Effects of Prolonged Exposure to a Constant Electric Field on the Brain in Rats

An experimental paradigm consisting of prolonged transcranial stimulation of the human brain with a constant electric field was modeled in living rat hippocampal slices. Exposure to electric fields (14 min, 250 mV/mm) in the anodal and cathodal directions led to statistically significant changes in the amplitudes of total response (pop spikes) to stimulation of Schaffer collaterals (1/30 sec) in field CA1, with increases and decreases respectively. No long-term stimulation aftereffects were seen. Blockade of NMDA receptors with MK-801 eliminated electric field effects and induced a gradual decrease in responses throughout the recording period. It is suggested that the decrease in responses may reflect transfer of synapses to the “silent” state.