Fig. 2.

Bidirectional propagation of electrically evoked responses. A: fluorescence image shows the density and arrangement of RGC axon bundles with respect to the electrode array. Arrow indicates the stimulating electrode in C and D. B: electrical images (EIs) from 3 RGCs in a single retina obtained with visual stimulation (no electrical stimulation). All of the axons run in the same direction toward the optic disk. Waveforms on the electrodes indicated with numbers are associated with the shaded RGC. C and D: unidirectional (C) and bidirectional (D) signal propagation after electrical stimulation at the electrode shown by a red circle. Note similarity of unidirectional (C) image to the EI from the shaded cell shown in B. The amplitude of the waveform shown for electrode 6 in A–D was reduced by a factor of 2 relative to the scale bar.