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. Author manuscript; available in PMC: 2015 Nov 6.
Published in final edited form as: Cell. 2014 Nov 6;159(4):751–765. doi: 10.1016/j.cell.2014.09.056

Figure 3. AIY regulates direction-switch by forming an inhibitory circuit with its downstream neuron AIZ.

Figure 3

(A) Schematic showing the major downstream synaptic partners of AIY.

(B) Laser ablation shows that AIZ is required for AIY to promote reversal initiation. Worms expressing NpHR as a transgene in AIY were tested for reversal initiation triggered by yellow light. n=5. **p<0.0001 (ANOVA with Tukey’s HSD test).

(C) Double ablation of AIZ and AIY suppresses the effect of AIY single ablation on promoting reversal initiation. n ≥5. **p<0.0001 (ANOVA with Tukey’s HSD test).

(D–E) Optogenetic inhibition of AIZ activity promotes reversal initiation (D), while optogenetic stimulation of AIZ suppresses it (E). ChR2 and NpHR was expressed as a transgene specifically in AIZ. Control: non-transgenic siblings. n=5. **p<0.0001 (t test)

(F–G) Optogenetic inhibition of AIZ does not affect locomotion speed. Since optogenetic stimulation of AIZ triggered reversal initiation, we were unable to test its effect on locomotion speed. (F) Speed traces. (G) Bar graph. n ≥18.

(H) Calcium and locomotion velocity traces acquired with the CARIBN system. The windows highlighted in green denote reversals.

(I) Cross-correlogram showing that reversal initiation correlates with AIZ activity increase. n=5.

(J) Cross-correlation analysis shows that AIZ calcium activity does not show a strong correlation with locomotion speed. n=5.

(K–L) Inhibition of AIY activates AIZ. Worms carrying two transgenes (one expressing NpHR in AIY and the other expressing GCaMP3.0 in AIZ) were imaged with the CARIBN system. Control: worms carrying the AIZ::GCaMP3.0 transgene only. (K) AIZ GCaMP calcium traces. (l) Bar graph. n ≥6. **p<0.0001 (t test).

(M–N) Stimulation of AIY does not affect the activity of AIZ. Worms carrying two transgenes (one expressing ChR2 in AIY and the other expressing RCaMP in AIZ) were imaged with the CARIBN system. Control: worms carrying the AIZ::RCaMP transgene only. (M) AIZ RCaMP calcium traces. (N) Bar graph. n=6.

(O) Schematic model showing that AIY forms an inhibitory circuit with AIZ to regulate reversal initiation.

All error bars: SEM