Dendritic sprouting and compensatory synaptogenesis in an identified interneuron follow auditory deprivation in a cricket.

We examined the effect of chronic afferent deprivation on an identified interneuron (Int-1) in the auditory system of the Australian field cricket Teleogryllus oceanicus. In normal intact crickets, the auditory afferents from each ear terminate ipsilaterally onto a single Int-1. Each bilaterally paired Int-1 is excited by ultrasound stimulation of its ipsilateral ear but not by the contralateral ear. Unilateral removal of an ear early in postembryonic development deprives the developing Int-1 of ipsilateral auditory innervation. Consequently, the ipsilateral dendrites of the deprived interneuron sprout, grow aberrantly across the ganglionic midline, and terminate specifically in the intact auditory neuropile of the contralateral (unlesioned) side, where they form functional synapses with the contralateral afferents. This unusual compensatory dendritic sprouting restores auditory function to the neuron. Thus, it is demonstrated that the dendritic shape of an identified Int, as well as its synaptic connectivity, is altered as a consequence of chronic sensory deprivation.