Fig. 4: Optogenetic activation of RAm Nts neurons drives high-fidelity, short-latency spikes in laryngeal and expiratory muscles.
From: A brainstem circuit for phonation and volume control in mice
a, Schematic of optogenetic stimulation with EMG recording. NtsCre mice were bilaterally injected with AAV-DIO-bReaChES into RAm. An optical fiber delivered yellow laser light into RAm while EMG was simultaneously recorded from laryngeal (CT) and expiratory (EO) muscles and airflow by a spirometer. b, Airflow trace (top), integrated amplitude EMG trace for CT (middle) and EO (bottom) during optogenetic stimulation of RAm Nts neurons (yellow bar, 10 Hz). Note rhythmic inspiratory activity of CT muscle and lack of EO activity during eupneic (normal) breathing before stimulus and then increases in CT and EO EMG activity during optogenetic stimulation, followed by gradual return to pre-stimulation breathing and EMG patterns. c, Quantification of integrated EMG amplitude (amp.) fold change (FC) from pre-stimulation period for CT (top) and EO (bottom) muscles during 0-Hz, 10-Hz, 20-Hz and 30-Hz optogenetic stimulation (n = 3 mice). Note progressive increase in EMG amplitude of both muscles with increasing stimulation frequency. CT: P = 0.0007 and EO: P = 0.008 by linear regression. d, Magnified traces from dashed boxed region in b during optogenetic stimulation pulses (yellow bars). Note short-latency, high-fidelity EMG spikes in both muscles after an optogenetic stimulation pulse but slightly longer latency of EO (~20 ms) versus CT (~8 ms) activation.
