Superior colliculus visual neural sensitivity at the lower limit of natural self-induced image displacements

Abstract

Visual pattern analysis relies on computations from neurons possessing spatially confined receptive fields. Often, such receptive fields are orders of magnitude larger than the visual pattern components being processed, as well as these components’ minute displacements on the retina, whether due to small object or self motions. Yet, perception effortlessly handles such visual conditions. Here, we show that in the primate superior colliculus, a brain structure long associated with oculomotor control, neurons with relatively large receptive fields are still sensitive to visual pattern displacements as small as 1 min arc. We used real-time gaze-contingent retinal image stabilization to control the instantaneous spatio-temporal luminance modulation of detailed patterns experienced by neurons, probing sensitivity to the lower limit of natural self-induced image displacements. Despite a large difference between pattern displacement amplitudes and receptive field sizes, collicular neurons were strongly sensitive to the visual pattern consequences of the smallest possible eye movements.

Microsaccadic suppression of peripheral perceptual detection performance as a function of foveated visual image appearance

“…For the grating images, this likely reflected the vertical orientation of the gratings, since orthogonal eye movements to the luminance gradient would be expected to give rise to the most useful information to the visual system about the underlying image (Rucci, Iovin, Poletti, & Santini, 2007). This is also consistent with neurophysiological signatures of microsaccade-induced visual reafferent responses at extra-foveal eccentricities, in which orthogonal eye movements scaled to a given spatial frequency give rise to the clearest modulations (Hafed, Chen, & Khademi, 2022; Khademi et al, 2020). For the white fixation spot, there were slightly more vertical eye movements than with the gabor gratings (likely reflecting the square appearance of the fixation spot, which includes both horizontal and vertical edges); nonetheless, the overall predominantly horizontal signature of eye movement directions with the white fixation spot was consistent with previous reports (Engbert & Kliegl, 2003; Laubrock et al, 2005).…”

Faster detection of “darks” than “brights” by monkey superior colliculus neurons

“…The fact that SC neurons can be strongly sensitive to dark contrasts is also interesting with respect to spatial frequency tuning in SC neurons. In recent work, we found that SC neurons can be sensitive to minute phase shifts of spatial frequency gratings, as small as 1 minute of arc in amplitude (Hafed et al, 2022). It would be fruitful, in light of these observations and the current work, to investigate RF subfield structure in more detail, for example, to study phase tuning in SC neurons.…”