Effects of muscimol injection into and/or microstimulation of the PIN on eyelid CRs evoked in well trained animals. Records were performed 1 d after the 10th conditioning session. A, CRs evoked by the single presentation of the CS without (control) and after the injection of muscimol (1.25 μg/kg). Note the smaller (n = 30; ^***p < 0.001; Student's t test) amplitude of CRs evoked under muscimol (histograms on the right). B, Eyelid responses evoked by electrical microstimulation (St) of the PIN without (control) and after injection of the drug. Note that in this case the amplitude of evoked eyelid responses was similar in the two situations (n = 30; Student's t test; histograms on the right). C, CRs evoked by the single presentation of the CS without (control) and after injection of the drug in the presence of the electrical microstimulation of the PIN. Note that there was no significant (n = 30; Student's t test) difference in the amplitudes of the evoked CRs in the two situations (histograms on the right).