Superior colliculus peri-saccadic field potentials are dominated by a visual sensory preference for the upper visual field

The primate superior colliculus (SC) is critical for saccade generation ^1-9 , but it also possesses a rich visual processing repertoire ^10,11 . A now-acknowledged property of the SC is that it does not represent all visual field locations equally: besides foveal magnification ^12,13 , SC neurons representing the upper visual field show significantly stronger and earlier visual responses than neurons representing the same retinotopic eccentricities in the lower visual field ^14-16 . Intriguingly, saccade-related motor bursts in the same neurons exhibit the opposite asymmetry: SC motor bursts are stronger in the lower rather than upper visual field ^14,17 . Here, and motivated by evidence of sensory signals embedded within the motor bursts themselves ^11,17-21 , I asked whether a visual sensory preference for the upper visual field in the SC still manifests itself peri-saccadically, despite the weaker motor bursts. Since SC local field potentials (LFP’s) exhibit saccade-related modulations ^18,22-24 , I specifically investigated whether they reflect the visual ^14-16 or motor ^14,17 spiking asymmetries. As expected, LFP’s exhibited strong peri-saccadic negativity at the time of motor bursts ^18,22-24 . Critically, such negativity was much larger in the SC’s upper visual field representation, and it matched the asymmetry in stimulus-evoked LFP negativity. Peri-saccadic LFP modulations thus reflected the SC’s sensory preference for the upper visual field, and they were unambiguously dissociated from peri-saccadic spiking asymmetries. This dissociation persisted even with saccades towards a blank, suggesting that topographic location was a critical determinant. My results suggest that at the time of saccades, the SC network possesses a clear sensory- related signal, potentially relevant for processes beyond just online saccade control.