Fig. 7. An ON cell’s response corresponded better to the presence or absence and magnitude of a withdrawal response rather than the stimulus per se . Responses to three identical thermal stimulus presentations, in which little to no response occurred during the trial where no withdrawal was detected (middle , bottom ). For the two withdrawals, the larger ON-cell response is associated with a larger withdrawal (first vs.  third trial). Raw single-unit  and force traces  are shown on an expanded time scale above the peristimulus histograms (bin width = 1 s) for the two trials during which a withdrawal occurred. Note that the pattern of the response reflects the pattern of the withdrawal.