies all the other ones
Hippocampal formation Afferent pathway
Dentate gyrus —-> CA3 —-> CA1—->Subiculum
CA= cormus ammonis (horn)
Hippocampal Formation Efferents pathway
fibers from cell bodies in the subiculum CA2 and hippocampus proper CA1—-> fornix as the fimbria ——> mammillary bodies, VMN, Anterior (dorsal) nucleus of thalamus
Uncal Herniation
due to hemorrhage or tumors
Uncus and parahippocampal gyrus move down over the tentorium cerebelli edge —-> compresses the midbrain and later other Brian stem areas
CAUSES: dilated pupils, X CN3, SAME SIDE
OPPOSITE weak Extremities
If continued you have loss of reflex, resp. And rapid decline
Korsakoff Syndrome
Degeneration of the mammillary bodies, DMN, Hippocampal complex
NO LONG-TERM MEMORY made form short term
Can’t learn new tastes, and have meaningful conversations, CONFABULATES (makes up random events that never happened from combining random memories)
Thiamine deficiency of chronic alcoholics
Hippocampal Amnesia
Bilaterally lesions of hippocampus
X: anterograde episodic memory (can’t learn new tasks)
CAN STILL have procedural and working memory (short-term) and IQ and formal reasoning is still fairly normal
Olfactory Disorders due to the hypothalamus:
Anosmia
X: smell due to viral infection of olfactory mucosa or obstruction of nasal passages (CN1 lesions, anterior cranial fossa tumor), or congenital
(Don’t recover sence of smell)
Olfactory Disorders due to the hypothalamus:
Phantomia (olfactory hallucination)
Distortion in a smell experience and smelling something when there is no odor present
Abnormal neural activity
ANTERIOR, MEDIAL Temporal lobe lesions (Hippo, amygdala, medial dorsal thalamus)
Amygdala
Reward, emotional learning and memory, fear and conditioning
Makes an emotional attachment,
Response to stimulus like pain
Emotional response to food
Amygdala input
From the raphe nuclei, PAG, CN10 motor nuclei, nucleus solitaries, and locus ceruleus
Input from the DMN thalamus
Amygdala fibers go to
AFFERNTS TO THE HYPOTHALAMUS (Stria terminalis, ventral amygdalofugal pathways)
Also to the cortex frontal cingulate and temporal
Amygdala Lesions
No fear, anger, disgust in facial expression and in how you actually feel, and can’t recognize it in other people
Kluver-Bucy Syndrome
Bilateral lesion of amygdala
- Visual Agnosia= can’t recognize an object by sight
- Hypermetamophosis= compulsion to overexplore the envr. + overreact to visual stimulus
- Hyperorality= examine objects by mouth
- Placidity=no fear or anger in appropriate situations
- Hyperphagia=eat a lot even when not hungry or not food objects
- Hypersexuality= inappropriate sexual acts and talks
The Papez Circuit pathway
- Fornix —> mammillary bodies
- Amygdala adds to the hypothalamus also (emotional memory, emotions, basic drive)
- ——>Thalamus anterior nucleus (mammillothalamic tract)—-> cingulate cortex
——> prefrontal cortex —-> association cortex - Hippocampus
Neuroanatomical circuit of emotion between the Limbic system and cortical areas of the brain
Ventral Tegmental Area
Had dopaminergic neurons ( located medial to substantia nigra)
REWARD ,MOTIVATION, ADDICTION
GETS info from the prefrontal cortex
SENDS info from the nucleus accumbants, and septal nuclei, Amygdala, and prefrontal cortex
Septal Nuclei
Rostral to anterior commissure
Connects to olfactory bulb and hippocampus and amygdala (BY FORNIX)
REWARD, PLEASURE, RAGE BEHAVIOR
Nucleus Accumbens
forebrain near caudate and putamen
ADDICTION, and CHRONIC PAIN behaviors
