Fig. 3. Goal decoding.

(A) Direct goal classification (DGC) task. EGS was instructed to intend motion toward a cued target through a delay period after the target was removed from the screen. Neural activity from the final 500 ms of the delay period was used to decode the location of the spatial target. EGS was awarded points depending on the relative location of the decoded and cued target. The decoded target location was presented at the end of each trial. (B) Symbolic task. A target grid was presented along with a number indicating the current target. The cue was removed during the delay period. A series of tones was used to cue the start and end of movements. Multiple effectors were tested in interleaved blocks. Catch trials provided a means to ensure that EGS was, on average, engaged in the task. (C) Estimated classification accuracy (mean with 95% CI) for variable population sizes. Populations were constructed by using randomly sampled units from the recorded population for the MMR and DGC tasks. Chance based on number of potential targets (MMR: four targets; DGC: six targets). (D) Greedy dropping curves show that high classification accuracy is possible whether targets are cued directly (A) or symbolically (B). Best: best single day performance; Combo: performance when combining data across days.