Research Fellow Children’s Hospital of Michigan Farmington Hills, Michigan
Rationale: Saccadic suppression, a transient reduction of visual sensitivity during rapid eye movements, is an essential mechanism underlying stable visual perception. The present study generated the whole-brain level dynamic atlas of saccadic suppression based on the modulations of intracranially-recorded high-gamma activity. By modeling the relationship between saccade behaviors, cortical organization, and high-gamma modulations during and around spontaneous saccades, we clarified the cortical mechanism underlying saccadic suppression in the human brain. Methods: We studied 30 patients (age: 5-20 years) who underwent intracranial EEG (iEEG) and electrooculography (EOG) recordings. Time-frequency analysis computed saccade-related high-gamma amplitude (70-110 Hz) at 2,313 nonepileptic electrode sites, defined as those outside the seizure onset zone, spiking zone, and structural lesions. We then tested the hypothesis that saccade-related high-gamma modulations would localize the primary visual cortex defined by electrical stimulation mapping (ESM). Results: The mean duration of saccades was 119 ms to the left (SD: 28.6 ms) and 122 ms to the right (SD: 29.1 ms), respectively. The dynamic atlas demonstrated a transient high-gamma suppression involving the striate, lateral-occipital, and fusiform regions between saccade onset and offset. Following saccade offset, high-gamma suppression lingered in the lateral occipital region, whereas high-gamma augmentation took place in the striate and fusiform regions. High-gamma suppression was intense at striate sites proximal to the pole, ipsilateral to the direction of given saccades, and in patients whose saccade duration was long. The root mean square magnitude of saccade-related high-gamma modulations (either augmentation or suppression) successfully localized the ESM-defined primary visual cortex with an accuracy of the mean area under the curve of 0.88 on average across patients (95%CI: 0.82-0.93). Conclusions: Transient suppression of the primary visual cortex may be, in part, responsible for saccadic suppression. Saccade-related neuronal suppression may take place more intensely in the visual cortex processing less attended hemifields. For clinicians, assessment of saccade-related high-gamma modulations may be useful to localize the primary visual cortex. Funding: Please list any funding that was received in support of this abstract.: NIH grant NS064033. Click here to view image/table
