Hypothalamic and Limbic Systems

Question 1

What is the function of the hypothalamus?

Answer 1

Integrates information from forebrain, brainstem, and spinal cord; primary role is maintenance of homeostasis (water/electrolyte balance, food intake, temperature, BP, circadian rhythm, stress responses, and body metabolism)

Question 2

Where are mammillary bodies found?

Answer 2

Form posterior part of the hypothalamus and are adjacent to cerebral peduncles

Question 3

What is the tuber cinereum?

Answer 3

Small swelling between the mammillary bodies and the optic chiasm and tract

Question 4

What is the median eminence?

Answer 4

Arises from the tuber cinereum and narrows into the infundibulum, attaches to pituitary gland

Question 5

What are the longitudinal divisions of the hypothalamic nuclei?

Answer 5

Anterior region, tuberal region, mammillary/posterior region

Question 6

What are the medial to lateral divisions of the hypothalamic nuclei?

Answer 6

Periventricular zone and fornix

Question 7

Where is the anterior region of the hypothalamus?

Answer 7

Superior to optic chiasm, extending anteriorly to the lamina terminalis

Question 8

Where is the tuberal region of the hypothalamus?

Answer 8

Superior to and including the tuber cinereum

Question 9

Where is the mammillary/posterior region of the hypothalamus?

Answer 9

Superior to and including the mammillary bodies

Question 10

Where is the periventricular zone of the hypothalamus?

Answer 10

Periaqueductal gray (midbrain) through the wall of the 3rd ventricle

Question 11

What is the fornix of the hypothalamus?

Answer 11

Used to divide the remainder of hypothalamus into medial and lateral zones

Question 12

What is the lateral zone of the hypothalamus?

Answer 12

Diffusely arranged neurons with few named nuclei; contains the median forebrain bundle; damage results in a decrease in feeding behavior with a resultant weight loss

Question 13

What is the medial zone of the hypothalamus?

Answer 13

Medial zone overlaps with anterior —–> posterior regions, where neurons are arranged in distinct nuclei

Question 14

What is the supraoptic/paraventricular nucleus in the hypothalamus? What do lesions result in?

Answer 14

Contains oxytocin and ADH (PVN) —-> posterior pituitary; lesions can result in diabetes insipidus (DI), increased H2O intake, and increased urination

Question 15

What is the suprachiasmatic nucleus in the hypothalamus?

Answer 15

Receives retinal input and is involved in circadian rhythms; damage to this area may modify, or abolish, these rhythms

Question 16

What is the function of the anterior nucleus of the hypothalamus?

Answer 16

Range of visceral/somatic functions, temperature regulation

Question 17

What is the function of the medial mammillary nucleus of the hypothalamus? What do lesions cause?

Answer 17

Afferents from the hippocampus via the fornix; efferents to the thalamus & brainstem; lesions result in an inability to process short-term events —-> long-term memory

Question 18

What is the function of the ventromedial nucleus of the hypothalamus? What do lesions cause?

Answer 18

Considered to be a “satiety center”; lesions causes excessive eating and abnormal weight gain

Question 19

What is the function of the dorsomedial nucleus of the hypothalamus? What does destruction cause?

Answer 19

Subserves functions of emotional behavior; stimulation causes sham rage; destruction results in less aggression and feeding

Question 20

What is the blood supply to the hypothalamus?

Answer 20

Perforating branches from circle of willis (from anterior communicating, A1, posterior communicating, P1)

Question 21

What is the suprachiasmatic nucleus?

Answer 21

Receives direct input from the retina to mediate circadian rhythms, hormonal fluctuations secondary to light-dark cycles; conveys circadian info to other hypothalamic regions, influencing sleep-wake transitions

Question 22

What does suprachiasmatic nucleus activity cause?

Answer 22

Opposes drive for sleep, is essential for timing of rest vs activity

Question 23

What is the function of the limbic system?

Answer 23

Connections influence behavior, memory, and pain perception

Question 24

What is the function of the hippocampal formation?

Answer 24

Important in learning and memory

Question 25

What is the function of the amygdala?

Answer 25

Vital to the motivational and emotional connotations of experience

Question 26

What is the function of the Papez circuit?

Answer 26

Oversimplification of the role of limbic system plays in modulating feelings (fear, anxiety, sadness, happiness, etc)

Question 27

What is the septal region?

Answer 27

Small area just rostral to the anterior commissure thought to control of rage behavior

Question 28

What is the medial forebrain bundle?

Answer 28

Diffuse group of dopaminergic fibers that courses rostrocaudally through the lateral hypothalamic area; major conduit for septal nuclei and hypothalamus to communicate with the brainstem

Question 29

What is the nucleus accumbens?

Answer 29

Receives input from the amygdala and hippocampus; play an important role in behaviors related to addiction and chronic pain; efferents include hypothalamus, brainstem, and globus pallidus

Question 30

What is hippocampal amnesia?

Answer 30

Bilateral lesions of the hippocampi; causes profound deficit in anterograde episodic memory (cannot learn new material), combined with spared procedural and working memory; patients IQ and formal reasoning were fairly normal

Question 31

What is Korsakoff’s Syndrome?

Answer 31

Progressive degeneration of the mammillary bodies, hippocampal complex and dorsomedial thalamic nucleus; impedes retention of newly acquired memory; can’t take short-term to long-term memory; difficulty in understanding written material and conducting meaningful conversations; patient will confabulate, combine fragmented memories into a synthesized memory of an “event” that never occurred; caused by a thiamine deficiency, typically associated with chronic alcoholism

Question 32

What is anosmia?

Answer 32

Loss of smell due to a viral infection of the olfactory mucosa, obstruction of the nasal passages, or may be congenital; patients do NOT recover the sense of smell

Question 33

What is phantosmia?

Answer 33

Distortion in a smell experience or the perception of a smell wen no odor is present; results from a lesion of anterior/medial temporal lobe

Question 34

What is Kluver-Bucy Syndrome?

Answer 34

Bilateral temporal lobe lesions that abolish amygdaloid complex; results in visual agnosia, hyperorality, hypermetamorphosis, placidity, hyperphagia, hypersexuality

Question 35

What are the signs of an uncal herniation?

Answer 35

Dilated pupil and abnormal eye movements (CN III involvment) with double vision ipsilateral to the herniation; weakness of the extremities (CST involvement) opposite dilated pupil; as it progresses, respiration is affected, abnormal reflexes appear, and there is a potentially rapid decline