3 longitudinal zones (paraventricular, medial, longitudinal)

4 rostro-caudal regions

Distinct nuclei that don't really adhere to these boundaries very well.

Sensory information, esp. visual and olfactory

Brainstem, other limbic info

Blood info (circumventricular organs)

control many homeostatic, neuroendocrine, and behavioral functions

Especially Neuroendocrine, thermoregulation, fluid homeostasis, feeding, reproduction

Clearly controls the pituitary gland

Located along the 3rd ventricle

contains parvo+magnocellular neurosecretory neurons

Main nuclei are the periventricular nucleus and the arcuate nucleus

controls ADH release (vasopressin)

Above the optic nerve, in the periventricular zone

Receives direct input from the retina (retinal-hypothalamic tract) and modulates circadian rythyms.

Above the optic chiasm in the periventricular zone.

Adjacent to the periventricular zone, recieves a lot of input from the amygdala, limbic system.

Main nuclei are the mammilary bodies, dorsomedial and ventromedial nuclei, and the medial preoptic nucleus.

Involved in memory (limbic system)

At the ends of the fornix.

Regulate food intake.

Located in the medial zone of the hypothalamus.

thermoregulation primarily, but also hypovolemic thirst, sex, and blood pressure

Before the optic nerve, in the medial zone of the hypothalamus

No distinct nuclei, lots of fibers of passage, poorly differentiated,

like a router bundle

Ventral amygdalofugal  (amygdala)

Strial terminalis

Hippocampus

only organ to not have blood brain barrier, thus communicate blood borne signals to reach chemosensitive neurons

8 major organs, Median Eminence the most prominent (controls hypothalamic-pituitary effect  on target effect organs)

mammillothalamic tract (part of the Papez circuit)

hypothalamus to thalamus

Mamillary bodies deal with memory

hypothalamomedullary tract

dorsal longitudinal fasciculus is a part of this area.

hypothalamospinal tract

Paraventricular nucleus + supraoptic nucleus produces oxytocin and ADH (magnocellular)

transported to posterior pituitary via tuberohypophyseal tract axonal transport

Posterior pituitary releases oxytocin and ADH

Fast acting

neural tissue, not endocrine tissue

more homogeneous than the anterior pituitary

Magnocellular input

promotes water reabsorption in the collecting ducts of the kidneys

can act as a vasoconstrictor during hemorrhage

ADH secretion is impaired from excessive drinking and urination

Lack of ADH -> Central Diabetes inspidus

Lack of response to ADH in kidnets -> Nephrogenic Diabetes insipidus

Milk ejection

Birth contractions

Maternal and affiliative behavior

Longer pup retrieval time (mom doesnt care)

No feeding in new mothers

increased affiliative behavior

cohabitation of prairie dogs creates a partner preference when injected

Nucleus accumbens is important

incrased gaze on the eye regions

implies social connections, empathy

social cues are more salient

Parvocellular neurons in the arcuate nucleus project to the anterior pituitary

anterior pituitary releases factors into the median eminence

eminence contacts capillaries at the portal plexus

1. Factors relasesd in hypothalamus (Guilleman & Schally 1977 nobel) target specific cell bodies in pituitary

2. pituitary releases hormones

3. Organ produces a horomone

4. Feedback (neg. usually) to hypothalamus

5. Pulsatile release of hormone

Produced in parvocellular cells of the paraventricular nucleus

Produces TSH in the pituitary

there are thyroid hormone sensors back in the paraventricular nucleus

hypothyroid -> weight gain, skin dry, swelling, hair loss

hyperthyroid -> weight loss, skin wet, anxiety

Growth Hormone Releasing hormone is produced in the arcuate nucleus, Somatostatin is produced in the periventricular hypothalamus

produce growth hormone in the pituitary, which stimulates bone growth and IGF in the liver

Negative feedback of Growth hormone on itself via stimulation of somatostatin production, which inhibits Growth hormone

Dwarfism, giantism

corticotropin releasing hormone is produced in the paraventricular nucleus (parvocellular)

acts on pituitary to release ACTH, providing stress responses, energy utilization

Overactive -> Cushings

Underactive -> Addison's

Overexposure can cause hypothalamic damage, immunosuppressant

Created in anterior hypothalamus

targets pituitary, releases Leutinizing hormone and follicle stimulating hormone. Acts on gonads

Feedback is neg+pos in humans, through estrogen receptors in the brain. Fertility drugs inhibit the neg. feedback, allowing more LH and FSH to be produced

stimulates secretion of sex steroids in the gonads

Birth control pills block LH

Ovulation of mature follicles is induced by a lot of LH

Created in the arcuate nucleus, frome dopamine

starts milk production, contributes to milk letdown

Weight setpoint

Synthesized in fat tissue, receptors in arcuate, ventromedial, and paraventricular nuclei

lack leptin -> overeat, treatable

lack receptor -> overeat, untreatable

Ghrelin is the hunger setpoint.

Made by the stomach, Found in the blood, receptors in arcuate nucleus, acts at NPY receptors

opposes leptin 

NPY/AgRP

rexigenic (increases feeding)

NPY synthesized everywhere, and AgRP in Arcuate nucleus only

NPY short acting, AgRP acts over 6 days

AgRP blocks MC3, MC4 (stop eating) receptor function

alpha-MSH/CART

produced in arcuate

decrease feeding

Sham Rage

Defensive behavior, stimulate the ventromedial hypothalamus

Leisions of dorsal premammillary nucleus produce passive behavior

anterior hypothalamic lesion produces mixed defensive behavior