Fig. 5. High-speed camera recordings from submucous ganglia reveal the differential sensitivities of individual neurones to specific nAChR-antagonists. (A) High-resolution image of a submucous ganglion stained with the naphthylstyryl-pyridinium dye di-4-ANEPPDHQ (inverted grey scale), showing the individual neurones identified by numbers. The stimulation electrode, indicated schematically, was on an adjacent ganglion to the upper right, out of the field of view. (B) Pixel map of the NeuroCCD-SM camera depicting, in red, the pixels within the area of interest. (C) Experimental protocol. (D) High-speed optical recordings from the ganglion in A. Data are presented in two ways: signals spatially averaged over the whole ganglion [row of bars labelled `Ganglion', whose heights represent the amplitude of the voltage change averaged over the area of interest (red pixels in B)] and signals spatially averaged over individual neurones (`Cells' numbered 1–11). The colours match the conditions illustrated in C and reflect the steady-state responses obtained during successive drug applications (see Fig. 6B,C). Since no absolute membrane potential calibration is possible in this type of experiment, the vertical axis in this and all subsequent optical recordings represents changes in fluorescence intensity in arbitrary units (F). Illumination was reduced 21-fold by inserting neutral density filters in the light path; its duration was limited to 1.8 s per trial. Magnification, 100x. All traces were band-pass filtered between 6.6 and 200 Hz.