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Decoding the grating position and orientation under lateral eye position using optically pumped magnetometers (OPMs)

Poster Session A - Saturday, March 7, 3:00 – 5:00 pm, Fairview/Kitsilano Ballrooms

Yuri Takaki¹ (pon9q9@g.ecc.u-tokyo.ac.jp), Ryohei Nakayama¹, Tsuda Tomoaki², Koki Yoshida², Kazunori Takahashi², Tomohiro Gomi², Sadamu Tomita², Ayumu Yamashita¹, Jiro Saikawa², Tatsuya Munaka², Kaoru Amano¹; ¹The University of Tokyo, ²Technology Research Laboratory, Shimadzu Corporation

Optically pumped magnetometers (OPMs) have recently emerged as a new class of magnetic sensors for magnetoencephalography (MEG), enabling recordings in physically unconstrained conditions and allowing the investigation of brain activity in naturalistic environments. This technological advancement opens new possibilities for studying cognitive processes difficult to assess with conventional head-fixed SQUID-MEG. During lateral gaze, where gaze and head directions differ, higher task accuracy was reported for stimuli located toward the head direction than for a retinotopically matched but more peripheral-to-the-head stimuli. However, how head direction influences visual cortical processing at the neural level remains unclear, particularly regarding its temporal characteristics in humans, largely due to the head-fixation requirements of conventional MEG systems. To leverage the advantages for studying gaze-related modulations, we employed OPM-based MEG to record brain activity while participants viewed gratings of different positions and orientations during lateral gaze; gaze was fixed at screen center with various head directions. Multivariate pattern analysis was applied to decode stimulus position and orientation from OPM signals, and decoding accuracy was compared across head directions. The results showed that position decoding exhibited high accuracy regardless of head direction, indicating stable positional encoding. In contrast, orientation decoding was significantly above chance in most conditions, with slightly higher performance for stimuli presented near the central visual field than in the periphery, and a trend toward improved classification when the head faced the stimulus. Taken together, these findings suggest that head direction during lateral gaze may influence orientation-related neural representations, while positional encoding remains robust.

Topic Area: PERCEPTION & ACTION: Vision