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23 Cards in this Set
- Front
- Back
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What is the internal medullary lamina?
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Y-shaped fiber bundle that divides the different nuclei in the thalamus
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What are intralaminar nuclei (IL)?
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Small collections of gray matter located within the internal medullary lamina
-ascending reticular activating system (lethargy, stupor, coma), motor system |
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What is the dorsal median nucleus (DM or MD)?
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Has reciprocal connections with prefrontal cortex and is important for working memory
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What does the anterior part of the ventral lateral nucleus of the thalamus do (VLa)?
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-Inputs from globus pallidus
-reciprocal connections with premotor cortex |
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What does the posterior part of the ventral lateral nucleus of the thalamus do (VLp)?
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-Inputs from globus pallidus and cerebellum
-reciprocal connections with motor cortex |
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What does the medial part of the ventral posterior nucleus of the thalamus do (VPm)?
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-receives somatosensory inputs from face (trigeminal system)
-reciprocal connections with face area of somatosensory cortex Other part (also called VM): -receives gustatory inputs -reciprocal connections with gustatory areas of cerebral corte |
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What does lateral part of ventral posterior nucleus of the thalamus do (VPl)?
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-receives somatosensory inputs from body (medial lemniscus)
-reciprocal connections with somatosensory cortex representation for body |
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What does medial geniculate body of the thalamus do (MG)?
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-located in posteromedial aspect of thalamus
-inputs from auditory system -reciprocal connection with primary auditory cortex |
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What does lateral geniculate body (LG) of thalamus do?
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-located in posterolateral aspect of thalamus
-inputs from visual system -reciprocal connections with primary visual cortex |
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What are VP and LG lesions associated with?
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Sensory dysfunction
-VP lesion will affect pain sensation to same degree as other somatosensory modalities (unlike SS cortex lesion) |
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What can lesion of VL cause?
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Contralateral ataxia due to interruption of dentatorubrothalamic feedback to motor cortex
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What can lesion of MD cause?
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Amnesia (can't form new memories for facts or events)
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What do thalamic lesions never produce?
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Weakness
-VL is not part of the descending pyramidal system |
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What is the thalamic syndrome?
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-Lesion of VP and adjacent structures
-threshold for somatosensation is increased, but once threshold is reached sensations are exaggerated, distorted, and disagreeable |
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What will happen if have lesion of medial geniculate body?
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Nothing if only on one side because auditory system is bilateral
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What are the two types of neurons found in the cerebral cortex?
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Granule or stellate neurons: input cells and interneurons (many dendrites and a short axon)
Pyramidal neurons: projection or output neurons (big dendrites, long axon) |
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What is a cortical column?
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The functional unit of cortical activity
-extends from base of cerebral cortex to pia -neurons in column are interconnected and related to same receptive field |
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Where do the inputs to the column come from?
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1. Specific thalamic projections from thalamic nucleus
2. Nonspecific thalamic afferents from intralaminar thalamic nuclei (related to arousal) 3. Association fibers from other cortical columns in same cerebral hemisphere 4. Commissural fibers from cortical columns of contralateral cerebral hemisphere |
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Where do the the outputs from the column go?
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1. Projection fibers extend to deep gray-matter structures, brain stem, or spinal cord
2. Association fibers project to cortical columns located in same hemisphere 3. Commissural fibers project to cortical columns in contralateral cerebral hemisphere |
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What are the layers roles in input/output function of the column?
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1-4 are generally input centers (4 is the primary input center for the column
3-6 are generally output centers (5 is the primary output center for the column) --Clearly there is overlap between input/output layers |
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What is the general principle of cytoarchitetectonics?
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Different areas of cerebral cortex have different jobs so look different under the microscope (have different types of cells)
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What are the three cytoarchitectonic types?
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1. Consists almost entirely of pyramidal (output) cells; has very prominent layers III, V, and VI (internal/external pyramidal, multiform); corresponds primarily to primary and pre-motor cortex
2. Consists almost entirely of granule/stellate input cells; very prominent layers II and IV (external/internal granule); corresponds to primary somatosensory, auditory, visual cortices 3. Six visible layers (corresponds to association cortex) |
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What can thalamic lesions lead to?
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Contralateral somatosensory loss, homonymous hemianopia, hemiataxia, deficits of higher cortical function, contralateral "thalamic pain syndrome"
-Bilateral thalamic lesions can lead to supor and coma |
