Fig. 1

Suppression of contraction-related signals by blebbistatin (Bleb). a, b Optical action potentials simultaneously detected by two elements of the photodiode array. The leftmost traces were recorded in a normal solution at 700 nm (Control). The center traces were recorded at 1 h after the application of Bleb (20 μM) at 700 nm. The right two columns of traces were recorded at 2 h after the application of Bleb at 700 and 620 nm, respectively. The arrowheads and filled circles indicate optical action potentials and contraction-related signals, respectively. In this and subsequent figures, the outputs of individual photodiodes have been divided by the resting light level (d.c.-background intensity = fractional change [ΔI/I]). The direction of the arrows on optical traces indicates a decrease in transmittance, and the length of the arrows represents the stated value of fractional change. Note that the vertical calibration is different between the leftmost traces and others. Bottom right Sketch of the preparation illustrates the location of the photodiode array on the preparation. Large square Position of the photodiode array, filled squares indicated by a and b positions of the pixel where the traces shown are recorded. The position of the stimulating electrode is indicated by an open triangle labeled Stim