Figure 1

Infrared inhibition of AP initiation.

(a) A micropipette providing supra-threshold extracellular electrical stimulation to BN2 is flanked by two optical fibers. Extracellular nerve recordings were obtained from the three distal branches. (b) Nerve cross-section schematic at the site of inhibition. (c) Neural recordings from branches of BN2 showing selective inhibition (arrows) of AP generation. Each laser inhibits initiation of an AP projecting to a single nerve branch. Laser 1 (4.43 ± 0.30 J/cm²) inhibits an AP projecting to BN2c, whereas Laser 2 (8.34 ± 0.78 J/cm²) inhibits an AP projecting to BN2b. Upon removal of the infrared pulse, electrically evoked APs return, indicating reversibility. (d) Neural recordings from branches of BN2 showing combined inhibition of two nerve branches. Applying infrared pulses from both lasers simultaneously inhibits APs projecting to BN2b and BN2c (arrows), while electrically evoked APs projecting to BN2a are unaffected. Each trace in (c) and (d) is 30 ms. (e) Average iCNAP recorded from BN2a, BN2b (** p < 0.01) and BN2c (** p < 0.01) in response to electrical only, electrical plus Laser 1 and electrical plus Laser 2 (N = 3 nerves; n = 5 trials). Data are presented as mean ± SEM.