Fig. 1. Demonstration of crayfish sensory–motor LTP.A, Drawing of in vitro preparation.G3, G4, and G5, Third, fourth, and fifth thoracic ganglia; Pro,Rem, Lev, Dep, motor nerves innervating promotor, remotor, levator, and depressor muscles, respectively; CBn, sensory nerve innervating the coxo-basipodite chordotonal organ (CBCO). Single or paired intracellular recordings (ME1 andME2) were made from a motor neuron (MN) and CBCO sensory terminal (CBT) within the fifth ganglion (see detail inright inset). B, Paired recordings of a CBT and MN were used to analyze the unitary monosynaptic EPSP produced in the MN in response to a CBT spike before (control) and after (postinduction) intracellular 10 Hz stimulation of the recorded MN (induction). After induction, the EPSP amplitude was increased dramatically. See superimposed raw data traces (top) and an average from 25 traces (middle). C, Time course of the mean amplitude of unitary EPSPs before and after MN intracellular stimulation (vertical gray bar), represented as a percentage of control (left) and maximum (right) values. Data were pooled from three representative experiments.