Figure 3

Comparison of neuronal response magnitude before and after the administration of morphine. Neuronal responses to noxious stimulation were evaluated using a sliding window technique, in which a 1-s time window was slid through the entire period of a trial at 1-bin step. The bin counts of each window were compared with those of a baseline window by Student's t-test. Only a change of firing rates from the baseline exceeds the limit of P < 0.01 for at least three consecutive windows were taken as a response. The 'P values' were then converted into the information theory concept surprise by performing logarithmic transformation, i.e., -ln P. The surprise values were also compared using the sliding window method (1-s time window, 0.1-s step, P < 0.01 for three consecutive windows). Significant differences (trapezoid markers along the x-axis) between the response magnitude before (solid lines) and after (dashed lines) morphine administration were observed in all of the recorded areas.