Figure 5.

Abstraction of regularity over time and shock frequency. Subjects received two shock treatments, starting a day after a spinal transection. One group (720 Same Hz) received 360 FT shocks on each day at the same frequency (0.5 or 2 Hz). Another (720 Different Hz) received 360 FT shocks on each day, but on different frequencies. A third group never received shock (Unshocked). The last group (360 Once) received a single bout of 360 FT shocks, during either the first or second session. Half of these subjects received shock at 0.5 Hz while the remaining received shock at 2 Hz. This experimental design is detailed in the top panel. Subjects were then tested for 30 min with response-contingent shock applied to the untreated leg. As expected, unshocked rats exhibited an increase in response duration over the 30 min of testing (left panel). Exposure to a single bout of 360 FT shocks induced a learning impairment. Two bouts of FT shock eliminated the learning impairment and this was true independent of whether the shocks were given at the same or different frequencies across days. Mean performance, ± SEM, is illustrated in the right panel.