Figure 1.

Punishing an action when it occurs unsignaled leads to caution about producing the signaled action. A, Performance of signaled active avoidance during two different procedures (AA1 and AA2) that vary only with respect to the consequence of producing ITCs. In AA1, ITCs have no consequence. In AA2, ITCs are punished. Percentage of active avoidance responses (upper), avoidance latency (middle), and ITCs (lower) of a group of mice during AA1 followed by AA2 on consecutive daily sessions. Punishing ITCs virtually abolishes these responses but also delays the timing of the active avoidance latencies with little effect on the percentage of avoidance responses. B, Probability histogram (%) of active avoidance latencies during AA1 and AA2 fitted with an exponential Gaussian. Note the rightward shift of the latencies indicating that the mice delayed their action in a sign of caution. C, Speed traces (mean ± SEM) of active avoidance responses (upper) and escape responses (bottom) during AA1 and AA2 procedures aligned by the CS onset. Escapes are responses driven by the US when mice failed to avoid. Note the faster avoidance responses during AA2 despite starting at a lower baseline. D, Same as C but speed traces are aligned by the response occurrence (crossing into the safe compartment) and baseline speed (before trial onset) is subtracted to show the change in speed (Δ Speed). E, F, Comparison of the peak baseline speed (E) and Δ Speed (F) for avoidance and escape responses during different windows in relation to CS onset. Δ Speed was faster for avoidance response and peaked later during AA2 compared with AA1. G, Avoidance response time onset estimated from the speed traces. Mice begin moving later to avoid in AA2 compared with AA1.