Pupillary inhibition of delay during Pavlovian conditioning of paralyzed cats

Abstract

Pavlovian conditioning of the pupillary dilation response was studied in paralyzed cats. Sensitization and differentiation control procedures were used to distinguish between generalized and associative patterns of pupillary responses. In Experiment 1 a tone CS was paired with a shock US for five cats trained with incrementing CS-US intervals of 2.5–16 sec. Experiment 2 consisted of the reanalysis of data from a previous study in which white noise or tone served as the CS and the other stimulus served as a differential stimulus (DS). In Experiment 3 a sensitization procedure preceded differential conditioning of the three additional cats. In the first experiment response latency to peak dilation monotonicly increased with increasing CS-US intervals. Furthermore, one response occurred at CS onset and a second or sometimes alternate response occurred later in the CS-US interval. Only the late, inhibition of delay response distinguished between the CS and DS. Moreover, this delayed response did not occur during the sensitization procedure. The results agree with GSR conditioning studies which suggest that only responses which exhibit inhibition of delay arise from the associative pairing of the CS and US.