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. Author manuscript; available in PMC: 2021 May 14.
Published in final edited form as: Cell. 2020 May 14;181(4):774–783.e5. doi: 10.1016/j.cell.2020.04.033

Figure 6. Dynamic stimulation tested in blind participant 03–281.

Figure 6.

(A) Still frame from a video of the participant drawing, see Supplementary Video 3 for full video. The participant placed the index finger of the left hand on a tactile fixation point and used the index finger of the right hand to trace the visual percept on the touch screen. (B) Medial view of a surface model of the participant’s right occipital lobe. Dashed line shows calcarine sulcus, circles show electrode locations and labels. (C) Blue ellipses show participant drawing of phosphenes created by stimulation of individual electrodes, with labels corresponding to electrodes in (B). (D) Dynamic stimulation pulse diagram. The timing of the pulses to the first three electrodes in a sequence are shown; pulses to successive electrodes occurred with the same timing. Currents ranged between 3.5 and 5.8 mA per electrode. (E) Four different letter-like shapes created by four different dynamic stimulation patterns. The left panel for each shape shows the temporal sequence of stimulation (electrodes indicated by numbers connected by black arrows). The right panel for each shape shows the participant drawing for each stimulation pattern along with verbal label. (F) Participant drawings for ten different trials of each stimulation pattern, each trial indicated with a different color. (G) Quantification of the drawings produced by the participant for each trial of each stimulation pattern using multidimensional scaling analysis. Each letter corresponds to a single trial of the corresponding stimulation pattern. Boldface letters show the centroid of each cluster from a k-means analysis. (H) Accuracy of form identification at two different presentation rates. Left bar: two forms (a downward line and an upward line) were presented in random order at 85 forms per minute and verbally identified by the participant. Right bar: three forms (“C”, “U”, backwards “C”) were presented at 30 forms per minute. Error bars show 95% confidence interval from binomial distribution. See Supplementary Video 4 for full video.