2.3. Behavioural Study—Prepulse Inhibition Test

The prepulse inhibition (PPI) test was performed two times: (1) when the offspring were at PND90 and (2) after chronic 14-day administration of antipsychotics. The PPI procedure was adopted with some modifications from our previously published studies [16,20,21]. The examinations were performed in eight sound-proof, ventilated startle cabinets (SR-LAB, San Diego Instruments, San Diego, CA, USA) with a single Plexiglas cylinder (inner diameter of 9 cm) attached to a moveable platform in each of them. A startle reflex was elicited in response to a sound generated by a high-frequency loudspeaker, producing both continuous 65 dB background noise and various acoustic stimuli, mounted inside each chamber. Platform movements resulting from the startle reaction were detected for each animal by a piezoelectric accelerometer during the 200 ms recording window. The data were digitised and used for subsequent calculations, where the maximum startle response (V_max) and average startle amplitude (AVG) were further analysed.

Before the experiments, each chamber was individually calibrated using the external sensor to display a similar readout of the reference stimulus. After five minutes of habituation to the background noise, four types of acoustic stimuli were used in random order. Each trial consisted of either a single pulse alone [intensity 120 dB, duration 40 ms, (P)] or a pulse preceded by a prepulse at one out of three intensities [70, 75 and 80 dB; duration 20 ms; (PP)] applied 80 ms before a pulse. During each experimental session, 20 trials of each type were displayed with an interstimulus interval of 20 s. The V_max and AVG were recorded, and the percentage of PPI (%PPI) induced by each prepulse intensity was calculated as %PPI = [(P − PP)/P] × 100%.