Friday, October 31, 2014

Topographic Maps in 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. 




“Topographically” mapped visual cortical areas,such as primary visual cortex map Cartesian X-­Y positions in visual space using an approximate log conformal mapping (From The Conscious Grid).


Images of concentric circles of radii between  and  around the origin under the (conformal) map . Large circles are mapped into parallel lines with increasing real parts. (Courtesy: http://functions.wolfram.com/ElementaryFunctions/Log/visualizations/4/)

The maps are not a strict isomorphic representation of XY space. Also, neurons in such maps do not stand for “pixels” of XY space.

Kohonen Maps are relevant as a first step in understanding such topographic maps.



More here on: Wikipedia

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