Brain & Nervous System

Human Telecommunications: A review of the Literature on "Biological Radio Communication" and related topics

C. J. Chilton

НЕКОТОРЫЕ ДАННЫЕ О ДЕЙСТВИИ САНТИМЕТРОВЫХ ВОЛН (Экспериментальные исследования)

З. В. Гордон, Е. А. Лобанова, М. С. Тольская

ASSESSMENT OF THE BIOLOGICAL EFFECTS OF RADIOFREQUENCY RADIATION

Joseph M. Lary, David L. Conover, William E. Murray

The authors reviewed and critically evaluated the radiofrequency biological effects literature through 1982. The review indicated that there appears to be a threshold for adverse biological effects in animals at a specific absorption rate of about 2 W/kg. At SARs between 1.8 and 4.5 W/kg, adverse effects included death, temperature increases exceeding 3%, hemorrhagic lesions, staggering and spasms in chicks, and extreme agitation in dogs. At SARs below 1.8 W/kg no clearly adverse effects were reported, but measurable temperature increases and physiological changes occurred in the 0.17 to 1.8 W/kg range. At SARs below 0.17 W/kg no temperature increases were reported and most effects involved calcium efflux or blood-brain barrier permeability.

A Simplified Analog Storage and Averaging System for Electroencephalographic Responses

John F. Davis et al.

The system records the stimulation series and EEG responses on tape, forms the tape into a loop, and plays it through a gated integrator to plot the averaged response amplitude at selected time points. With recording at 33 ¼ ips and play- back at 15 ips, the analysis proceeds at four times the speed of the original experiment. However, since as many as one hundred points may have to be plotted, the analysis can still run to several hours. At present, the speed ratio is limited to 4:1 by considerations of transient response and information bandwidth.

CDRH CURRENT BIOLOGICAL INTRAMURAL PROJECTS (ELECTROMAGNETIC RADIATION BRANCH, DLS, OST)

Unknown authors

Cardiac and Neural Effects of Radar Wavelengths

Allan H. Frey

MOTOR COORDINATION OR BALANCE DIFFERENCES BETWEEN RATS EXPOSED OR SHAM EXPOSED TO 60 HZ ELECTRICAL FIELDS

Unknown authors

A SYSTEM FOR PRODUCING LOCALIZED HYPERTHERMIA IN BRAIN TUMORS THROUGH MAGNETIC INDUCTION HEATING OF FERROMAGNETIC IMPLANTS

Unknown authors

The researchers are developing a magnetic induction system to produce localized hyperthermia in intracranial tumors. Differential heating is achieved using small ferromagnetic seeds that can be stereotactically embedded in residual tumor during craniotomy. In phantom tests, Trial 16 showed a temperature differential greater than 4°C out to 1 cm from the implant site with no significant direct heating of the phantom by the RF field. Heating patterns in single seed phantoms matched the theoretically expected inverse radial distance dependence.

EFFECT OF CHRONIC EXPOSURE TO AN ELECTRIC FIELD ON SUBSEQUENT DISCRIMINATION OF ELECTRIC FIELDS

Unknown authors

Researchers exposed male Sprague Dawley rats to a 100 kV/m 60-Hz electric field for 30 days at 22 hours per day or gave them sham exposure. After exposure, rats were tested in a shuttlebox with one end shielded and the other exposed at field strengths of 0, 25, 50, 75, or 100 kV/m. Pre-exposed rats spent significantly more time in the exposed region at 25 kV/m than sham pre-exposed controls. Within the pre-exposed group, exposed side residence was higher across field strengths, while sham pre-exposed rats spent more time on the shielded side.

CHANGES IN TEMPORAL ASPECTS OF BEHAVIOR BY LOW LEVELS OF PULSED MICROWAVES

Unknown authors

MODULATION OF PENTOBARBITAL EFFECTS ON TIMING BEHAVIOR IN RATS BY LOW-LEVEL MICROWAVES

Unknown authors

Rats were trained to press a lever on a schedule that rewarded responses spaced 18 to 24 seconds apart. Concurrent 30-minute exposures to 1 mW/cm² or 5 mW/cm² pulsed microwave radiation shifted the maximally effective pentobarbital dose range to 5 to 10 mg/kg. The response mode shifted from 14 to 22 seconds to 10 to 18 seconds, a 25 percent change.

