Influence of a complex magnetic field application in rats upon thermal nociceptive thresholds: the importance of polarity and timing.
The application of a weak (1 microTesla) complex magnetic field pattern with a relevant electrophysiological signature produced an analgesic response in rats to thermal stimuli when the pattern was presented once every 4 sec for 30 min through iron-core solenoids. In one experiment, the burst-firing pattern was presented once every 4 s for 30 min and restricted to the positive polarity, negative polarity or a bipolar equivalent. The strongest analgesia occurred when the burst-firing pattern was presented with positive polarity or as the typical bipolar signal. Administrations of the burst-firing pattern once per week for four consecutive weeks produced analgesia that was clearly evident during the first, third, and fourth weeks but not during the second week of treatment. A telephone sensor coil (that can be readily obtained from local electronic shops) was then used instead of the solenoids along with an audio (.wav) file to generate the magnetic field; the analgesia was still apparent. However, when the magnetic pattern was generated from a compact disc source the analgesia was not evoked. The current results suggest that these fields can be generated through simple commercial devices controlled by available computer software.
Martin
L J
LJ
Behavioral Neuroscience Laboratory, Laurentian University, Sudbury, Ontario, Canada.
Koren
S A
SA
Persinger
M A
MA
D000818:Animals; D004307:Dose-Response Relationship, Radiation; D004566:Electrodes; D004574:Electromagnetic Fields; D006930:Hyperalgesia / Q000628:therapy*; D008297:Male; D008422:Materials Testing; D010147:Pain Measurement; D017288:Pain Threshold / Q000528:radiation effects*; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time / Q000528:radiation effects; D013997:Time Factors