Hypothalamus and Limbic Systems

Question 1

Lateral zone of the hypothalamus

Answer 1

Contains the median forebrain bundle

Damage results in a decrease in feeding behavior with resultant weight loss

Question 2

Supraoptic region nuclei

Answer 2

Supraoptic/paraventricular nucleus
Suprachiasmatic nucleus
Anterior nucleus

Question 3

Supraoptic/paraventricular nucleus

Answer 3

Contain oxytocin and ADH which go to the posterior pituitary

Lesion can result in diabetes insipidus, increased H2O intake, increased urination

Question 4

Suprachiasmatic nucleus

Answer 4

Receives retinal input and is involved in circadian rhythms
Damage to this area may modify these rhythms
Gene products indirectly control melatonin secretion

Question 5

Anterior nucleus

Answer 5

Range of visceral/somatic functions

Temperature regulation

Question 6

Medial zone nuclei

Answer 6

Medial mammillary nucleus in posterior region

Ventromedial and dorsomedial nuclei in tuberal region

Question 7

Medial mammillary nucleus

Answer 7

Afferents from the hippocampus via the fornix
Efferents to thalamus and brain stem
Lesions result in an inability to process short term events into long term memory

Question 8

Ventromedial nucleus

Answer 8

Considered to be a satiety center

Lesions cause excessive eating and abnormal weight gain

Question 9

Dorsomedial nucleus

Answer 9

Subserves function of emotional behavior
Stimulation causes sham rage
Destruction results in decreased aggression and feeding

Question 10

What nuclei are served by the anterior communicating and anterior cerebral A1 arteries

Answer 10

Preoptic and supraoptic region: supraoptic/paraventricular, suprachiasmatic, anterior nuclei
Rostral part of lateral zone

Question 11

What nuclei are served by posterior communicating artery and posterior cerebral P1 segment

Answer 11

Rostral posterior communicating artery- tuberal region

Caudal posterior communicating artery- mammillary region

Question 12

Fornix

Answer 12

Afferent fibers
Arises from subiculum and hippocampus
Largest single input to the hypothalamus

Question 13

Medial forebrain bundle

Answer 13

Afferent dopaminergic fibers (part of limbic system)
Interconnects septal nuclei, hypothalamus and midbrain tegmentum
Courses through lateral hypothalamic zone

Question 14

Amygdalohypothalamic fibers

Answer 14

Afferent fibers
Stria terminalis and ventral amydalofugal pathways
Both target septal nuclei, preoptic area and medial hypothalamic zone

Question 15

Mammillary fasciculus

Answer 15

Efferent fibers
Originates in medial mammillary nucleus
Bifurcates into mammillothalamic and mammillotegmental tracts
Projects to anterior nucleus of thalamus, an important part of the circuit of papez

Question 16

Hypothalamothalamic fibers

Answer 16

Efferent fibers

From lateral preoptic area to the dorsomedial nucleus of the thalamus and amygdaloid nucleus

Question 17

Hypothalamomedullary fibers

Answer 17

Direct link to ANS

Travel to solitary nucleus, dorsal vagal motor nucleus and nucleus ambiguus

Question 18

Hypothalmospinal fibers

Answer 18

Direct link to ANS
Travel to interomediolateral cell column (GVE preganglionics)
Lesions in anterolateral medulla disrupt these fibers and disrupt sympathetic flow to the face (horners syndrome) and the body

Question 19

Posterior longitudinal fasciculus and mammillotegmental tract

Answer 19

Indirect link to ANS
Both target the PAG
PAG will target other visceral areas of the brainstem and influence autonomic nuclei there

Question 20

Hippocampal formation

Answer 20

Includes hippocampus, subiculum, entorhinal cortex and dentate gyrus
CA1, CA2, CA3, CA4

Question 21

Afferent pathway of hippocampal formation

Answer 21

Dentate gyrus –> CA3 —> CA1 –> Subiculum

Question 22

Efferent pathway of hippocampal formation

Answer 22

Subiculum–>Fornix

Terminates in medial mammillary nucleus, ventromedial nucleus and anterior nucleus of thalamus

Question 23

Cingulate gyrus

Answer 23

Afferents from thalamus and cortex

Projects to entorhinal cortex via the cingulum

Question 24

Amygdala afferents

Answer 24

Afferents from inferior temporal association cortex, thalamus, septum and olfactory tract, brainstem

Question 25

Amygdala efferents

Answer 25

Stria terminalis- outputs to the hypothalamus and basal ganglia to permit motor behavioral responses Ventral amydalofugal pathway- Major efferent fiber bundle with two general trajectories: Hypothalamus/septal nuclei, frontal/prefrontal cortex, cingulate and insular cortices Brainstem to terminate in visceral (dorsal motor vagal) and raphe nuclei

Question 26

Papez circuit

Answer 26

Simplification of the role of limbic system in modulating feelings Cingulate gyrus projects--> hippocampal formation (subiculum and entorhinal cortex) Hippocampus--> fornix--> medial mammillary nucleus Medial mammillary nucleus--> anterior nucleus of thalamus (via mammillothalamic tract) Anterior nucleus--> cingulate gyrus

Question 27

Septal region

Answer 27

Limbic structure thought to help control rage behavior

Question 28

Nucleus accumbens

Answer 28

Receives input from amygdala and hippocampus Important role in behaviors related to addiction and chronic pain Efferents include hypothalamus, brainstem and globus pallidus

Question 29

VTA ventral tegmental area

Answer 29

Large number of dopaminergic neurons Form connections with ventral striatum, amygdala, and other limbic structures Efferents to nucleus accumbens plays important role in reward and motivation, may contribute to addiction

Question 30

Hippocampal amnesia

Answer 30

Bilateral hippocampal lesions Deficit in anterograde episodic memory, but spared procedural and working memory I.Q. and formal reasoning remain about normal

Question 31

Korsakoffs syndrome

Answer 31

Progressive degeneration of mammillary bodies, hippocampal complex and dorsomedial thalamic nucleus Impedes retention of new memories - Short term cannot go long term Difficulty learning new tasks Difficulty understanding written material or conducting meaningful conversations Patients combine fragmented memories into a new memory that never occurred Caused by thiamine deficiency associated with chronic alcoholism

Question 32

Phantosmia

Answer 32

Olfactory hallucination Distortion in a smell experience or the perception of a smell when no odor is present Lesion of anterior/medial temporal lobe can cause this Or lesion of hippocampus, amygdala or medial dorsal thalamic nuclei

Question 33

Kluver Bucy syndrome

Answer 33

Bilateral temporal lobe lesions that abolish amygdaloid complex Visual agnosia - cannot recognize objects Hyperorality- tendency to examine objects by mouth Hypermetamorphosis- compulsion to intensively explore the immediate environment or overreact to visual stimuli Placidity- may not show fear or anger even when appropriate Hyperaphagia- excessive eating even when not hungry or eating objects that aren't food Hypersexuality

Question 34

Uncal herniation

Answer 34

Dilated pupil with double vision ipsilateral to lesion Weakness of extremities contralaterally Respiration can be affected, abnormal reflexes