Fig. 11.
Hypothetical performance of an average signal decoder compared with the performance of the historical decoder. We simulated the case where the intracortical microelectrode array was replaced with a single electrocorticographic electrode by averaging the recorded signal over all electrodes. A: as with the historical decoder, we identified IFC and HFC frequency bands for each of the participants from the peri-click SNR in five collection sessions. Note that, to construct the simulated single electrocorticographic electrode signal, we averaged the signals over all low-noise microelectrode array channels before computing the SNR. For participant T6, the HFC frequency band did not emerge in any of the sessions. Therefore, we used only LFC and IFC features to calibrate and use the average signal decoder for T6. B: bar plots show decoding accuracy, as measured by normalized mutual information (CYX), of the historical and average signal decoder for each participant on individual session days and the mean across all sessions (overall). For all participants, the historical decoder outperformed the simulated average signal decoder (P < 0.05, bootstrap test). The same amount of data was used to calibrate and validate both decoders. HFC, high-frequency component; IFC, intermediate-frequency component; LFC, low-frequency component; SNR, signal-to-noise ratio.