Figure 9.

ECoG relative power (or LFC) for fastest movements to different directions: 2-D task. Velocity tuning of (A) high γ (55–300 Hz), and (B) low γ (30–45 Hz). (C) β (13–30 Hz), (D) α (8–12 Hz), (E) δ (0–4 Hz) power modulations, and (F) the time-domain LFC (0–4 Hz). Movement directions are indicated by arrows. The ECoG grid schema of subject S7 with ESM labels (same annotation as in Fig. 5) is shown in the middle of B. Significantly tuned ECoG channels (P < 0.001) were compared (by R²) with the “perfect” 2-D velocity- and speed-type tuning profiles. The angle of the dashes (defined as arctan $(R_{\mathrm{speed}}^2/R_{\mathrm{velocity}}^2)$) indicates the degree of speed-type (vertical orientation) or velocity-type (horizontal orientation) tuning. The ECoG power modulation is relative to that of zero velocity. Consistent with the 1-D car-driving task, relative power in high-frequency bands (>50 Hz) increased irrespective of movement direction, accompanied by a simultaneous power decrease in lower frequencies (<50 Hz), in the 2-D target pursuit task as well. Similarly, the LFC showed large-scale, dipole-like activation patterns.