Pre-pulse inhibition (PPI) task performance
Startle eyeblink responses were modulated by pre-pulse interval (120/480 ms: F(1,34) = 9.84, p = 0.004) and by condition (passive/active: F(1,34) = 35.98, p < 0.001). Both groups showed PPI to the 120-ms pre-pulse interval versus baseline startle response (no pre-pulse presented) in both the passive and active pre-pulse conditions (passive task: t(18) = 2.72, p = 0.014 HC subjects; t(16) = 5.35, p < 0.001 22q11DS subjects; active task: t(18) = 4.30, p < 0.001 HC subjects; t(16) = 2.58, p = 0.02 22q11DS subjects, Table  2).
Table 2  Electromyographically recorded startle eyeblink responses at baseline (no pre-pulse presented) and following presentations of subtle acoustic pre-pulses at 120- and 480-ms lead intervals Resulting percent change as pre-pulse inhibition (%PPI) or pre-pulse facilitation (%PPF) relative to baseline startle response (standard error mean in parenthesis).
The three-way interaction of pre-pulse interval by attention conditions by group approached significance (F(1,34) = 3.83, p = 0.059; Figure  1). Post hoc testing revealed a differential modulation of sensorimotor gating between groups. HC participants showed a significant increase in PPI in the 120-ms pre-pulse interval when directing attention to the pre-pulse, compared to the passive listening task (t(18) = -2.42, p = 0.026). In contrast, 22q11DS subjects showed a trend towards reduced PPI when directing attention to the pre-pulse (t(16) = -1.80, p = 0.09) at the 120-ms pre-pulse interval compared to the passive listening task. Moreover, 22q11DS subjects showed significantly greater PPF in the passive listening task at the 480-ms pre-pulse interval compared to the active listening task (t(16) = -2.31, p = 0.035). Figure  1 indicates both groups exhibit PPF; however, this differs between conditions, with the HC group exhibiting greater (although statistically non-significant) PPF during the active condition.
Figure 1  Mean percent pre-pulse inhibition or pre-pulse facilitation for 120- and 480-ms pre-pulse lead intervals. Mean percent pre-pulse inhibition (PPI) or pre-pulse facilitation (PPF) for 120- and 480-ms pre-pulse lead intervals relative to baseline startle response (no pre-pulse presented). Note differential attention effects on PPI and PPF between groups depending on performance on an auditory discrimination task on the pre-pulse (active) and not (passive).
The ANOVA revealed no additional significant interactions with none of the following conditions reaching significance: interval by group (F(1,34) = 0.045, p > 0.05); condition by group (F(1,34) = 0.08, p > 0.05) nor interval by condition (F(1,34) = 0.00, p > 0.05).