Biomedical subjects

M A Persinger

Publications and source records attributed to M A Persinger.

At least 19 recordsLinked to original sources

PubMed2000

Pretraining exposure to physiologically patterned electromagnetic stimulation attenuates fear-conditioned analgesia.

The effect of weak electromagnetic stimulation on the emergence of conditioned analgesia was examined in the adult rat. Subjects were conditioned to associate a continuous 20 kHz ultrasonic tone (CS) with 0.2 mA footshock (UCS-) over five successive days. For 30 min either before or after conditioning sessions, rats were exposed to sham or pulsed (primed burst potentiation) magnetic fields (500 nT). At the end of the conditioning phase, all animals were evaluated for anticipatory analgesia following CS presentation using a hotplate analgesiometer. Data analysis suggested a statistically significant attenuation of fear-conditioned analgesia in rats exposed to electromagnetic stimulation prior to conditioning, whereas post-conditioning exposure potentiated the reduction in pain sensitivity compared to baseline measures. The present results suggest that the emergence of fear-conditioned responses is sensitive to whole body exposure to a magnetic field pattern that has been shown to induce long-term potentiation in hippocampal slices.

Analgesia↗

PubMed2000

Suppression of experimental allergic encephalomyelitis in rats exposed nocturnally to magnetic fields.

After inoculation with spinal cord and complete Freund's adjuvant, female Lewis rats were exposed to weak, 7 Hz complex magnetic fields or to the control condition. The computer-generated magnetic field, whose amplitude varied from 15 nT to 60 nT every 6 to 12 sec, was presented for 6 min every hour between midnight and 0800 of the scotophase. In two replicates of the experiment, the rats exposed to the field displayed statistically significant suppression relative to sham-field controls (effect size = 55%) of the overt symptoms of experimental allergic encephalomyelitis which included hindleg paralyses.

Animals↗

PubMed1999

Infiltration of lymphocytes in the limbic brain following stimulation of subclinical cellular immunity and low dosages of lithium and a cholinergic agent.

This experiment was designed to investigate the hypothesis that single small dosages of lithium (1.5 mEq/kg), the muscarinic agent pilocarpine (15 mg/kg) and spinal cord emulsion encourage perivascular infiltration of lymphocytes into the brain even when overt symptoms of experimental allergic encephalomyelitis are not apparent. The brains of rats that had received this small dosage of lithium and pilocarpine exhibited discernable infiltrations of lymphocytes within limbic tracts but no discernable neuronal loss. Although the brains of the rats that displayed overt seizures following larger dosages of lithium (3 mEq/kg) and pilocarpine (30 mg/kg) exhibited the usual pattern of neuronal loss within multiple thalamic and limbic structures and conspicuous foci of lymphocytic infiltration (particularly within the hippocampal formation) the correlation between the numbers of foci and the proportions of neuronal damage in these structures was not significant statistically. These results indicate that infiltrations of lymphocytes into brain parenchyma are not simple artifacts of the amount of neuronal damage and may be sensitive toxicological markers for subclinical interactions between drugs and immune responses.

Animals↗

PubMed1999

Subjective time estimation by humans is increased by counterclockwise but not clockwise circumcerebral rotations of phase-shifting magnetic pulses in the horizontal plane.

Volunteers were required to estimate 10-s intervals after 2.5 min exposures to each of six different patterns of complex magnetic fields. The approximately 10 microT fields were applied sequentially through eight solenoids that were arranged circumcerebrally (every 45 deg) at the level of the temporoorbital plane. There were three rates of change for the circumcerebral rotations whose durations ranged between about 200 and 2000 ms. Successive additions of 20 ms of the complex fields during the counterclockwise circumcerebral rotation at each solenoid distended subjective time most effectively. Subjective time of the group who received these counterclockwise rotations was about 3 s longer than the group who received the clockwise rotations (explaining approximately 50% of the variance). The results are consistent with the model that the temporal binding for experience, most likely a feature of the rostrocaudal waves recreated every approximately 20 ms over the cerebral cortices, can be modified by weak magnetic fields whose spatial direction and temporal complexity are designed to interact with this process.

