Figure 1. Recording whisking and facial mechanosensory afferent spiking.
(A) Schematic of types of afferents (open circles with dotted lines) recorded, grouped by type of receptive field: trigeminal ganglion (TG, beige) low threshold mechanoreceptors (LTMRs) with receptive fields localized to (1) a mystacial whisker follicle (filled black dots; e.g. black whisker), (2) hairy skin (e.g. gray patch on cheek), or (3) a non-mystacial vibrissa (red dots; e.g. black supraorbital vibrissa), and trigeminal mesencephalic nucleus (MeV) proprioceptors innervating facial muscles. (B) Schematic of experimental setup. A head-fixed mouse ran on a treadmill and whisked in air. Single neurons were recorded simultaneously with high-speed (500 Hz) video of the whiskers. (C) Example video frame, capturing the silhouette of the whiskers and profile of the mouse face, and illustrating measurement of the angular position of a whisker (θ) relative to the mediolateral axis. (D) Example traces showing one second of whisker angular position (θ), whisking midpoint (θmid), amplitude (θamp; bottom of scale bar indicates 0°), and phase (Φ; gray vertical lines, times when the whisker is fully retracted, Φ = π). (E) Overview of dataset, including the number of units recorded and the number of each type that were whisking-sensitive (Glossary).