EEG Activity during Pursuit and Saccade Visual Strategies to Predict the Arrival Position of a Target.

BACKGROUND: In this study, we used electroencephalogram (EEG) to investigate the activity pattern of the cerebral cortex related to visual pursuit and saccade strategies to predict the arrival position of a visual target. In addition, we clarified the differences in the EEG of those who could predict the arrival position well using the saccade strategy compared to those who were not proficient. METHODS: Sixteen participants performed two tasks: the "Pursuit Strategy Task (PST)" and the "Saccade Strategy Task (SST)" while undergoing EEG. For the PST, the participants were instructed to follow the target with their eyes throughout its trajectory and indicate when it reached the final point. For the SST, the participants were instructed to shift their gaze to the end point of arrival once they had predicted it. RESULTS: Low beta EEG activity at the Oz, Cz, and CP2 electrodes was significantly higher during the SST than during the PST. In addition, low beta EEG activity at P7 electrode was significantly higher in the group showing a small position error (PE) than in the group showing a large PE at response. CONCLUSIONS: EEG activity at the Oz, Cz, and CP2 electrodes during the SST may reflect visuospatial attention to the moving target, the tracking of moving targets, and the focus on the final destination position. In addition, EEG activity at P7 electrode may more accurately detect the speed and direction of the moving target by the small PE group at response.

The presence of occlusion affects electroencephalogram activity patterns when the target is occluded and immediately before occlusion.

OBJECTIVE: The objective of this study was to clarify the differences in electroencephalogram (EEG) activity patterns during the eye movements required to trace visible and occluded moving targets with millisecond temporal resolution. METHODS: To achieve this objective, we simultaneously measured EEG and eye-tracking during a task that required tracking moving targets that were partially occluded. These EEG and eye tracker parameters were compared with those of a nonoccluded task, a control task in which the moving target was fully visible. RESULTS: Differences in EEG activity patterns in the parietal eye field and posterior parietal lobe were observed during the occluded sections in the occluded task compared with the nonoccluded task. Under the same conditions, differences in EEG activity patterns in the middle temporal visual area, posterior parietal lobe, premotor, primary motor cortex, and temporal lobe were observed during visible sections in the occluded task compared with the nonoccluded task. CONCLUSION: These results indicate that the presence of occlusion affects EEG activity patterns not only when the target is occluded but also immediately before occlusion.

Effects of prefrontal activity during the preparatory period on success or failure of response inhibition in the stop-signal task.

We examined the mechanism by which contingent negative variation (CNV) amplitude in the prefrontal cortex during the preparatory period of a stop-signal task affected the accuracy of response inhibition in the task. The participants were required to press a button when a go signal was presented and withhold the response when the go signal was followed by a stop signal. Continuous electroencephalograms were recorded of the six electrodes (Fz, F3, F4, Cz, C3, and C4) in the regions of interest during the performance of the task. First, the fast and slow go responses in the preparatory periods were compared. The activities in the preparatory periods of the successful and failed inhibitions were then compared and analyzed. The late CNV amplitudes of F4 and Cz were significantly larger for fast go responses than for slow go responses. Moreover, the late CNV amplitudes of almost all of the channels, with the exception of C3 and C4, were significantly larger for failed inhibitions than for successful inhibitions. These findings suggested that increased prefrontal activity during the preparatory period facilitated the execution process after the presentation of the go signal. Because execution processing is completed more quickly than stop processing, the response inhibition then failed.

Effects of training the coincidence-anticipation timing task on response time and activity in the cortical region.

We examined the effects of training the coincidence-anticipation timing task on response time and activity in the cortical region. The task, which used a partially masked stimulus runway, required 12 participants to press a button at the time that they anticipated a moving visual target would arrive at the end of the runway. Training involved practicing the task a total of 10 times (once per day) over a 3-week period. Continuous electroencephalograms were recorded while performing the task before training and after training. The electroencephalograms were subjected to fast Fourier transform to obtain the power density in the beta bands. Peak amplitude and peak latency of event-related potentials were also determined. The results showed that, compared with before training, in the masked section of the task, the percentage of beta band activity was significantly increased in Brodmann's area 6 and significantly decreased in Brodmann's area 46 bilaterally after training. In addition, peak latency was significantly shorter in Brodmann's area 6 after training. These findings suggest that activation of Brodmann's area 6 in the masked section of the task after training might reflect the transfer from processing visual information of the moving target in the visible section of the task to predicting the target's movement in the masked section. In addition, the shortened peak latency in Brodmann's area 6 after training might reflect facilitation of information processing, which is why the mean absolute error was decreased after training.

Beta band patterns in the visible and masked sections of the coincidence-anticipation timing task.

In this study, we examined beta band patterns during the coincidence-anticipation timing task. The tasks were the coincidence-anticipation timing task using a partially masked stimulus runway and a control task using the stimulus runway with no masking. Both tasks were displayed on a computer screen placed 1.3 m in front of the participants while they were seated in an armchair. Ten healthy right-handed adult men were asked to press a holding push button with their right thumb when a downward-moving visual target arrived at the end of each task. The electroencephalogram during both tasks was divided into three segments: the visible section, the first half of the masked section, and the second half of the masked section. The valid epochs were subjected to fast Fourier transform to obtain the power density in the beta bands. Power in the beta bands was expressed as a percentage of the total power (3-30 Hz) in each segment. The results showed that the percentage of beta band activity in Brodmann's areas 7 and 19 was significantly increased in both the visible and the masked sections of the coincidence-anticipation timing task compared with the control task. These results suggest that Brodmann's areas 7 and 19 mainly contribute toward attention to visual targets in the visible section and to movement prediction of moving visual targets in the masked section. In addition, Brodmann's areas 9 and 10, which were inactive, might affect the response time in the masked section during the coincidence-anticipation timing task.