Revaluation of magnetic properties of Magneto, MagR and αGFP−TRPV1/GFP−ferritin

ABSTRACT AND INTRODUCTION Magnetic control of neuronal activity offers many obvious advantages over electric, optogenetic and chemogenetic manipulations. A recent series of highly visible papers reported the development of magnetic actuators (i.e., Magneto, MagR and αGFP−TRPV1/GFP−ferritin) that appeared to be effective in controlling neuronal firing 1–3 , yet their action mechanisms seem to conflict with the principles of physics 4 . We found that neurons expressing Magneto, MagR and αGFP−TRPV1/GFP−ferritin did not respond to magnetic stimuli with any membrane depolarization (let alone action potential firing), although these neurons frequently generated spontaneous action potentials. Because the previous study did not establish the precise temporal correlation between magnetic stimuli and action potentials in recorded neurons 1–3 , the reported magnetically-evoked action potentials are likely to represent mismatched spontaneous firings.