Direction selectivity -the preference of motion in one direction over the opposite -is a fundamental property of visual neurons across species. We find that a substantial proportion of direction selective neurons in the mouse visual system reverse their preferred direction of motion in response to drifting gratings at different spatiotemporal parameters. A spatiotemporally asymmetric filter model recapitulates our experimental observations.Motion detection is a feature common to all visual animals, and recent work has shown strong parallels in these computations across many species 1-9 . Similar circuits in these animals underlie the comparison of visual information at two locations at two points in time, a computation that establishes direction selectivity wherein a neuron preferentially responds to motion in one direction over its opposite, or null, direction. Here, we report neurons in the mouse visual system that respond preferentially to motion in their null direction at different spatial and temporal frequencies.Using data from the Allen Brain Observatory, a large-scale survey of visual responses in the mouse visual cortex recorded using 2-photon (2P) calcium imaging 10 , we analyzed responses to the drifting grating stimulus. This stimulus consisted of full-field sinusoidal gratings moving in 8 directions and at 5 temporal frequencies (TFs), but at a single spatial frequency (SF). Many neurons showed direction selectivity, and among these direction selective neurons we found some that reverse their direction preference in response to gratings at different TFs (Fig. 1A). We use the direction selectivity index (DSI, see Methods) to quantify the strength of direction selectivity at each TF, fixing the preferred and null directions to those determined at the preferred TF (TF pref , the TF evoking the largest mean response). A negative DSI thus indicates a reversal of direction preference (Fig. 1B, C). We term the neurons exhibiting this phenomenon Direction Reversing Neurons (DRNs).We imposed strict criteria to identify DRNs by comparing their responses at their preferred condition (the preferred direction at TF pref , blue box in Fig. 1A) and reversed condition (the TF at which the neuron has its largest mean response in the null direction, orange box in Fig. 1A). Candidate DRNs must have a DSI ≥ 0.3 for the preferred condition and exhibit a larger response to the null than preferred direction at the reversed condition. These neurons must also pass a strict bootstrap test (see Methods) to ensure the reversal is not a chance observation driven by a small number of outlier trials. 708 out of 12,515 direction selective neurons (6%) met these criteria. Furthermore, we observe DRNs in all visual areas recorded ( Fig. 1D) and across all transgenically defined populations available in the dataset (Fig. SI1).