Hypothalamus, Thalamus, and Limbic System Flashcards
General function of thalamic nuclei
Relay general and special sensory info
Receive inputs from cerebellum and basal ganglia
Relay to associative and limbic cortical areas
The majority of the functional thalamic nuclei project to the ____ cerebral cortex
Ipsilateral
Thalamic nuclei associated with lateral nuclear group
Ventral anterior Ventral lateral VPM/VPL LGN MGN
Thalamic nuclei associated with the anterior, medial, and intralaminar groups are non-specific and largely project to the broad ____ and _____ areas
Limbic; hypothalamic
Function of anterior, medial, and intralaminar nuclear groups
Instinctive drives, mood, emotional behavior
Among the anterior, medial, and intralaminar thalamic nuclear groups, the lateral dorsal nucleus is part of the ____ system
Limbic
Ventral anterior nuclei (of lateral thalamic nuclear group) project where?
Basal ganglia and primary/supplementary motor areas
Ventral lateral nuclei (of lateral thalamic nuclear group) project where?
Basal ganglia
Cerebellum
Primary/supplementary motor areas
VPM/VPL nuclei (of lateral thalamic nuclear group) project where?
Spinothalamic tracts
Medial lemniscus
Trigeminothalamic tracts
Functions of LGN vs. MGN nuclei (of lateral thalamic nuclear group)
LGN = visual afferents
MGN = auditory afferents
The reticular formation is made up of reticular nuclei which are diffuse and ill-defined. where are they located?
Brainstem — at midbrain, pons, and medullary levels
Type of serotonergic reticular nucleus that makes up a series of midline nuclei extending through the length of the brainstem
Raphe nuclei
Raphe nuclei have ascending projections to what brain structures?
Thalamus Hypothalamus Striatum Amygdala Hippocampus Widespread cerebral cortex
Raphe nuclei are believed to be involved in what type of function?
Mood + cognitive function
Neural mechanisms of sleep
Function of reticular activating system
Controls states of consciousness, sleep, REM, HR, and respirations
Reticular nuclei re interconnected with basal nuclei and motor systems in the brainstem with widespread afferents and efferent connections with other parts of CNS.
Descending reticulospinal tracts originate from the _____ and _____ RAS and influence ___________
Medullary; pontine
Muscle tone and posture
Ascending fibers from RAS are cholinergic and receive direct or indirect input from multiple sensory sources
They serve as an intermediary of _____ nuclei (mostly intralaminar) and influence activation of ______ ____ and heightened arousal
Thalamic; cerebral cortex
Stria terminalis serves as efferent projections of the _______ in the brain, running in the walls of the lateral ventricle and following the curvature of the _____ nucleus to the hypothalamus and basal ganglia
Amygdala; caudate
Ventral amygdalo-fugal fibers serve as efferent projections of the amygdala. Axons primarily from the basolateral cells synapse in the______ and _____ nuclei, as well as frontal, prefrontal, cingulate, insular, and inferior temporal cortices
Hypothalamus; septal
Ventral amygdalo-fugal fibers from the central nucleus descend into the brainstem to terminate in the ______ and _____ nuclei, among others
Visceral (dorsal motor vagal); raphe
What is the papez circuit?
Cingulate gyrus —> hippocampal formation and entorhinal areas
Hippocampus —> mammillary nuclei
Medial mammillary nucleus —> anterior nucleus of thalamus —> cingulate gyrus
[overall it is a pathway originating from cingulate gyrus exerting cortical conrol of emotional activity]
The papez circuit is completed by the following connections:
________ tract that connects the medial mammillary nucleus to the anterior nucleus of the thalamus
Thalamocortical fibers from the _____ nucleus to cortex of cingulate gyrus
Projection from cingulate cortex to _____ cortex, subiculum, and hippocampus
The _______ (via fornix) returns info to mammillary body
Mammillothalamic
Anterior
Entorhinal
Subiculum
Neuroanatomical basis and clinical manifestation of anosmia
Loss of smell d/t viral infection of olfactory mucosa, obstruction of nasal passages, or congenital defect
Lesions occur d/t shearing of CN I to tumors in floor of anterior cranial fossa
What is phantosmia
Olfactory hallucinations = distortion in smell experience or perception of a smell when no odor is present
[due to abnormal sequence of neuronal activity]
Lesions in what brain areas may result in phantosmia?
Anterior/medial temporal lobe
Hippocampus
Amygdala
Medial dorsal thalamic nuclei
What causes hippocampal amnesia? What is the result?
Bilateral lesions of hippocampi
Profound deficit in anterograde episodic memory (cant learn new material)
[however still maintain procedural and working memory, as well as IQ and formal reasoning]
Korsakoff’s results from progressive damage to what brain areas?
Mammillary bodies
Hippocampal complex
Dorsomedial thalamic nucleus
Symptoms of korsakoff’s syndrome
Impedes retention of newly acquired memory
Difficulty learning new tasks
Difficulty understanding written material and conducting meaningful conversation
Pt will confabulate — combine fragmented memories into synthesized memory of event that never occurred
[caused by thiamine deficiency associated with chronic alcoholism]
Cause and symptoms of Kluver-Bucy syndrome
Caused by bilateral temporal lobe lesions that abolish amygdaloid complex
Results in behavioral changes including: Visual agnosia Hyperorality Hypermetamorphosis Placidity Hyperphagia Hypersexuality
What is an uncal herniation?
Uncus (and possibly parahippocampal gyrus) moves down over edge of tentorium cerebelli d/t hemorrhagic lesion or tumor in hemisphere
Initially compresses midbrain, may extend into lower brainstem levels
Signs of uncal herniation
Dilated pupil and abnormal eye movements (CN III) with double vision ipsilateral to herniation
Weakness of extremities (CST involvement) opposite dilated pupil
As it progresses, respiration is affected, abnormal reflexes appear, potentially rapid decline
