Figure 1.

Speech task and representative spoken and neural responses. A, Intraoperative syllable speech task. Subjects were asked to read aloud words presented on a computer screen. Each trial consisted of a sequence beginning with the fixation cross turning green for 250 ms, followed by a variable delay black screen (500–1000 ms), and followed by a unique CVC syllable cue appearing on the screen until the response was recorded. A white fixation cross appeared during the intertrial interval. B, An example audio spectrogram time-aligned to the onset of a subject's utterance of the syllable “loath”. The time (in seconds) of cue presentation is indicated by the solid vertical line, and the response onset and offsets are indicated by dotted lines. C, A single unit recording from the subject's STN, showing an increase in firing during speech. Red hash marks indicate timing of detected spike waveforms from the background activity. D, Overlay of 50 spike waveforms from the single unit shown in C. Scatterplots of the first two principal components (E; principal component1 and principal component2), as well as the first principal component and spike timestamp (F), showing clear separation of single-unit spike waveforms (red) corresponding to the example shown in C from background (blue).