Fig. 10.

Closed-loop optogenetic stimulation triggered on lick detection. A: schematic for closed-loop sensing and optogenetic perturbation of licking during visual perception. Control signals from either the left or right detectors gate delivery of laser light to the left anterolateral motor cortex (ALM) area involved in generating licking. Light activates inhibitory neurons in a transgenic mouse (Pv-Cre × Ai32-ChR2; see methods). In this configuration, right licks are contralateral to the inhibited cortical region. B: lick-triggered optical inhibition of left motor cortex reduces ipsilateral (left) licks within >100 ms of sensing the first lick within a bout. Interleaved control trials (black) show no deficit. Mean lick times per condition indicated with circles [control: 0.16 (SD 0.16) s; stimulated: 0.13 (SD 0.13) s; n = 14 interleaved behavioral sessions each condition]. Inset shows 5 individual trials for each condition during a single session. C: same experiment, during contralateral right licks. Licking frequency is reduced almost immediately (< 0.01 s), and mean lick time is significantly shorter for lick-triggered laser trials vs. control trials [control: 0.25 (SD 0.2) s; stimulated: 0.09 (SD 0.13) s; n = 7 control sessions; n = 14 interleaved optogenetic sessions] in comparison to ipsilateral licks. Inset shows 5 individual trials (tick marks show individual licks) for each condition during a single session.