Change of the LFP power as a function of recording depth. (A and B) Normalized LFP data (8–15 Hz) with alignment at target onset (Left) and saccade onset (Right) for monkey P and monkey S, respectively. The LFP data from both monkeys showed that following the increase of recording depth, the visual evoked potential decreased (A and B, Left), whereas the saccade evoked potential increased (A and B, Right). The linear regression analysis of the averaged change of energy power of the lower frequency showed a negative correlation between visual evoked potential and recording depth (C; slope = −0.667, R = −0.325, P = 0.004) and a positive correlation between saccade evoked potential and recording depth (D; slope = 0.517, R = 0.224, P = 0.048).