We recorded cerebral magnetic fields to electric stimulation of the tongue in 7 healthy adults. The two main deflections of the response peaked around 55 msec (P55m) and 140 msec (N140m). During both of them the magnetic field pattern, determined with a 7- or 24-channel SQUID magnetometer, suggested a dipolar current source. The topography of P55m can be explained by a tangential dipole at the first somatosensory cortex (SI) in the posterior wall of the central sulcus. The equivalent source of N140m is, on average, about 1 cm lateral to the source of P55m. The reported method allows non-invasive determination of the cortical tongue representation area.

Adult↗

PubMedDate not supplied

Ultrawide-band electromagnetic pulses induced hypotension in rats.

The ultrawide-band (UWB) electromagnetic pulses are used as a new modality in radar technology. Biological effects of extremely high peak E-field, fast rise time, ultrashort pulse width, and ultrawide band have not been investigated heretofore due to the lack of animal exposure facilities. A new biological effects database is needed to establish personnel protection guidelines for these new type of radiofrequency radiation. Functional indices of the cardiovascular system (heart rate, systolic, mean, and diastolic pressures) were selected to represent biological end points that may be susceptible to the UWB radiation. A noninvasive tail-cuff photoelectric sensor sphygmomanometer was used. Male Wistar-Kyoto rats were subjected to sham exposure, 0.5-kHz (93 kV/m, 180 ps rise time, 1.00 ns pulse width, whole-body averaged specific absorption rate, SAR = 70 mW/kg) or a 1-kHz (85 kV/m, 200 ps rise time, 1.03 ns pulse width, SAR = 121 mW/kg) UWB fields in a tapered parallel plate GTEM cell for 6 min. Cardiovascular functions were evaluated from 45 min to 4 weeks after exposures. Significant decrease in arterial blood pressures (hypotension) was found. In contrast, heart rate was not altered by these exposures. The UWB radiation-induced hypotension was a robust, consistent, and persistent effect.

Animals↗