Fig. 5: Inhibition of the IO that blocks airpuff US-driven CSpks eliminates eyeblink conditioning.
From: Climbing fibers provide essential instructive signals for associative learning
a, Experimental scheme. Photoinhibition of CFs during airpuff US in CS + US trials. (Duration was randomized to avoid consistently timed rebound excitation; Methods.) Wild-type animals were injected with AAV-CamKII-Jaws in the IO where an optical fiber was also placed to photoinhibit CFs. b, Example sagittal section of cerebellar cortex. Similar expression was seen in eight mice. Jaws (green) is expressed in CF inputs to Purkinje cells (magenta). c, Two example electrophysiological traces from a Purkinje cell with identified SSpks (gray) and CSpks (red) in response to airpuff stimulation (red shading). d, Population histogram of SSpks (gray) and CSpks (red) (n = 29 trials, N = 4 units from 2 mice). e,f, Same as c and d, respectively, but paired with CF-Jaws laser inhibition (green; n = 68 trials, same units as in c and d). Spontaneous SSpk rate pre- and during laser epochs (P = 0.42 NS, paired Student’s t-test, N = 4 units). g, Top: average probability of CSpks in airpuff-only versus airpuff + laser trials (*P = 0.028, paired Student’s t-test, N = 4 units). Bottom: spontaneous CSpk rate pre- and during laser epochs (*P = 0.026, Student’s t-test, N = 4 units). Each circle represents a unit, linked through conditions by a dotted line; the black solid circles and line represent the average. h, The %CR across sessions ± s.e.m. (shadows) with and without CF-Jaws laser inhibition (green and black, respectively, N = 4 mice for both). The %CR at the last learning session: CF-Jaws versus controls, **P = 0.0015, two-sample Student’s t-test. Control animals expressed Jaws in CFs but no laser was presented. i, Average eyelid closure traces ± s.e.m. (shadows) from CS + US trials of the last training session of the experiment shown in h revealing an absence of learning in the laser inhibition condition despite the intact unconditioned reflex to the airpuff US. The shaded rectangle indicates where in the trial the US (red) and the laser (green) appeared. j, Same as for i, but for CS-only trials. The shaded rectangles indicate where US and laser would have appeared.
