A touchscreen based global motion perception task for mice

Abstract

Global motion perception is a function of higher, or extrastriate, visual system circuitry. These circuits can be engaged in visually driven navigation, a behavior at which mice are adept. However, the properties of global motion perception in mice are unclear. Therefore, we developed a touchscreen-based, two-alternative forced choice (2AFC) task to explore global motion detection in mice using random dot kinematograms (RDK). Performance data was used to compute coherence thresholds for global motion perception. The touchscreen-based task allowed for parallel training and testing with multiple chambers and minimal experimenter intervention with mice performing hundreds of trials per session. Parameters of the random dot kinematograms, including dot size, lifetime, and speed, were tested. Mice learned to discriminate kinematograms whose median motion direction differed by 90 degrees in 7-24 days after a 10-14 day pre-training period. The average coherence threshold (measured at 70% correct) in mice for this task was 22 ± 5%, with a dot diameter of 3.88 mm and speed of 58.2 mm/second. Our results confirm the ability of mice to perform global motion discriminations, and the touchscreen assay provides a flexible, automated, and relatively high throughput method with which to probe complex visual function in mice.

A Role for Mouse Primary Visual Cortex in Motion Perception

“…The coherence threshold measured in our task agrees with measurements in freely-moving mice [18,19], with 75% correct choices when viewing 40% coherent stimuli (Figure 2A), indicating that performance does not seem to be significantly compromised by head restraining the animals. In previous reports using freely moving discrimination tasks, mice only discriminated between RDKs moving along different axes[17,18], one of the studies reporting that mice could not be trained to discriminate stimuli moving in opposing directions[17]. Our study shows that mice can robustly discriminate motion stimuli moving in opposing directions along the horizontal axis both in monocular (Figures 1 and 2) and binocular visual fields (Figure S4).…”

“…Since our task is head-fixed, it allows for excellent stimulus control and repeatability across trials while facilitating neuronal manipulations and recordings of large neuronal populations and subcellular compartments[5,47]. The coherence threshold measured in our task agrees with measurements in freely-moving mice [18,19], with 75% correct choices when viewing 40% coherent stimuli (Figure 2A), indicating that performance does not seem to be significantly compromised by head restraining the animals. In previous reports using freely moving discrimination tasks, mice only discriminated between RDKs moving along different axes[17,18], one of the studies reporting that mice could not be trained to discriminate stimuli moving in opposing directions[17].…”

“…The motion discrimination task provides a unique assay for dissecting retino-forebrain and retino-midbrain circuits involved in motion processing as it involves stimuli engaging On-Off DSGCs and depends on a functioning visual cortex. Previous behavioral paradigms using operant conditioning for assessing motion vision in mice involved freely moving tasks[17,18]. Since our task is head-fixed, it allows for excellent stimulus control and repeatability across trials while facilitating neuronal manipulations and recordings of large neuronal populations and subcellular compartments[5,47].…”

“…Previously, visual acuity in mice has been assessed with reflexive behaviors such as the optokinetic reflex, a behavior involving subcortical structures and not requiring a functional visual cortex [15,16]. Alternatively, motion vision has been probed using operant behavioral methods in freely moving mice[17,18]. However, there are no known motion discrimination tasks in mice with a demonstrated dependence upon primary visual cortex.…”

Flow stimuli reveal ecologically-appropriate responses in mouse visual cortex

“…We show here that ecologically-relevant stimuli can exercise mouse visual cortex in novel and manifold ways. While plaids [13,14] and random-dot kinematograms [15,16] are a step beyond gratings, the leap to natural images (e.g., [17]) is more common (e.g., [18,19]). However, natural images are difficult to obtain [20], difficult to control parametrically, and difficult to analyze beyond second-order [21].…”