Biology subjects

Gou, T.

Publications and source records attributed to Gou, T..

2 recordsLinked to original sources

bioRxiv2026

Afterimages drive a shared visual motion reversal illusion in Drosophila

Illusions expose core computations in perception. In one visual apparent-motion illusion, perceptual direction is reversed when phase-shifted gratings are interleaved with uniform frames. Here, we demonstrate that Drosophila exhibits the same direction reversal reported in mammals. Combining behavior, targeted silencing, two-photon imaging, and modeling, we localize the origin of this illusion to elementary motion pathways. Silencing direction-selective T4/T5 neurons abolishes the reversal, and recordings reveal that downstream wide-field neurons invert their directional preference as interleave duration increases. Replacing periodic gratings with random binary patterns preserves the reversal, implicating afterimages rather than spatial periodicity. Imaging neurons upstream of T4/T5 shows signatures of an afterimage, whose emergence depends on interleave luminance. Critically, dark interleaves suppress afterimages and eliminate both the neural and behavioral reversal, whereas light interleaves preserve or enhance it. Thus, afterimages are central to this shared illusion and explain a deficiency of canonical motion-energy accounts. These results link a classic apparent-motion phenomenon to identified circuit elements and reveal a simple stimulus manipulation that switches an illusion on and off.

neuroscience↗

bioRxiv2024

Adaptation to visual sparsity enhances responses to infrequent stimuli

Sensory systems adapt their response properties to the statistics of their inputs. For instance, visual systems adapt to low-order statistics like mean and variance to encode the stimulus efficiently or to facilitate specific downstream computations. However, it remains unclear how other statistical features affect sensory adaptation. Here, we explore how Drosophilas visual motion circuits adapt to stimulus sparsity, a measure of the signals intermittency not captured by low-order statistics alone. Early visual neurons in both ON and OFF pathways alter their responses dramatically with stimulus sparsity, responding positively to both light and dark sparse stimuli but linearly to dense stimuli. These changes extend to downstream ON and OFF direction-selective neurons, which are activated by sparse stimuli of both polarities, but respond with opposite signs to light and dark regions of dense stimuli. Thus, sparse stimuli activate both ON and OFF pathways, recruiting a larger fraction of the circuit and potentially enhancing the salience of infrequent stimuli. Overall, our results reveal visual response properties that increase the fraction of the circuit responding to sparse, infrequent stimuli.

neuroscience↗