Highlights d Mouse visual cortex is jointly activated by eye, body movements, and visual stimuli d Stimulus and movement responses sum supralinearly; eye and body movements sum sublinearly d Sustained attention increases response-interaction amplitudes and their separability d Sustained attention modulates spatial profiles of both interaction responses

Binocular disparity is an important cue for depth perception. To correctly represent disparity, neurons must find corresponding visual features between the left- and right-eye images. The visual pathway ascending from V1 to inferior temporal cortex solves the correspondence problem. An intermediate area, V4, has been proposed to be a critical stage in the correspondence process. However, the distinction between V1 and V4 is unclear, because accumulating evidence suggests that the process begins within V1. In this article, we report that the pooled responses in macaque V4, but not responses of individual neurons, represent a solution to the correspondence problem. We recorded single-unit responses of V4 neurons to random-dot stereograms of varying degrees of anticorrelation. To achieve gradual anticorrelation, we reversed the contrast of an increasing proportion of dots as in our previous psychophysical studies, which predicted that the neural correlates of the solution to correspondence problem should gradually eliminate their disparity modulation as the level of anticorrelation increases. Inconsistent with this prediction, the tuning amplitudes of individual V4 neurons quickly decreased to a nonzero baseline with small anticorrelation. By contrast, the shapes of individual tuning curves changed more gradually so that the amplitude of population-pooled responses gradually decreased toward zero over the entire range of graded anticorrelation. We explain these results by combining multiple energy-model subunits. From a comparison with the population-pooled responses in V1, we suggest that disparity representation in V4 is distinctly advanced from that in V1. Population readout of V4 responses provides disparity information consistent with the correspondence solution.

During perceptual decision-making, the brain encodes the upcoming decision and the stimulus information in a mixed representation. Paradigms suitable for studying decision computations in isolation rely on stimulus comparisons, with choices depending on relative rather than absolute properties of the stimuli. The adoption of tasks requiring relative perceptual judgments in mice would be advantageous in view of the powerful tools available for the dissection of brain circuits. However, whether and how mice can perform a relative visual discrimination task has not yet been fully established. Here, we show that mice can solve a complex orientation discrimination task in which the choices are decoupled from the orientation of individual stimuli. Moreover, we demonstrate a typical discrimination acuity of 9°, challenging the common belief that mice are poor visual discriminators. We reached these conclusions by introducing a probabilistic choice model that explained behavioral strategies in 40 mice and demonstrated that the circularity of the stimulus space is an additional source of choice variability for trials with fixed difficulty. Furthermore, history biases in the model changed with task engagement, demonstrating behavioral sensitivity to the availability of cognitive resources. In conclusion, our results reveal that mice adopt a diverse set of strategies in a task that decouples decision-relevant information from stimulus-specific information, thus demonstrating their usefulness as an animal model for studying neural representations of relative categories in perceptual decision-making research.

Perception is an active process involving continuous interactions with the environment. During such 1 interactions neural signals called corollary discharges (CDs) propagate across multiple brain regions 2 informing the animal whether itself or the world is moving. How the interactions between concurrent 3CDs affect the large-scale network dynamics, and in turn help shape sensory perception is currently 4 unknown. We focused on the effect of saccadic and body-movement CDs on a network of visual 5 cortical areas in adult mice. CDs alone had large amplitudes, 3-4 times larger than visual responses, 6 and could be dynamically described as standing waves. They spread broadly, with peak activations in 7 the medial and anterior parts of the dorsal visual stream. Inhibition mirrored the wave-like dynamics 8 of excitation, suggesting these networks remained E/I balanced. CD waves superimposed sub-linearly 9and asymmetrically: the suppression was larger if a saccade followed a body movement than in the 10 reverse order. These rules depended on the animal's cognitive state: when the animal was most 11 engaged in a visual discrimination task, cortical states had large variability accompanied by increased 12 reliability in sensory processing and a smaller non-linearity. Modeling results suggest these states 13 permit independent encoding of CDs and sensory signals and efficient read-out by downstream 14 networks for improved visual perception. In summary, our results highlight a novel cognitive-15 dependent arithmetic for the interaction of non-visual signals that dominate the activity of occipital 16 cortical networks during goal-oriented behaviors. These findings provide an experimental and 17 theoretical foundation for the study of active visual perception in ethological conditions. 18