Figure 6. B-type cholinergic motor neurons are required for transducing the proprioceptive signal.

(A) Video images of a transgenic worm (Punc-17::NpHR) partially trapped in a pneumatic microfluidic channel. Green bar indicates the duration of green light illumination of the middle portion of the worm before and after induced change in channel curvature at t = 0 s. As a result, the curvature of the tail failed to follow the curvature change of the channel (also see Movie S8).

(B) Curvature kymogram of the transgenic worm trapped in the channel as shown in (A). Green shading indicates the body region and duration of green light illumination.

(C) Curvature of the posterior body region, measured as an average from the posterior limit of the channel to the tail, during onset of illumination (green shading) and the induced change in curvature of the middle region at t = 0 (dashed line). Representative data from five worms were shown. Red curve corresponds to the experiment shown in (A) and (B). A comparison with Figure 5D shows that posterior body region did not switch its curvature after induced curvature change in the trapped middle region during green light illumination.

(D) Video images of a Pacr-5::twk-18(gf)-UrSL-wCherry transgenic worm partially trapped in a static microfluidic channel. B-type cholinergic motor neurons in this strain were specifically deactivated due to the expression of an active K⁺ channel.

(E) Curvature kymogram of the partially trapped worm shown in (D) during periods of forward movement. A comparison with Figure 3b shows that the posterior body region emerged from the channel no longer follow the curvature of the middle region imposed by the channel.

(F) The mean curvature of the posterior body region emerged from the microfluidic channel in wild type (n = 8) and Pacr-5::twk-18(gf)-UrSL-wCherry transgenic worms (n = 9) during forward movement. All worms were partially trapped in the channel with a curvature 6–8 mm⁻¹. *** p < 0.001, Mann-Whitney U test.