Hypothalamus, Thalamus, And Limbic System Flashcards
The thalamus consists of numerous nuclei with connections to the cerebral cortex. What is their fx?
Relay general and special sensory info
Receive inputs from the cerebellum and basal ganglia
Relay to associative and limbic cortical areas
What are the five types of lateral thalamic nuclei?
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
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?
Non-specific
Broad limbic and hypothalamic areas
Lateral dorsal nucleus: part of limbic system; instinctive drives, mood, emotional behavior
The reticular activating system contains the ___ and are located in the _____.
RAS controls ____ and is interconnected with the ____ and ____ in the brainstem.
Reticular nuclei; brainstem including the midbrain, pons, and medulla
States of consciousness, sleep, REM, HR, respiration; basal nuclei and motor centers
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.
Medullary and pontine RAS; muscle tone and posture
Multiple sensory sources; thalamic nuclei (intralaminar nuclei)
The ____ are a series of midline nuclei that extend throughout the length of the brainstem.
They are ____.
They send ascending projections where?
Fx?
Raphe nuclei
Thalamus, hypothalamus, striatum, amygdaloid, hippocampus, and cerebral cortex
Mood and cognitive fx and neural mechanisms of sleep
The _____ is a small region of the diencephalon that is separated superiorly from the dorsal thalamus by the ____.
Fx?
Hypothalamus; hypothalamic sulcus
Control of visceral fx and emotional behavior and temp control
What are the four divisions of the hypothalamus?
Preoptic area
Periventricular zone
Medial zone
Lateral zone
The preoptic area of the hypothalamus is located where?
What does it contain?
What is the fx of the medial preoptic nucleus?
Extends rostrally and forms a continuation with the basal forebrain
Medial and lateral preoptic nuclei
Contains neurons that make GnRH
The periventricular zone of the hypothalamus is located where?
Fx?
Adjacent to the 3rd ventricle
Synthesizes releasing hormones, projects via hypophyseal portal system to anterior pituitary
The medial zone of the hypothalamus is divided into what three regions with their corresponding nuclei?
Supraoptic (chiasmatic) region
Tuberal region
Mammillary region
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.
Medial forebrain bundle
RAS
Lateral hypothalamic nucleus
The main hypothalamic afferent fibers come from the ____.
This arises from the neurons in the ____ and _____.
It is divided into what two bundle?
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
The ____ is another hypothalamic afferent fiber and contains fibers that course rostrocaudally through the lateral hypothalamic zone.
Its ascending and descending fibers interconnect what?
Medial forebrain bundle
Septal nuclei, hypothalamus, midbrain tegmentum
_____ is the progressive degeneration of the mammillary bodies, hippocampal complex, and dorsomedial thalamic nucleus.
What are the symptoms?
Cause?
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
What is the limbic system?
What gives inputs to the limbic system?
Connections that provide the fundamental basis for instinctive and emotional aspects of behavior and memory
Amygdala
What is the fx of the amygdala?
Location?
What are the afferent inputs to the amygdala?
What are efferent outputs from the amygdala?
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
What is the sepal region location and fx?
Small area rostral to the anterior commissure and in the medial wall of the hemisphere; control of rage behavior
What is the medial forebrain bundle location and a fx?
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
What is the location and fx of the nucleus accumbens?
Efferent fibers?
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
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?
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)
What are the four layers of the dentate gyrus and the hippocampus from external to innermost?
What is the fornix?
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
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.
Perforant pathway
Molecular layer
Molecular layer; CA3 region
CA1 region
Fornix
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 ____.
Subiculum; pyramidal cells
Fornix
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?
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
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
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
The initial segment of the Papez circuit is from the ___ to the ____.
What are the connections of the Papez circuit?
Subiculum; medial mammillary nucleus (postcommissural fornix)
- Mammillothalamic tract connects -> medial mammillary nucleus to the anterior nucleus of the thalamus
- Anterior nucleus -> thalamocortical fibers -> cortex of cingulate gyrus
- Projection from cingulate gyrus -> entorhinal cortex, subiculum, and hippocampus
- Subiculum -> returns info (via fornix) ->to the mammillary body
What is hippocampal amnesia?
What does it cause?
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
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 ____.
Continuous around the splenium of the corpus callosum
Parahippocampal gyrus via the fibers of the cingulum
Papez circuit
Kluver-Bucy syndrome is a ___ lesion that abolishes the ____.
What six behavior changes does it cause?
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
