© 2015 Elsevier Ltd. Spanning about 9mm2 of the posterior cortex surface, the mouse's small but organized visual cortex has recently gained attention for its surprising sophistication and experimental tractability [1-3]. Though it lacks the highly ordered orientation columns of primates [4], mouse visual cortex is organized retinotopically [5] and contains at least ten extrastriate areas that likely integrate more complex visual features via dorsal and ventral streams of processing [6-14]. Extending our understanding of visual perception to the mouse model is justified by the evolving ability to interrogate specific neural circuits using genetic and molecular techniques [15, 16]. In order to probe the functional properties of the putative mouse dorsal stream, we used moving plaids, which demonstrate differences between cells that identify local motion (component cells) and those that integrate global motion of the plaid (pattern cells; Figure1A; [17]). In primates, there are sparse pattern cell responses in primate V1 [18, 19], but many more in higher-order regions; 25%-30% of cells in MT [17] and 40%-60% in MST [20] are pattern direction selective. We present evidence that mice have small numbers of pattern cells in areas LM and RL, while V1, AL, and AM are largely component-like. Although the proportion of pattern cells is smaller in mouse visual cortex than in primate MT, this study provides evidence that the organization of the mouse visual system shares important similarities to that of primates and opens the possibility of using mice to probe motion computation mechanisms. Juavinett etal. expand on the growing interest of the mouse as a model for visual neuroscience, demonstrating that cells in two areas of mouse visual cortex can compute the global motion of a plaid. The report of these pattern direction cells in areas LM and RL, but not V1, AL, or AM, further delineates dorsal and ventral streams in the mouse.
