Fig. 9.

In vivo recording from ps:LC neurons. (A) Spinally transduced LC neurons were identifiable in vivo on the basis of their response to light pulses (recording position in LC shown post hoc in A₁) (B) ps:LC neurons could be entrained to discharge action potentials by light flashes (445 nm, 2 Hz, 7 ms pulses, 7 mW) and could also be driven to fire at a sustained higher rate by more prolonged illumination (C, 500 ms). (D) In this same recording four LC units were individually discriminable by wavemark templating and shown here separated by principle component analysis (D₁, ovoids mark 2SD from mean). The four units shown D2 all showed excitatory-inhibitory responses to contralateral hindpaw pinch but only two were identified as being spinally projecting by their excitatory response to light pulses (445 nm, 5 Hz, 11 mw, 20 ms).