Figure 6. Unit recording with concurrent ChR2 or Arch activation.

(a) Schematic showing cannulae implantation at a 27° angle and vertical electrode placement to record from units within the cone of light (473 nm or 593 nm) in opsin-transfected mice. (b) Representative airflow traces (red) and respiratory-modulated units (blue; i) expiratory, ii) inspiratory, iii) pre-inspiratory, iv) pre-inspiratory, v) inspiratory) showing strong inhibition during 1s continuous laser pulse (black bar). Black arrows indicate the expected onset of inspiration following photostimulation. In total, 18 neurons were recorded from 3 mice. (c) Representative recording of multiple units following photostimulation of ChR2-expressing preBötC GlyT2 neurons with airflow trace. Inset: Shorter time-scale at onset of continuous laser pulse (black line) showing large field potential within ~2 msec. Vertical black line shows alignment of laser onset and initial artifact on trace. (d) Response of preBötC neurons to photoinhibition of Arch-expressing preBötC GlyT2 neurons with 1 s continuous laser pulse (black line). Black arrows indicate the expected onset of inspiration following photoinhibition as measured on the airflow trace. In total, 12 neurons were recorded from 2 mice.