Figure 5.

Haltere stimulation entrains spike timing in some CX units. A, Raster plot of spike times in response to a 20 Hz sine wave oscillation of the haltere. The first spike of each stimulation cycle is labeled in red; subsequent spikes are black. B, Example of a unit with phase locking in two trials that occurred 3.64 min apart. Left column, first trial; right column: second trial. Top row, Raster plot of responses to 350 cycles of a 130 Hz sine wave stimulation of the haltere, with histogram of spike phases below. Vector strengths of Trials 1 and 2 were 0.44 and 0.45, respectively. Middle row, Responses during interstimulus periods in which no haltere stimulation was provided. Bottom row, Responses to 350 cycles of 130 Hz motion of the servomotor with the magnet removed. Rayleigh z test of vector strength shows significant phase locking (α = 0.05) only during haltere stimulation, and not during interstimulus periods or the control experiment with the magnet removed. C, Vector strengths of the eight units that showed statistically significant phase-locking activity in at least one trial. D, Haltere stimulation frequency and mean phase (±angular deviation).