Virtual reality systems for rodents

Abstract

Over the last decade virtual reality (VR) setups for rodents have been developed and utilized to investigate the neural foundations of behavior. Such VR systems became very popular since they allow the use of state-of-the-art techniques to measure neural activity in behaving rodents that cannot be easily used with classical behavior setups. Here, we provide an overview of rodent VR technologies and review recent results from related research. We discuss commonalities and differences as well as merits and issues of different approaches. A special focus is given to experimental (behavioral) paradigms in use. Finally we comment on possible use cases that may further exploit the potential of VR in rodent research and hence inspire future studies.

Keywords: behavioral neuroscience; closed loop; multisensory stimulation; neural coding; sensorimotor integration; spatial navigation..

Figure 1.

VR setups for rodents. (A) General components of rodent VR setups include a device to restrain and track the animal’s movement, and equipment to provide sensory stimulation. Here, a system is depicted which comprises a spherical treadmill, fixation permitting free rotation of the animal around its vertical body axis, and projection of a visual VR onto a projection screen (cf. Thurley et al. 2014). (B–F) Types of restraints used in rodent VR systems. See main text for details.

Figure 2.

VRs utilizing nonvisual information. (A) Tactile virtual setup simulating running along corridors with/without turns. Distances of movable walls from whisker pads provide information on whether a turn in the corridor is reached. Mice follow these turns reliably even in the absence of prior training (B). Pictures in (A, B) from Sofroniew et al. (2014). (C) An alternative tactile VE, simulating a free walk along a wall in the dark. Mice are head restrained on a linear treadmill and textures are presented on rotating cylinders in reach of the whiskers. (D) Illustration of a simulated “walk along a wall” in a typical closed-loop trial. (E) This experimental setting allows to manipulate the speed of the texture independent from the speed of the animal on the treadmill, permitting closed-loop (animal and texture speed are coupled) as well as open-loop (decoupled) conditions. Brief perturbations, where texture rotation is stopped, are introduced during closed loop and replayed during open-loop trials. (F) Flat-floored air-lifted platform. A head-fixed mouse moves around in an air-lifted mobile cage (orange), which can be enriched with different visual, tactile, and olfactory cues. Picture from Kislin et al. (2014). (G) Open field arena for the virtual water maze task used in the study of Cushman et al. (2013). The movement of the animal is restricted to the central disc. Distal visual and acoustic cues are present in the surrounding. Hidden reward zone and 4 start locations are indicated by the small gray disc and arrows, respectively. In addition to the visual cues, ambisonic auditory stimuli can be provided from speakers surrounding the arena. Picture from Cushman et al. (2013).

Figure 3.

VEs and tasks. (A) VE with a regular field of pillars suspended from the ceiling as used by Hölscher et al. (2005); picture courtesy of Hansjürgen Dahmen. (B) Virtual tracks of different complexity from Thurley et al. (2014). (C) Y-shaped maze to probe decisions in 2 alternative forced choice (2AFC) tasks (picture from Garbers et al. 2015). (D) Above view of the T-shaped virtual maze (modified from Harvey et al. 2012, courtesy of Christopher Harvey). The rewarded arm of the T-maze (marked with red asterisks on the left) is cued on each trial by the color of the track and the position of an external landmark (cf. right panels). (E) Spatiotemporal bisection task used by Kautzky and Thurley (2016).