A physical mechanism of magnetoreception: Extension and analysis.

Proposed is a general physical mechanism of magnetoreception of weak magnetic fields (MFs). The mechanism is based on classical precessional dynamics of a magnetic moment in a thermally disturbed environment and includes a minimum of necessary parameters-the gyromagnetic ratio, thermal relaxation time, and rate of downstream events generated by changes in the state of the magnetic moment. The mechanism imposes general restrictions on the probability of initial biophysical magnetic transduction event before the involvement of specific biophysical and biochemical mechanisms-i.e., regardless of the nature of an MF target and the subsequent cascade of events. It is shown that biological effects of weak MFs have, in certain cases, nonlinear and frequency selective properties. The observation of these characteristics provides information not only on the target's gyromagnetic ratio, but also on the parameters of its interaction with the immediate environment. This enables one to develop experimental strategies for identifying the biophysical mechanisms of magnetoreception including the specific case of effects of a near-zero MF exposure. The mechanism is universally applicable to magnetic moments of different nature, in particular, of electron and proton orbital motion and of spins. Experimental exposure conditions are derived which would lead to validation of the proposed mechanism. Bioelectromagnetics. 38:41-52, 2017.