Figure 5.

Muscarinic receptors mediate light-induced suppression of ripple oscillations. A, Intraperitoneal injection of atropine successfully rescued light-induced suppression of ripple oscillation. Top, Power spectrogram of 4000 s continuously recorded LFP (red triangle, atropine injection; blue bar, light stimulation). Bottom, Enlarged view of the pink boxed area with additional bandpass-filtered ripple oscillation, showing the rescue effect before (left) and after (right) atropine injection. Calibration: Ripple, 0.2 mV; Ripple_N, 0.2 mV. B, Ripple inhibition is significantly decreased after atropine injection, including ripple incidence (top) and power (bottom) inhibition (mean ± SD; n = 5 mice; paired t test, ripple events inhibition index: **p = 1.7e-3, t = 7.44; ripple power inhibition index: **p = 2.0e-3, t = 7.16). C, D, Same as A and B, but for intraperitoneal injection of MEC. MEC could not rescue the light-induced suppression of ripple oscillation as there is no significant difference in the reduction of ripple events as well as ripple power before and after MEC injection (D; mean ± SD; n = 6 mice, paired t test; n.s., not significant; ripple events inhibition index: p = 0.54, t = 0.65; ripple power inhibition index: p = 0.22, t = 1.41). Calibration: Ripple, 0.2 mV; Ripple_N, 0.2 mV.