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Fig. 6 | BMC Biology

Fig. 6

From: The amygdala modulates prepulse inhibition of the auditory startle reflex through excitatory inputs to the caudal pontine reticular nucleus

Fig. 6

Photo-stimulation of CeA-PnC excitatory synapses induces PPI. a Representation of the PPI protocols performed using acoustic prepulses (top) or blue light prepulses (middle) in WT mice injected with eYFP only and mice injected with ChR2. The bottom schematic represents the hypothesis being tested. b In all mice, control (acoustic) ASR was assessed using acoustic pulse-alone startling stimulations (black bars). In addition, in WT mice injected with ChR2-eYFP, pulse-alone stimulations were paired with optogenetic stimulation trains of CeA-PnC glutamatergic synapses at 5 Hz (red bars) and 20 Hz (dark blue bars). Similarly, mice injected with the control vector AAV-eYFP were used to test possible blue light-induced heat effects at 5 Hz (white bars) and 20 Hz (gray bars) paired with pulse-alone stimulations. Left, Graph showing no significant main effect of blue light photo-stimulation paired with acoustic pulse-alone stimulations (70–120 dB) on mean basal startle amplitude, among animal groups. There was no effect of viral vector type (F(1,4) = 2.096, p = 0.082) or viral vector × sound intensity interaction (F(1,24) = 0.578, p = 0.944). Right, Graph showing no significant main effect of blue light photo-stimulation paired with 120-dB pulses presented during the PPI task, on mean baseline startle amplitude among animal groups. There was no effect of viral vector type (F(1,4) = 1.250, p = 0.298) or viral vector × sound intensity interaction (F(1,4) = 0.109, p = 0.979). c In all mice, control (acoustic) PPI was assessed using acoustic prepulses (black bars). In subsequent trials, photo-stimulation of CeA-PnC glutamatergic synapses at 5 Hz and 20 Hz replaced the prepulses in mice injected with the control AAV-eYFP vector (white and grey bars) and in mice injected with ChR2-eYFP (red and dark blue bars). The graph shows that only in mice injected with ChR2, optogenetic stimulation used as prepulses elicited PPI values 18–41% of acoustic prepulse, at ISI between 10 and 500 ms. (F(1,14) = 6.152, p < 0.001). N = 8 mice per group. Data are represented as mean ± SEM. *p < 0.05, **p < 0.01

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