Figure 7. Dbx1 preBötC neurons with premotor function.
(A) Fluorescence and (B) bright field images of a slice preparation. Anatomical landmarks are illustrated including: XII, the hypoglossal motor nucleus; scNA, semi-compact division of the nucleus ambiguus; IOPloop, the ventral loop of the principal inferior olive, and the ventral surface of the preBötC. Scale bar is 100 µm and applies to A and B. A patch-recording pipette is visible, marking the inspiratory-modulated neuron detailed in C–E. A dotted circle indicates the tip of the pipette and cell body. (C and D) tdTomato expression, intracellular dialysis of Alexa 488, and merged image (C) from the inspiratory neuron shown with XII nerve output (D). Voltage and time calibration bars represent 20 mV and 1 s. Baseline membrane potential in the recorded neuron was −60 mV. (E) Antidromic activation of the Dbx1 inspiratory neuron from C and D. Action potentials were evoked by XII stimulation (left) and intracellular 5-ms supra-threshold current pulses (middle). When the antidromic XII stimulus was preceded immediately by a supra-threshold intracellular current pulse, the antidromic spike was occluded (collision test, right). Several sweeps, all from a −62 mV baseline membrane potential, are superimposed with vertical offset in each case. Voltage calibration is the same as panel D. Applied current (Iapp) calibration is shown. Time calibration bar for E is 25 ms.