Cortical activation patterns during voluntary blinks and voluntary saccades

Objective: To investigate the activation of frontal, parietal, and occipita l areas in normal volunteers during voluntary blinks and during voluntary s accades using functional MRI (fMRI). Background: A previous fMRI study reve aled the activation of the precentral and posterior middle frontal gyrus (" frontal eye field" [FEF]), the medial part of the superior frontal gyrus (" supplementary eye field" [SEF]), and the visual cortex. The parietal cortex was not included in this study. Frontal and occipital cortical areas invol ved in voluntary blinking have not been shown previously using fMRI. Method s: A 1.5-T standard clinical scanner was used for both anatomic and functio nal studies in 12 observers. To conduct data analyses the authors used voxe l-by-voxel cross-correlation. Results: Voluntary blinks led to the activati on (p < 0.05) of the FEF, the SEF, the posterior parietal cortex ("parietal eye field" [PEF]), and the visual cortex. Voluntary blinking produced acti vity in the same cerebral structures as voluntary saccades. However, the nu mber of activated voxels was smaller during voluntary blinking than during voluntary saccades in the visual cortex and in the FEF (p < 0.01). In contr ast, the extent of activation was significantly higher (p < 0.003) in the S EF and in the PEF during voluntary blinking. Conclusions: Voluntary blinks and saccades are associated with similar loci of activation patterns; howev er, the quantitative distribution of activation suggests that the middle pa rt of the frontal gyrus and posterior parietal cortex are of special signif icance for voluntary blinks. The results argue for the importance of consid ering quantitative distributional properties of parallel cortical activitie s associated with saccades and blinks.