Precession slope is lower in absolute value in VR than in R (n?=?38, t(37)=-2.19, p 0.05). increases in firing rates with running velocity and place and grid cells’ theta phase precession were comparable. These results suggest that the omni-directional place cell firing in R may require local-cues unavailable in VR, and that PF-4618433 the level of grid and place cell firing patterns, and theta frequency, reflect translational motion inferred from both virtual (visual and proprioceptive) and actual (vestibular translation and extra-maze) cues. By contrast, firing rates and theta phase precession appear to reflect visual and proprioceptive cues alone. strong class=”kwd-title” Research organism: Mouse Introduction Virtual fact (VR) offers a powerful tool for investigating spatial cognition, allowing experimental control and environmental manipulations that are impossible in the real world. For example, uncontrolled real-world cues cannot contribute to determining location within the virtual environment, while the relative influences of motoric movement signals and visual environmental signals can be assessed by decoupling one from your other (Tcheang et al., 2011; Chen et al., 2013). In addition, the ability to study (virtual) spatial navigation in head-fixed mice allows the use of intracellular recording and two photon microscopy (Dombeck et al., 2010; Harvey et al., 2009; Royer et al., 2012; Domnisoru et al., 2013; Schmidt-Hieber and H?usser, 2013; Heys et al., 2014; Low et al., 2014; Villette et al., 2015; Danielson et al., 2016; Cohen et al., 2017). However, the utility of these approaches depends on the extent to which the neural processes in question can be instantiated within the virtual reality (for a recent example of this argument observe Minderer et al., ). The modulation of firing of place cells or grid cells along a single dimension, such as distance travelled along a specific trajectory or path, can be observed as virtual environments are explored by head-fixed mice (Chen et al., 2013; Dombeck et al., 2010; Harvey et al., PF-4618433 2009; Domnisoru et al., 2013; Schmidt-Hieber and H?usser, 2013; Heys et al., 2014; Low et al., 2014; Cohen et al., 2017) or body-fixed rats (Ravassard et al., 2013; Acharya et al., 2016; Aghajan et al., 2015). However, the two-dimensional firing patterns of place, grid and head-direction cells in real-world open arenas are not seen in these systems, in which the animal cannot actually rotate through 360. By contrast, the two-dimensional (2-d) spatial firing patterns of place, head direction, grid and border cells have been observed in VR systems in which rats can actually rotate through 360(Aronov and Tank, 2014; H?lscher et al., 2005). Minor differences with free exploration remain, for?example the frequency of the movement-related theta rhythm is reduced (Aronov and Tank, 2014), perhaps due to the absence of translational vestibular acceleration signals (Ravassard et al., 2013; Russell et al., 2006). However, the coding of 2-d space by neuronal firing can clearly be analyzed. These VR systems constrain a rat to run on top of an air-suspended Styrofoam ball, wearing a jacket attached to a jointed arm on a pivot. This allows the rat to run in any direction, its head is free to look around while its body is maintained over the centre of the ball. These 2-d VR systems maintain a disadvantage of the real-world freely moving paradigm in that the head movement precludes use with multi-photon microscopy. In addition, some training is required for rodents to tolerate wearing a jacket. Here, we present a VR system for mice in which a chronically implanted head-plate enables use of a holder that constrains head movements to rotations in the horizontal plane while the animal runs on a Styrofoam ball. Screens and projectors project a virtual environment in all horizontal directions round the mouse, and onto the floor below it, from a viewpoint that moves with the rotation of the ball, following Aronov and Tank (2014) and H?lscher et al. (2005) (observe Physique 1 and Materials and methods). Open in a separate window Physique 1. Virtual fact setup and behavior within it.(A) Schematic of the VR setup (VR square). (B) A rotating head-holder. (C) A mouse attached to the head-holder. (DCE) Side views of the PF-4618433 VR environment. (FCG) Average running speeds of all trained mice PF-4618433 (n?=?11) across training trials in real (R; F) and virtual fact (VR; G) environments in the main experiment. (H) Comparisons of the average running speeds between the first Rabbit Polyclonal to H-NUC five trials and the last five trials in both VR and R environments, showing a significant increase in both (n?=?11, p 0.001, F(1,10)=40.11). (ICJ) Average Rayleigh vector lengths of running direction across training trials in R (I) and VR (J). (K) Comparisons of the average Rayleigh vector lengths of running direction between the first five trials and the last five trials in both VR and R. Directionality was marginally.