Modeling the Emergence of Whisker Direction Maps in Rat Barrel Cortex
A The whiskers are arranged on the snout of a 10 day old rat pup in an orderly grid pattern. B This pattern is reproduced in barrel clusters, revealed here in a tangential section in L4 barrel cortex stained for cytochrome oxidase, such that neurons in each cluster respond preferentially to stimulation of the whisker in the corresponding position in the whiskerpad. C Within a supra-barrel, a pinwheel map has been measured for the direction in which the corresponding whisker is deflected . The map is described as somatotopic because deflecting the principal whisker (PW) in the direction of an adjacent whisker on the snout selectively activates neurons in the PW's barrel that are closest to the adjacent whisker barrel. Reprinted and adapted by permission from Macmillan Publishers Ltd: Nature Neuroscience , copyright 2006; colors show the direction tuning of neurons in each location within a barrel, according to the color key in D. The black dots show positions of electrode penetrations, where multiple dots correspond to multiple-unit recordings. The white box in A outlines the base of the PW for the corresponding barrel outlined in B and whose supra-barrel is enlarged in C.