Since many of these tasks, such as face recognition and image seg

Since many of these tasks, such as face recognition and image segmentation, are still challenging for computer algorithms, there is great interest in investigating how the brain implements these high-level computations. Recently, the mouse has emerged as

a powerful model system for studying vision. A primary drive behind this is the development of a wide array of genetic tools to both analyze connectivity and control activity in neural circuits (Luo et al., 2008), along with the experimental accessibility for recording and manipulation relative to human and nonhuman primates. On the other hand, the fact that the mouse is a nocturnal species with relatively low acuity raises the possibility that its visual system could be missing important aspects of vision studied in primates. However, a number of recent studies, from the retina up to V1, have demonstrated that most, though not all, basic properties of visual function are present in the mouse (Huberman and Niell, 2011). These observations open the door to using the new genetic tools available in mouse to address fundamental questions about how neural

circuits process visual information. Until now, primary visual cortex has been the farthest station along the visual pathway to be intensively studied in the mouse at the level of individual neurons. In Tyrosine Kinase Inhibitor Library nmr this issue of Neuron, two groups report initial forays into mouse extrastriate cortex ( Andermann et al., 2011 and Marshel et al., 2011), armed with novel optical methods that allow them to identify and record from the various cortical areas. The two studies are complementary for in many ways. Marshel et al. provide a detailed functional map of the layout of nine extrastriate areas in the anesthetized mouse and show that among a subset of six of these, each region has a unique signature of spatiotemporal tuning.

On the other hand, Andermann et al. studied awake mice and concentrated more closely on two particular regions suggested to be part of the dorsal stream, finding that each is differently specialized for motion processing. A tantalizing glimpse of this uncharted territory beyond V1 had previously been provided by mapping and anatomical studies from Andreas Burkhalter and colleagues (Wang and Burkhalter, 2007 and Wang et al., 2011). These studies demonstrated that the region around V1 contains a number of cortical areas each encompassing its own mapped representation of visual space (Figure 1B), much as seen in monkeys and humans. Furthermore, the connectivity of these regions suggested a homology with the dorsal and ventral pathways in the primate cortex. In contrast to primates, where visual cortex spans centimeters, the entirety of extrastriate cortex in the mouse spans less than five millimeters, with some areas only a few hundred microns across.

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