Hypothalamus, Thalamus, And Limbic System

Question 1

The thalamus consists of numerous nuclei with connections to the cerebral cortex. What is their fx?

Answer 1

Relay general and special sensory info

Receive inputs from the cerebellum and basal ganglia

Relay to associative and limbic cortical areas

Question 2

What are the five types of lateral thalamic nuclei?

Answer 2

Ventral anterior: basal ganglia and primary/supplementary motor areas

Ventral lateral: basal ganglia, cerebellum, and primary/supplementary motor areas

VPM/VPL: spinothalamic tracts and medial lemniscus, trigeminothalamic tracts

LGN: visual afferents

MGN: auditory afferents

Question 3

The anterior and medial nuclear groups and intralaminar groups are ___ nuclei.

They project to the ____ and ____ areas and include the ____ nucleus.

What is the fx of this nucleus?

Answer 3

Non-specific

Broad limbic and hypothalamic areas

Lateral dorsal nucleus: part of limbic system; instinctive drives, mood, emotional behavior

Question 4

The reticular activating system contains the ___ and are located in the _____.

RAS controls ____ and is interconnected with the ____ and ____ in the brainstem.

Answer 4

Reticular nuclei; brainstem including the midbrain, pons, and medulla

States of consciousness, sleep, REM, HR, respiration; basal nuclei and motor centers

Question 5

RAS contains descending reticulospinal tracts originate in the ____ and influence _____.

RAS ascending fibers (cholinergic) receive direct or indirect input from ____. They send their information to the _____ causing activation of the cerebral cortex and increase arousal.

Answer 5

Medullary and pontine RAS; muscle tone and posture

Multiple sensory sources; thalamic nuclei (intralaminar nuclei)

Question 6

The ____ are a series of midline nuclei that extend throughout the length of the brainstem.

They are ____.

They send ascending projections where?

Fx?

Answer 6

Raphe nuclei

Thalamus, hypothalamus, striatum, amygdaloid, hippocampus, and cerebral cortex

Mood and cognitive fx and neural mechanisms of sleep

Question 7

The _____ is a small region of the diencephalon that is separated superiorly from the dorsal thalamus by the ____.

Fx?

Answer 7

Hypothalamus; hypothalamic sulcus

Control of visceral fx and emotional behavior and temp control

Question 8

What are the four divisions of the hypothalamus?

Answer 8

Preoptic area

Periventricular zone

Medial zone

Lateral zone

Question 9

The preoptic area of the hypothalamus is located where?

What does it contain?

What is the fx of the medial preoptic nucleus?

Answer 9

Extends rostrally and forms a continuation with the basal forebrain

Medial and lateral preoptic nuclei

Contains neurons that make GnRH

Question 10

The periventricular zone of the hypothalamus is located where?

Fx?

Answer 10

Adjacent to the 3rd ventricle

Synthesizes releasing hormones, projects via hypophyseal portal system to anterior pituitary

Question 11

The medial zone of the hypothalamus is divided into what three regions with their corresponding nuclei?

Answer 11

Supraoptic (chiasmatic) region

Tuberal region

Mammillary region

Question 12

The lateral zone of the hypothalamus contains the ____.

It interconnects the lateral zone with the septal nuclei and brainstem _____.

The ____ is a large cell group that fx as the feeding center.

Answer 12

Medial forebrain bundle

RAS

Lateral hypothalamic nucleus

Question 13

The main hypothalamic afferent fibers come from the ____.

This arises from the neurons in the ____ and _____.

It is divided into what two bundle?

Answer 13

Fornix

Subiculum and hippocampus

Precommissural bundle (hippocampus): passes to septal and preoptic nuclei and to the anterior hypothalamic region

Postcommissural bundle (subiculum): projects to the medial mammillary nucleus with lesser inputs to the anterior thalamic nucleus and lateral hypothalamus

Question 14

The ____ is another hypothalamic afferent fiber and contains fibers that course rostrocaudally through the lateral hypothalamic zone.

Its ascending and descending fibers interconnect what?

Answer 14

Medial forebrain bundle

Septal nuclei, hypothalamus, midbrain tegmentum

Question 15

_____ is the progressive degeneration of the mammillary bodies, hippocampal complex, and dorsomedial thalamic nucleus.

What are the symptoms?

Cause?

Answer 15

Korsakoff’s syndrome

Impedes the retention of new memory (short term memory not converted to long term)

Pts can’t learn new tasks, understand written material, and have conversations

Pts confabulate: combine fragmented memories together

Chronic EtOH, thiamine deficiency

Question 16

What is the limbic system?

What gives inputs to the limbic system?

Answer 16

Connections that provide the fundamental basis for instinctive and emotional aspects of behavior and memory

Amygdala

Question 17

What is the fx of the amygdala?

Location?

What are the afferent inputs to the amygdala?

What are efferent outputs from the amygdala?

Answer 17

Vital to the motivational and emotional connotations of an experience

Near temporal pole, between inferior horn of the lateral ventricle and lentiform complex

Afferents to the inferior temporal association cortex, thalamus, septum, olfactory tract, projections from the brainstem via the medial forebrain bundle

Efferents from the ventral amygdalofugal pathway, stria terminalis, stria medullaris thalami

Question 18

What is the sepal region location and fx?

Answer 18

Small area rostral to the anterior commissure and in the medial wall of the hemisphere; control of rage behavior

Question 19

What is the medial forebrain bundle location and a fx?