MICROWAVE FEVER: AN ATTEMPT TO TRANSFER STREPTOCOCCAL ANTIBODY ACROSS THE CEREBROSPINAL-FLUID (CSF) BARRIER

Unknown authors

THE EFFECT OF PRENATAL MICROWAVE EXPOSURE ON THE DEVELOPMENT OF BEHAVIORAL RESPONSES IN THE MOUSE

Unknown authors

Pregnant ICR mice were exposed to 2450 MHz continuous-wave radiation for 3 hours daily from gestational day 7 to 17 at an average power density of 10 mW/cm². Pups were tested from day 1 to day 21 postpartum using a battery of behavioral and neurological tests, all conducted blind. Exposed pups showed delayed initiation of several behavioral responses compared with sham-exposed pups. The delay affected the time needed for all exposed pups to achieve each response, but all exposed pups eventually reached the same developmental level as controls.

THERMAL EFFECTS ON COLONIC AND REGIONAL BRAIN TEMPERATURE IN UNANESTHETIZED RATS EXPOSED TO 2450 MHz CW MICROWAVES

Unknown authors

Researchers monitored colonic temperature and temperatures in the cerebral cortex, hypothalamus, cerebellum, and medulla of unanesthetized rats that were either sham-exposed or exposed to 2450 MHz CW microwaves at 65 mW/cm² for 30 or 90 minutes. Regional brain and colonic temperatures were significantly higher in exposed rats than in sham controls after both exposure durations. In sham rats the mean cortical temperature was 36.6°C. After 30 minutes of exposure cortical temperature rose to 40.0°C and after 90 minutes to 42.1°C. Cortical and cerebellar temperatures were slightly lower than colonic temperature, while hypothalamic and medullary temperatures were slightly higher in all groups.

MODIFICATION OF MICROWAVE BIOLOGICAL END-POINTS BY INCREASED RESTING METABOLIC HEAT LOAD IN RATS

Unknown authors

BIOLOGICAL ALTERATIONS OBSERVED UNDER MICROWAVE IRRADIATION

A. DEFICIS, J.C. DUMAS, S. LAURENS

THE EFFECT OF 9.31 GHZ PULSED MICROWAVE IRRADIATION ON THE LEVER PRESS BEHAVIOR OF OPERANTLY RESPONDING RHESUS MONKEYS

Unknown authors

Twelve rhesus macaques were trained to press a lever for apple juice while positioning their heads in front of a 9.311 GHz microwave horn. The microwave delivered a 0.5 μs pulse at an average power density of 150 mW/cm² at the monkey's head. Over 20 sessions of 15 minutes each, with 10 irradiation and 10 non-irradiation sessions, the combined mean lever press rate did not differ significantly. Individual monkeys showed significant differences in lever press rates between irradiation conditions. A transition experiment on 6 monkeys found no statistically significant effect on mean lever press rate when the radiation was switched on or off.

CHRONIC EXPOSURE OF RATS TO 100-MHz (CW): ASSESSMENT OF BIOLOGICAL EFFECTS

Unknown authors

Researchers exposed 20 time-bred rats to 100-MHz RF at 500 W forward power (50 mW/cm²) starting on day 6 of pregnancy for 4 hours per day, 7 days per week. The mean specific absorption rate for rats was 2.8 mW/g. No differences were found in growth, neurological development, locomotor activity, hematology, immune function, or mutagenicity between exposed and sham-exposed rats. However, significant changes in regional brain acetylcholinesterase activities were observed in chronically exposed rats.

THE DIFFERENTIATION (RETRANSFORMATION) OF NEUROBLASTOMA CELLS AS AN INDICATOR OF THE BIOLOGIC ACTIVITY OF PULSED MAGNETIC RADIATION. THE NON-THERMAL EFFECTS OF PULSED ELECTROMAGNETIC FIELDS ON TUMOR GROWTH AND IN VITRO MOUSE PALATAL DEVELOPMENT AND NEUROBLASTOMA DIFFERENTIATION.

