Journal of Neurophysiology, Vol 53, Issue 3 686-698, Copyright © 1985 by APS
An electrophysiological and anatomical study of projections to the mouse cortical barrelfield and its surroundings
J. C. Nussbaumer and H. Van der Loos
This study establishes a cortical map of the somatosensory periphery of the
mouse head, with emphasis on the whisker pad. Data in the literature on the
projection of the common hair follicles are confusing, notably the question
whether or not this projection is separated from or overlaps with that of
the facial vibrissae, the barrelfield. Microelectrode recordings in the
barrelfield and its immediate surroundings upon natural stimulation of the
periphery were followed by microlesions and histological reconstruction.
Results show that the barrelfield consists of two parts: an anterior part
where vibrissal follicles and the skin bearing them are represented, and a
posterior part receiving only vibrissa inputs. The skin between these
latter vibrissae is represented outside the barrelfield. We conclude that
the partially dissociated cortical representation of skin and vibrissae may
allow large vibrissae to be used in tasks requiring greater acuity than the
shorter ones provide. This hypothesis is supported by the observation that,
owing to special muscles, large vibrissae are more mobile than short ones.
We also propose that the segregation of inputs from vibrissae and common
fur is related to the number of nerve fibers serving one follicle, and we
indicate an experimental model to test this possibility.
