INHIBITION OF FEAR-POTENTIATED STARTLE CAN BE DETECTED AFTER THE OFFSET OF A FEATURE TRAINED IN A SERIAL FEATURE-NEGATIVE DISCRIMINATION

Using the fear-potentiated startle paradigm in rats, 4 experiments exa mined whether the inhibitory effect of a feature is evident after its offset following serial feature-negative discrimination training (A+ a nd X-->A-). When startle probes were presented shortly after the offse t of X on X-->A test trials, the inhibitory properties of X were obser ved immediately after its offset. Furthermore, trace reinforcement of X (X-->+), but not delay reinforcement (X+), disrupted the ability of X to inhibit fear-potentiated startle on X-->A trials. Trace condition ing to X was also retarded after A+ and X-->A- training. These results suggest that the inhibitory properties of the serially trained featur e are present after its offset and raise the possibility that either t emporal information regarding nonreinforcement or poststimulus attribu tes of X acquire inhibitory properties.