Rapid Learning of Magnetic Compass Direction by C57BL/6 Mice in a 4-Armed ‘Plus’ Water Maze

Abstract

Magnetoreception has been demonstrated in all five vertebrate classes. In rodents, nest building experiments have shown the use of magnetic cues by two families of molerats, Siberian hamsters and C57BL/6 mice. However, assays widely used to study rodent spatial cognition (e.g. water maze, radial arm maze) have failed to provide evidence for the use of magnetic cues. Here we show that C57BL/6 mice can learn the magnetic direction of a submerged platform in a 4-armed (plus) water maze. Naïve mice were given two brief training trials. In each trial, a mouse was confined to one arm of the maze with the submerged platform at the outer end in a predetermined alignment relative to magnetic north. Between trials, the training arm and magnetic field were rotated by 180° so that the mouse had to swim in the same magnetic direction to reach the submerged platform. The directional preference of each mouse was tested once in one of four magnetic field alignments by releasing it at the center of the maze with access to all four arms. Equal numbers of responses were obtained from mice tested in the four symmetrical magnetic field alignments. Findings show that two training trials are sufficient for mice to learn the magnetic direction of the submerged platform in a plus water maze. The success of these experiments may be explained by: (1) absence of alternative directional cues (2), rotation of magnetic field alignment, and (3) electromagnetic shielding to minimize radio frequency interference that has been shown to interfere with magnetic compass orientation of birds. These findings confirm that mice have a well-developed magnetic compass, and give further impetus to the question of whether epigeic rodents (e.g., mice and rats) have a photoreceptor-based magnetic compass similar to that found in amphibians and migratory birds.

Polarized light modulates light-dependent magnetic compass orientation in birds

“…Zebra finches trained to relocate a food reward in the spatial orientation assay using directional magnetic compass information learned the task rapidly, in only three to four training trials (Fig. 1B and Table S1) (33). Birds trained to find the reward at either magnetic north (mN) or magnetic south (mS) were significantly oriented along the trained magnetic compass axis when subsequently tested in the presence of a magnetic field aligned in one of four topographic directions [P < 0.05, confidence interval (CI) test; Fig.…”

Zebra finches have a light-dependent magnetic compass similar to migratory birds

“…Animals thus use a light-dependent magnetic compass not only for large-scale migrations but also for small-scale orientation tasks in their familiar environment (e.g. Muheim et al, 2006b;Painter et al, 2013;Phillips et al, 2013; see also Phillips et al, 2010b).…”

High levels of maternally transferred mercury disrupt magnetic responses of snapping turtle hatchlings (Chelydra serpentina)

“…Magnetoreception can be involved in many aspects of spatial behaviour: as a compass for local and long-distance movements (Wiltschko and Wiltschko, 1972;Landler et al, 2015;Phillips et al, 2013;Diego-Rasilla et al, 2010;Dommer et al, 2008;Freake et al, 2002) as a source of geographic position information (i.e., a magnetic map Phillips, 1986;Philips et al, 1995;Deutschlander et al, 2012) as a reference that reduces errors in path integration (Kimchi et al, 2004;Philips et al, 2010) and potentially as a spherical coordinate system that helps to encode the organism's immediate surrounding and to incorporate local landmark arrays into a global map of familiar space (Landler et al, 2015;Phillips et al, 2010). Consequently, loss of a magnetic sense could impact both long-distance movements (e.g.…”