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bioRxiv · 10.64898/2026.04.06.716792

A transient signal in foveal superior colliculus neurons for jumpstarting peripheral saccadic orienting

Zhang, T.·Denninger, A. F.·Hafed, Z. M.
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Abstract

The superior colliculus (SC) both senses the environment and orients gaze within it. While the SCs sensory and motor bursts appear qualitatively similar to each other, population activity structure in the two processing regimes (visual and motor) is very different, necessitating a hitherto unexplored rapid representational transformation, occurring on the scale of only tens of milliseconds. Here, we first show that when a planned saccade is released with a go signal, peripheral SC neurons representing the saccade target location exhibit a transient, short-latency pause right before their motor bursts eventually emerge. This pause starts within [~]50 ms from the go signal; it is stimulus-dependent; and it is significantly weaker in purely visual SC neurons than in saccade-related ones. Foveal SC neurons, on the other hand, transiently burst, and their bursts lead the peripheral neurons pauses by [~]10 milliseconds. These transient foveal bursts also lead the same foveal neurons saccade-related pauses, which are time-locked to movement generation. Remarkably, during immediate visually-guided saccade tasks, requiring a transformation from visual to motor peripheral bursts in <50-100 ms, the transient foveal SC bursts still occur, resulting in simultaneous short-latency bursting at two disparate SC loci: one foveal; and one eccentric and responding to the visual appearance of the saccade target. Our results suggest that in classic saccade tasks used to investigate visual, motor, and cognitive processes in primate brains, a transient foveal SC signal precedes peripheral saccadic orienting, and may facilitate a necessary rapid representational transformation needed for SC saccade motor bursts to ensue. SignificanceSaccade control studies often involve behavioral paradigms dissociating stimulus presentation, deliberation epochs, and "go" instructions. While the stimulus presentation, deliberation, and actual movement aspects have been well studied, the "go" phases of trials are less considered. We show that foveal superior colliculus neurons exhibit transient activity bursts at the "go" instruction for saccades, likely enabling a rapid representational transformations from a visual to a motor regime in the extrafoveal collicular neurons driving the eye movements.

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Zhang, T., Denninger, A. F., Hafed, Z. M.. 2026-04-08. A transient signal in foveal superior colliculus neurons for jumpstarting peripheral saccadic orienting. https://doi.org/10.64898/2026.04.06.716792

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