About the Cover
Cover picture: Primary afferent neurons traditionally are
assumed to constitute independent sensory communication channels
leading from peripheral tissue (skin, muscle, etc.) to the CNS. Within
the nerve, they are isolated from one another by processes of Schwann
cells, as illustrated in this freeze-fracture image of a myelinated
axon in the rat sciatic nerve. Note the longitudinal seam that
represents the final loop of Schwann cell circumnavigation of the axon.
The somata of the afferent neurons in the segmental dorsal root ganglia
(DRGs) are also separated from one another, here by laminar processes
of satellite glia. Amir and Devor in this issue (pp. 4733-4741) show
that despite this structural insulation, a great majority of afferent
neurons in fact communicate with one another by means of subthreshold
graded membrane depolarizations. This cross-excitation appears to be
mediated, at least in part, by nonsynaptic release of a
neurotransmitter. This image was produced by M. Devor, with the help of
M. Ellisman.
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Copyright © 2003 by Society for Neuroscience.
