Contribution of neurons to habituation to mechanical stimulation in Caenorhabditis elegans

In Caenorhabditis elegans, a light touch induces a locomotor response. Repe ated touches, however, result in an attenuation of response, that is, habit uation. Withdrawal responses elicited by anterior touch are controlled by a nterior mechanosensory neurons (AVM and ALMs), and by four pairs of interne urons (AVA, AVB, AVD, and PVC) (Chalfie et al., 1985; White et al., 1986). To identify the neurons that participate in habituation, we ablated these n eurons with laser microbeam and investigated the resulting habituation of t he operated animals. The animals lacking both left and right homologues AVD LR were habituated more rapidly than intact animals. We propose that chemic al synapses at AVD play a critical role in the habituation of intact animal s. (C) 2000 John Wiley & Sons, Inc.