FMRI/EEG study of changes in behavior and brain activity during and after saccade practice
Dyckman, Kara Abad
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Practice can lead to better performance of a task and changes in the neural circuitry underlying task performance. The present study used EEG and fMRI to examine changes in brain activity before, during, and after practice of saccade tasks. Thirty-two participants performed pro- and anti-saccade tasks in the fMRI scanner on the first day of the study. During daily practice sessions over a one-week period, EEG data were recorded as half of the participants practiced the prosaccade task and the other half practiced the antisaccade task. FMRI data were recorded at the end of the practice sessions. Participants who practiced the prosaccade task generated saccades with faster latencies as well as an increased proportion of express saccades. Participants who practiced the antisaccade task had decreased latencies to correct antisaccades and showed improvement in the percent of correct antisaccades in the practice sessions. While many regions of the saccade circuitry remained stable across time, there were regions that showed decreased activity after practice. Right DLPFC, inferior frontal cortex, and cuneus showed decreased antisaccade-related activity at the second test session, regardless of practice group. Precuneus, inferior parietal lobule, and anterior cingulate cortex showed decreased antisaccade-related activity after antisaccade practice only, suggesting that practice results in increased efficiency within the circuitry. Changes were also evident across EEG practice sessions. The prosaccade practice group showed increased preparatory period activity in parietal cortex across sessions, which corresponded to an increase in the proportion of express saccades generated. The antisaccade practice group showed decreased activity in right visual cortex approximately 100ms after stimulus presentation across sessions, which may be associated with top-down modulation of visual cortex to facilitate looking away from the peripheral stimulus. The behavioral and brain imaging techniques used in the current study complemented each other to yield information about how practicing saccade tasks can affect the performance of saccades and the neural circuitry supporting these tasks. Results suggest that changes in brain activity after practice of saccade tasks reflect both (1) decreased reliance on regions supporting cognitive control and (2) increased efficiency in the neural circuitry specific to saccade tasks.