Unknown authors

Researchers placed neuroblastoma cells in homogeneous time-varying magnetic fields at 2 gauss average using 4-inch air gap coils. The induced current wave forms at yA/cm² level were designed to excite only surface or surface-coupled transport processes. Significant differences in dendritic outgrowth and surface adhesion versus multiplication were detected as a function of the induced current wave forms. In mice with transplanted Lewis lung tumors, 27 MHz pulsed fields inhibited or accelerated tumor growth depending on timing and pulsed frequencies.

ALTERATION OF REPEATED ACQUISITION IN RATS BY MICROWAVE RADIATION

Unknown authors

Researchers examined the acute effects of pulsed 2800 MHz microwave radiation on repeated acquisition learning in three rats. Rats were exposed for 30 minutes to five power densities (0.25, 0.5, 1.0, 5.0, and 10.0 mW/cm²) before test sessions.

INDUCTION OF CALCIUM ION EFFLUX FROM BRAIN TISSUE BY R.F. RADIATION: EFFECT OF SAMPLE NUMBER AND MODULATION FREQUENCY ON THE FIELD-STRENGTH WINDOW

Unknown authors

TERATOLOGY IN RATS EXPOSED TO 2450 MHZ MICROWAVES AT INTENSE AND INTERMEDIATE DOSE RATES

Unknown authors

Forty dams were exposed to 2450 MHz microwaves at 31 mW/g or 17 mW/g for 20 minutes on gestational days 8, 10, 12, or 14, while eight received sham exposures and eight served as cage controls. In the 31 mW/g group, 30% of implantations were resorbed and 17% of fetuses had abnormalities, compared to lower rates in other groups. Fetal body mass decreased at 31 mW/g, and fetal brain mass was affected by treatment condition and gestational day.

MICROWAVE MODIFICATION OF THERMOREGULATORY BEHAVIOR: THRESHOLD AND SUPRATHRESHOLD EFFECTS

Unknown authors

Adult male squirrel monkeys were restrained in an anechoic chamber and trained to select between 15°C and 55°C air temperatures, then exposed to 2450 MHz CW microwaves at incident power densities from 1 to 22 mW/cm². At 6-8 mW/cm² the monkeys significantly reduced their selected air temperature, a threshold corresponding to a whole-body SAR of 1.1 W/kg. Infrared radiation of equal incident energy did not produce a comparable reduction, suggesting microwaves stimulate internal thermoreceptors while infrared stimulates skin receptors. At 22 mW/cm² the preferred air temperature was lowered by up to 4°C while skin and rectal temperatures remained stable.

DUAL ACTIONS OF MICROWAVES ON SERUM CORTICOSTERONE IN RATS

Unknown authors

Fifty-eight male Long-Evans rats were exposed to 2.45 GHz continuous-wave microwaves for four hours at power densities of 0, 0.1, 1, 10, 25, and 40 mW/cm². Rats exposed to 0.1 and 1 mW/cm² had significantly lower serum corticosterone than sham-exposed rats, while rats exposed to 40 mW/cm² had significantly higher levels, and no changes occurred at 10 and 25 mW/cm². Colonic temperature increased significantly at 10, 25, and 40 mW/cm² but not at lower intensities.

ACUTE MICROWAVE EXPOSURE AND CENTRAL CHOLINERGIC ACTIVITY: PARAMETERS OF RADIATION

H. Lai, A. Horita, A.W. Guy

Researchers exposed rats to continuous-wave or pulsed 2450-MHz microwaves at 0.6 W/kg for 45 minutes in waveguides or anechoic chambers. Frontal cortical choline uptake decreased under all irradiation conditions. Hippocampal choline uptake decreased in animals exposed to pulsed microwaves. Striatal choline uptake decreased after exposure in the miniature anechoic chamber. Hypothalamic choline uptake was not significantly affected.