Neuro Exam 3: Limbic System

Front 1

What forms the lower walls and floor of the third ventricle?

Back 1

Hypothalamus
-below the hypothalamic sulci
-limited anteriorly by the optic chiasm and caudally by the midbrain

Front 2

What is the functions of the hypothalamus?

Back 2

Maintain internal homeostasis by managing endocrine and autonomic nervous systems
-important role in regulation of food/water and circadian rhythms

Front 3

What are the three main regions of the hypothalamus?

Back 3

1. Supraoptic (anterior): contains the paraventricular nucleus, supraoptic nucleus, suprachiasmatic nucleus
2. Tuberal (medial) region: ventromedial, dorsomedial, posterior hypothalamic nuclei, tuberal nuclei
3. Mammillary (posterior) region: contains the mammillary bodies, which are part of the limbic system;

Front 4

Where do the axons from the supraoptic and paraventricular nuclei go?

Back 4

Pass through the stalk of the pituitary and terminate in its posterior lobe in juxtaposition with blood vessels
-there they release antidiuretic hormone (ADH aka vasopressin) and oxytocin which diffuse into the blood to reach their appropriate target organs

Front 5

What does the suprachiasmatic nucleus do?

Back 5

Entrains certain body rhythms to the 24 hour light-dark cycle
-melatonin receptors in the suprachiasmatic nucleus (MT1 involved in promotion of sleep; MT2 involved in maintenance of circadian rhythm)

Front 6

What do the tuberal region nuclei do?

Back 6

Project on the median eminence. They synthesize, transport, and release peptides into veins that connect the hypothalamus with the anterior pituitary
-these substances, called hypothalamic releasing factors, regulate the function of the anterior pituitary trophic hormones
-others related to ANS function, temp. regulation, feeding/satiety, thirst, sexual behaviors

Front 7

What are the most important afferent connections of the hypothalamus?

Back 7

-Fornix: contains connections from hippocampus that project mainly to mammillary body
-Corticohypothalamic fibers from frontal lobe (orbitofrontal cortex)

Front 8

What is the main efferent outflow of the hypothalamus?

Back 8

-Mammillothalamic tract projects to anterior nucleus of the thalamus

Front 9

What is the pineal organ?

Back 9

Connected to the diencephalon by a short stalk and projects back over the colliculi
-produces melatonin, which is synthesized from serotonin and secreted into the blood and CSF
-Melatonin synthesis and secretion are increased during dark periods and maintained at low level during daylight hours

Front 10

What is the limbic system?

Back 10

A heterogeneous collection of interrelated structures involved in homeostasis, eating, sleeping, sexual behavior, affective states, neuroendocrine control, motivation, memory, and species-specific behaviors
-Limbic lobe: subcallosal gyrus, cingulate gyrus, and hippoocampal formation
-Limbic system: Limbic lobe, parts of hypothalamus, septal area, part of amygdala, nucleus accumbens, neocortical areas such as orbitofrontal cortex

Front 11

What is the hippocampal formation?

Back 11

Parahippocampal gyrus (inferomedial temporal lobe), subiculum (more superiorly than PH), hippocampus (lateral to subiculum), dentate gyrus (where hippocampus ends) (all connected)
-are cerebral cortex although simpler cytoarchitecture than neocortex
-Best seen in coronal section through the MTL

Front 12

What is the term for the anterior portion of the parahippocampal gyrus?

Back 12

entorhinal cortex

Front 13

What part does CA1 of the hippocampus border on?

Back 13

subiculum

Front 14

What part does CA4 of the hippocampus border on?

Back 14

dentate gyrus

Front 15

What is the primary functional circuit within the hippocampal formation?

Back 15

-entorhinal cortex
-dentate gyrus
-CA3 of hippocampus
-CA1 of hippocampus
-subiculum
-entorhinal cortex

Front 16

Where does AD typically start?

Back 16

entorhinal cortex

Front 17

Which area is particularly affected by ischemia (not enough blood flow)?

Back 17

CA1 of the hippocampus

Front 18

Each hippocampal formation also has a strong reciprocal projection to this via the ipsilateral fornix

Back 18

ipsilateral mammillary body

Front 19

What do the reciprocal connections between the entorhinal cortex and the cerebral neocortex do?

Back 19

Cause new memories to be laid down in cerebral neocortex

Front 20

What is the septal area?

Back 20

Mass of nuclei forming a major portion of the medial wall of he hemisphere, dorsal to the anterior commissure and anterior to the fornix
-related to hippocampus and hypothalamus
-lies closely adjacent to heads of caudate nuclei on either side

Front 21

What is the amygdala?

Back 21

Large nuclear mass at tip of temporal horn of lateral ventricle; continous medially with cortex of uncus
-divided into basolateral (part of limbic system) and corticomedial (part of olfactory system)
-amygdala plays role in emotion and species-specific behaviors (mediating emotions)

Front 22

What areas regulate rewards?

Back 22

Nucleus accumbens and septal nuclei
-Dopamine from VTA to NA and septal nuclei involved in rewards and drug abuse

Front 23

What is Kluver Bucy syndrome?

Back 23

-Bilateral anterior temporal lobe lesions
-combination of over eating, placidity, poor visual recognition, compulsive examination of objects, hypersexual, hyperorality