The Journal of Neuroscience, March 29, 2006, ():
A 3-Synapse Positive Feedback Loop Regulates the Excitability of an Interneuron Critical for Sensitization in the Leech
J. Neurosci. Crisp and Muller
26: 3524
Supplemental data
Files in this Data Supplement:
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Supplemental Figure 1. Simplified diagram of circuitry underlying the shortening reflex, and its sensitization, in the leech. Subscripts indicate the numbers of each type of cell present within a single ganglion. White circles indicate cells in adjacent ganglia. The touch-sensitive (T), pressure-sensitive (P) and nociceptive (N) mechanoreceptors, which have their nerve endings in the skin, feed excitatory synaptic input onto the longitudinal (L) motor neurons; contraction of the longitudinal muscle shortens the leech. The T and P cells also excite the S and coupling (C) interneurons, which are strongly electrically coupled. The yet unidentified shortening interneurons (SHI) play an important role in shortening, but their inputs are not known. The S cell feeds additional excitatory synaptic input onto the L motoneuron, increasing the strength of the shortening muscle contraction after sensitization. Serotonin, secreted by the Retzius (R) cells, enhance S cell excitability, presumably acting in a paracrine manner. S cell impulse activity excites the Retzius cells through a polysynaptic connection in which the C cells are the interneurons. Straight arrows indicate the direction of information flow; the circular arrow denotes the positive feedback loop formed by the S, C and Retzius cells. Asterisks indicate connections studied in this report. This figure has been adapted from Duan et al. (2005).
