The sensitivity of cognitive processes to the inhomogeneity of natural magnetic fields

Three experiments were carried out to study the influence of inhomogeneity of natural magnetic field (MF) on animal cognition. Wistar rats (n = 90) were placed in a complicated problem environment, in which they were to form food-operant behavior under conditions of natural MF (Cond. 1) and MFs produced by iron objects (Cond. 2) or by magnets (Cond. 3). Unlike the control group (Cond. 1), all rats in Cond. 2 and 3 were unable to form operant behavior. Weak MF caused both locomotor and emotional depression, and there was no exploratory activity shown during 6 sessions. Brief external stimulation removed locomotor depression, and animals formed operant behavior similar to latent learning (Cond. 2) or "insight" (Cond. 3). Performance efficiency was lower while the level of stress manifestation was higher in Cond. 2 and 3 than in the control at the stage of stabilization. It has been proposed that MF reduces the activity of brain motivation centers and prevents the development of complicated forms of cognitive activity.