- Topographic map (Neuroanatomy)
A topographic map is the ordered projection of a sensory surface, like the retina or the skin, or an effector system, like the musculature, to one or more structures of the
central nervous system . Topographic maps can be found in all sensory systems and in many motor systems.Visual system
The
retina projects in an orderly fashion to thelateral geniculate nucleus of thethalamus and from there to the primaryvisual cortex ; adjacent spots on the retina are represented by adjacent neurons in thelateral geniculate nucleus and the primaryvisual cortex . This projection pattern has been termedretinotopy .Auditory system
The
organ of Corti projects in an orderly fashion to structures in thebrainstem (namely, thecochlear nuclei and theinferior colliculus ), and from there to thethalamus and the primaryauditory cortex ; adjacent sites on theorgan of Corti , which are themselves selective for thesound frequency, are represented by adjacent neurons in the aforementioned CNS structures. This projection pattern has been termedtonotopy .omatosensory system
The
cutaneous receptors of the skin project in an orderly fashion to thespinal cord , and from there, via different efferent pathways (dorsal column-medial lemniscus tract andspinothalamic tract ), to thethalamus and the primary somatosensory cortex. Again, adjacent areas on the skin are represented by adjacent neurons in all aforementioned structures. This projection pattern has been termedsomatotopy .References
* Kandel ER, Schwartz JH, Jessell TM 2000. "Principles of Neural Science, 4th ed." McGraw-Hill, New York. ISBN 0-8385-7701-6
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