Lateral inhibition mediated by a non-spiking interneuron: circuit properties and consequences for behavior.

The terminal abdominal ganglion of the crayfish contains about 650 cells, approximately 1/2 of which are local. In the mechanosensory system, an identified, non-spiking local interneuron mediates lateral inhibition (across the midline) of a highly restricted set of projecting sensory interneurons. Our evidence suggests that this neuron is the exclusive pathway for the form of lateral inhibition that we studied. The 'precurrent' mode of inhibition found in this system causes responses to stimuli that are common to both sides to be attenuated, and conversely will enhance the difference signal produced by partially lateralized input.