Figure 1. Effects of time of day and eliciting stimulus intensity on the acoustic startle response amplitudes of male rats in a light-dark (LD) cycle. (Values with different letters are significantly different [p < .05]. The first data points have been replotted to improve visualization of the rhythmic the LD differences. Values are M +/- SE. Filled portions of the lower abscissas indicate the dark period of LD cycle.)