Answer 19

Group of fibers that course rostrocaudally through the lateral hypothalamic area

Conveys ascending inputs into the hypothalamus and into the septal region

Allows septal nuclei and hypothalamus to communicate with the brainstem

Contain dopamine containing fiber that are related to perceptions of pleasure or drive reduction

Question 20

What is the location and fx of the nucleus accumbens?

Efferent fibers?

Answer 20

Located in the rostral and ventral forebrain, where the head of the caudate nucleus and putamen are continuous

Receives input from the amygdaloid complex, hippocampal formation, and amygdalofugal fibers

Role in behaviors related to addiction and chronic pain

Efferents include fibers to the hypothalamus, nuclei of the brainstem, and globus pallidus

Question 21

What are the three parts of the hippocampus?

The medial edge of the hippocampal formation is formed by the ____ and the ____.

What is the subiculum?

Answer 21

Subiculum, hippocampus proper, and dentate gyrus

Dentate gyrus and fimbria of the hippocampus

Transitional area between the three-layered hippocampus and five-layered entorhinal cortex (parahippocampal gyrus)

Question 22

What are the four layers of the dentate gyrus and the hippocampus from external to innermost?

What is the fornix?

Answer 22

Molecular layer: afferent axons and dendrites of cells intrinsic to each structure

Granule cell layer and pyramidal layer: efferent neurons, contains granule cells/pyramidal cells, dendrites radiating into the molecular layer

Polymorphic layer: axons of pyramidal/granule cells, intrinsic neurons, glia, dendrites of neurons in the pyramidal layer (double pyramidal cells)

Innermost layer of the hippocampus: myelinated axons from cell bodies in the subiculum and hippocampus, alveus -> continuous with fimbria -> become the fornix

Fornix is the largest source of input from the hippocampus to the thalamus

Question 23

The major afferent input to the hippocampus is from cells of the entorhinal cortex via the ____ pathway.

These afferent fibers terminate in the ____ layer of the dentate gyrus, subiculum, and hippocampus.

Granule cells in the dentate gyrus project to the ____ of the ____ region of the hippocampus.

CA3 projects to ____ of the hippocampus and then to the subiculum.

The _____ conveys projections to the hippocampal formation and entorhinal cortex.

Answer 23

Perforant pathway

Molecular layer

Molecular layer; CA3 region

CA1 region

Fornix

Question 24

The efferent fibers from the hippocampus originate from cells of the ____ and ____ cells of the hippocampus.

Axons from these neurons enter the alveus, coalesce to form the fimbria, then continue as the ____.

Answer 24

Subiculum; pyramidal cells

Fornix

Question 25

The fornix is the major output of the hippocampus. It extends fibers across the midline in the _____.

Fibers originating in the subiculum form the _____. And terminate in the ____, ventromedial nucleus of the hypothalamus, and anterior nucleus of the dorsal thalamus.

The precommissural fornix is made of fibers arising in the ____. It distributes fibers to what?

Answer 25

Hippocampal decussation

Postcommissural fornix; medial mammillary nucleus

Hippocampus; septal nuclei, medial areas of the frontal cortex, preoptic and anterior nuclei of the hypothalamus , and nucleus accumbens

Question 26

Emotion mediated through the hypothalamus is controlled and modulated by fibers from the ___.

Cortical control of emotional activity is from a pathway originating from the ____ which is part of the ____.

Where do each of these project:
Cingulate gyrus
Hippocampus 
Medial mammillary nucleus
Anterior nucleus

Answer 26

Fornix

Cingulate gyrus; Papez circuit

Cingulate gyrus -> hippocampal formation and entorhinal cortex

Hippocampus -> mammillary nuclei

Medial mammillary nucleus -> anterior nucleus of the thalamus

Anterior nucleus -> cingulate gyrus

Question 27

The initial segment of the Papez circuit is from the ___ to the ____.

What are the connections of the Papez circuit?

Answer 27

Subiculum; medial mammillary nucleus (postcommissural fornix)

1. Mammillothalamic tract connects -> medial mammillary nucleus to the anterior nucleus of the thalamus
2. Anterior nucleus -> thalamocortical fibers -> cortex of cingulate gyrus
3. Projection from cingulate gyrus -> entorhinal cortex, subiculum, and hippocampus
4. Subiculum -> returns info (via fornix) ->to the mammillary body

Question 28

What is hippocampal amnesia?

What does it cause?

Answer 28

Bilateral lesions of the hippocampi

Deficit in anterograde episodic memory (cant learn new material), with spared procedural and working memory (task oriented)

IQ and formal reasoning normal

Question 29

Where is the cingulate gyrus and parahippocampal gyrus located?

What does it project to?

The principal structures of the limbic system are thus linked by a series of connections called the ____.

Answer 29

Continuous around the splenium of the corpus callosum

Parahippocampal gyrus via the fibers of the cingulum

Papez circuit

Question 30

Kluver-Bucy syndrome is a ___ lesion that abolishes the ____.

What six behavior changes does it cause?

Answer 30

Bilateral temporal lobe lesion; amygdaloid complex

Visual agnosia: inability to recognize and object by sight

Hyperorality: tendency to examine objects by mouth

Hypermetamorphosis: compulsion to explore the immediate environment or overreact to visual stimuli

Placidity: doesn’t show fear or anger even when it is appropriate

Hyperphagia: eating excessive amounts even when not hungry or when objects are not actually food

Hypersexuality: suggestive behavior and talk with vague or ill-conceived attempts at sexual contact