Motor behavior results in complex exchanges of motor and sensory information across cortical regions. Therefore, fully understanding the cerebral cortex’s role in motor behavior requires a mesoscopic-level description of the cortical regions engaged, their functional interactions, and how these functional interactions change with behavioral state. Mesoscopic Ca2+ imaging through transparent polymer skulls in mice reveals elevated activation of the dorsal cerebral cortex during locomotion. Using the correlations between the time series of Ca2+ fluorescence from 28 regions (nodes) obtained using spatial independent component analysis (sICA), we examined the changes in functional connectivity of the cortex from rest to locomotion with a goal of understanding the changes to the cortical functional state that facilitate locomotion. Both the transitions from rest to locomotion and from locomotion to rest show marked increases in correlation among most nodes. However, once a steady state of continued locomotion is reached, many nodes, including primary motor and somatosensory nodes, show decreases in correlations, while retrosplenial and the most anterior nodes of the secondary motor cortex show increases. These results highlight the changes in functional connectivity in the cerebral cortex, representing a series of changes in the cortical state from rest to locomotion and on return to rest.

No abstract

Opaque screening pigments are a fundamental requisite for preserving resolution in image-forming eyes. Possession of any type of image-forming eye in a transparent, pelagic animal will thus undermine the ability of that animal to be invisible in the water column. Transparent, pelagic animals must therefore deal with the trade-off between the ability to see and the ability of other animals to see them. Stomatopod larvae, like many transparent crustaceans, possess specialized optics in their compound eyes that minimize the volume of the opaque retina. Though the volumes of these retinas are reduced, their opacity remains conspicuous to an observer. The light reflected from structures overlying the retinas of stomatopod crustacean larval eyes, referred to here as eyeshine, is hypothesized to further reduce the visibility of opaque retinas. Blue or green wavelengths of light are most strongly reflected in stomatopod larval eyeshine, suggesting a putative spectral matching to the light environment against which the larval eyes are viewed. We tested the efficacy of stomatopod crustacean larval eyeshine as an ocular camouflaging mechanism by photographing larvae in their natural light environment and analysing the contrast of eyes with the background light. To test for spectral matching between stomatopod larval eyeshine and the background light environment, we characterized the spectrum of eyeshine and calculated its performance using radiometric measurements collected at the time of each photographic series. These results are the first to demonstrate an operative mirror camouflage matched in both spectrum and radiance to the pelagic background light environment.

The polarization of light provides information that is used by many animals for a number of different visually guided behaviours. Several marine species, such as stomatopod crustaceans and cephalopod molluscs, communicate using visual signals that contain polarized information, content that is often part of a more complex multidimensional visual signal. In this work, we investigate the evolution of polarized signals in species of Haptosquilla, a widespread genus of stomatopod, as well as related protosquillids. We present evidence for a pre-existing bias towards horizontally polarized signal content and demonstrate that the properties of the polarization vision system in these animals increase the signal-to-noise ratio of the signal. Combining these results with the increase in efficacy that polarization provides over intensity and hue in a shallow marine environment, we propose a joint framework for the evolution of the polarized form of these complex signals based on both efficacy-driven (proximate) and content-driven (ultimate) selection pressures. KEY WORDS: Stomatopod, Mantis shrimp, Polarization vision, Signal evolution, Sensory bias, Multi-modal signal INTRODUCTIONPolarization sensitivity is a common visual specialization that has evolved in both terrestrial and aquatic animals, and is particularly prevalent in invertebrates (Wehner and Labhart, 2006). On land, many insects use the celestial polarization pattern for navigation (Wehner, 1976;Rossel and Wehner, 1986;Labhart and Meyer, 1999;Dacke et al., 2003), while in the ocean, some crustaceans and cephalopod molluscs use polarization information to detect prey and possibly as a means of conspecific communication (Shashar et al., 1996;Cronin et al., 2003a;Chiou et al., 2007;Mäthger et al., 2009;Cronin et al., 2009;Chiou et al., 2011). In the context of communication, polarization often forms composite signals with other visual dimensions, such as hue and brightness (Cronin et al., 2003a;Cronin et al., 2009).The term polarization is used to define several properties of light. The angle of polarization describes the predominant direction in which the electric field of the light oscillates, while the degree of polarization defines the extent to which waves oscillate at the same angle. Underwater, differential sensitivity to either angle or degree of polarization has several fundamental advantages over other forms of visual information (Cronin et al., 2003a;Cronin et al., 2003b;Cronin et al., 2009;Shashar et al., 2011). For instance, in shallow, clear marine waters, the intensity and spectral composition of the downwelling light can vary dramatically, both as a function of the time of day, and because of environmental factors such as turbidity (Cronin et al., 2014). In such changing conditions, the polarization of light remains more constant than other visual dimensions over short ranges (Waterman, 1954;Cronin, 2001), which renders it a reliable provider of information (Shashar et al., 2011;Johnsen et al., 2011). Previous research in this field has fo...