Brenda (Siyue) Qiu¹ (), Kristin M. Woodard¹, Bridget Leonard¹, Scott O. Murray¹; ¹University of Washington

The cerebellum has traditionally been associated with motor control, but recent studies also suggest its involvement in cognitive functions, including attention (Brissenden et al., 2016; King et al., 2019). This study investigates how visual spatial attention influences cerebellar neural activity. Functional MRI data were collected from 50 participants completing a motion direction discrimination task. Each trial began with a cue directing participants to attend to the left or right visual hemifield, followed by the bilateral presentation of two Gabor gratings at one of three contrast levels (0%, 6%, or 50%). Participants then reported the motion direction of the attended grating. Cerebellar voxels of interest (VOIs) were identified based on significant differences between peak and baseline activation in the 0% contrast condition, where no grating was shown after the cue, isolating the stimulus-independent attention effects. The identified VOIs revealed an ipsilateral representation of visual spatial attention in the cerebellum, consistent with previous findings (Brissenden et al., 2018). Comparisons of percent fMRI signal change between attended and unattended conditions indicated attentional modulation in lobules VIIb, VIIIa, and VIIIb, as well as in lobules V, VI, Crus I, and Crus II. These findings align with prior research on the cerebellum's role in visual perception and attention (Brissenden et al., 2018; van Es et al., 2019; Brissenden et al., 2021). In cortical visual areas V1 and MT+, we found an additive effect of attention, where the increased neural activity was observed across different contrast levels, similar to previous findings (Murray, 2008). In contrast, cerebellar neural activity was predominantly modulated in the 0% contrast condition. Qualitatively, the gap between attended and unattended contrast response functions diminished as contrast increased. These findings differ from effects typically observed in cortical visual areas and suggest a unique, stimulus-independent role for the cerebellum in spatial attention.

Acknowledgements: This work was supported by funding from the National Institutes of Health (R01MH131595 to S.O.M.)