Fig. 3

Characterizing intracellular and extracellular responses. a Representative plot of membrane potential before, during, and after the addition of 10 µM of the proton uncoupler BAM15 (n = 6). The neuron was penetrated by the thermal probe before the addition of BAM15. b Control experiments with BAM15 show a maximum extracellular temperature rise of 1.2 ± 0.6 K that decays over ~8 min. Extracellular responses were measured with the thermal probe placed just outside the cell membrane of a target neuron (n = 6). Heat of mixing between BAM15 and saline was measured in the absence of a ganglion (n = 6). c A representative injury discharge (n = 6) that is observed as the thermal probe enters the cell. All the intracellular data plotted in Fig. 4 are from experiments that recorded a positive injury discharge response, indicating the probe’s presence inside the cell