Figure 3.

A transcriptomics-friendly neuronal activity clamp. A, Maximum intensity projections of confocal image stacks through the antennal lobes of 5-day-old female flies carrying EGFP::Kir2.1 or EGFP::Kir2.1-nc transgenes under GH146-GAL4 and tub-GAL80^ts control. The expression of Kir2.1 constructs is undetectable at 21°C (top) but induced at 31°C (center and bottom). Scale bar, 20 µm. B, Example voltage responses to 5 pA current steps of antennal lobe PNs expressing EGFP::Kir2.1-nc (black) or EGFP::Kir2.1 (red). C, D, Kir2.1 (red) lowers the input resistance R_m (t₍₁₄₎ = 2.1652, p = 0.0481; C) and shortens the membrane time constant τ_m (t₍₁₄₎ = 4.4959, p = 0.0005; D) relative to Kir2.1-nc (black). Circles represent individual PNs. Error bars indicate mean ± SEM. E, Cumulative distribution functions of the percentages of PNs reaching a spike frequency of 30 Hz at different levels of injected current (left); semisaturation currents (middle) and percentages of cells reaching spike rates of 1-50 Hz, for PNs expressing Kir2.1-nc (black) or Kir2.1 (red). F, Circadian locomotor rhythms in constant darkness. Locomotion was quantified as the total number of midline crossings per minute in groups of 16 flies expressing Kir2.1-nc (black) or Kir2.1 (red) under pdf-GAL4 control. The traces were smoothed with a Gaussian kernel (1.25 h FWHM) and show data collected on days 2-5 after the flies were transferred to activity monitors.