Adult↗

PubMed1999

Increased emergence of alpha activity over the left but not the right temporal lobe within a dark acoustic chamber: differential response of the left but not the right hemisphere to transcerebral magnetic fields.

The percentages of alpha activity per minute over the left and right temporal lobes were measured for the first and second successive 15-min intervals while subjects wore opaque goggles within an acoustic chamber. A weak (5 microT), burst-firing magnetic field was presented during this period for 1 s every 4 s primarily over the left or the right cerebral hemisphere. The results indicated that the left temporal lobe became less vigilant between the first and second 15 min while the right temporal lobe did not. When standardized scores for each subject's measures over time and across hemispheres were employed, increased alpha time over the left temporal lobe relative to the right temporal lobe was observed only when the transcerebral magnetic field was applied over the left hemisphere. Stimulation of the right hemisphere did not evoke this discrepancy. The detection of the effects of this specific complex magnetic field upon electroencephalographic activity may be more probable when the subjects are exposed to partial sensory deprivation.

Adult↗

PubMed1999

Geophysical variables and behavior: LXXXV. Sudden infant death, bands of geomagnetic activity, and pc1 (0.2 to 5 HZ) geomagnetic micropulsations.

Pc1s (continuous pulsations) within the geomagnetic field, whose durations are about 30 minutes but which can reoccur several times nightly, are observed during periods when global geomagnetic activity is very low (less than 10 nT). The hypothesis that these 0.2 to 5 Hz synchronized micropulsations or hydromagnetic emissions might stimulate physical chemical cascades within the brain that precipitate the sudden death in infants was tested by correlational analysis for a two-year period (1960-1961) for Ontario. Results were consistent with the hypothesis that the monthly incidences of these unexpected deaths, pcl micropulsations and geomagnetic activity less than 10 nT displayed a shared source of variance. Implications are discussed.

California↗

PubMed1999

Background sound pressure fluctuations (5 DB) from overhead ventilation systems increase subjective fatigue of university students during three-hour lectures.

During each of four successive sessions (once per week), 21 university students attended 3-hr. lectures. During alternative weeks the fans of the room's ventilation system were either on or off. When operating, they generated an average sound pressure that varied continuously between 60 and 65 dB. The dominant frequency of this 5-dB amplitude modulation of sound pressure was within the electroencephalographic range (5 Hz to 25 Hz). At the end of each hour of the lecture for each session each student estimated on 7-point summated rating scales fatigue (none to maximum) and concentration (poor to excellent). As a group, the students reported more fatigue during lectures when the fans were operating relative to lectures when the fans were not operating. This environmental effect explained about 30% of the variance in fatigue ratings and may be sufficient to affect adversely the attention of students within these settings.

Adult↗

PubMed1999

Geophysical variables and behavior: LXXXVI. Geomagnetic activity as a partial parturitional trigger--are male babies more affected than female babies?

The birth dates of 163 men and 245 women who were born between the years 1958 and 1969 were extracted from our data base for first-year university students. Daily aa values, measures of the amplitude of global geomagnetic activity, were obtained for the birthdays and for each of the seven days before and after the birthdays. Analyses of variance indicated no significant differences in the magnitudes of the geomagnetic activity during these 15 days; however, men were born when the geomagnetic activity was significantly higher than when the women were born. The effect, which was equivalent to a correlation coefficient of about .20, was largest for the day of birth and for the two or three days before birth. The means of the aa values for the day of birth and the day before birth for the men were about 7 nanoTesla higher than the values for the women.

Adult↗

PubMed1999

On the nature of space-time in the observation of physical events in science.

All sciences contain words that define events or aggregates of events from which new properties emerge. There are also words for processes. They require sequential increments of time to be perceived. Systematic relationships exist between the increments of space (meters) and the increments of time (seconds) required to perceive a phenomenon. These relationships suggest that at the largest increment of space, the universe, the processes cannot be perceived. The measurement of femtometer (10(-15) m) and attometer (10(-18) m) space by millisecond increments (human perception) allows temporal and spatial increments to be nested into higher order organizations. Whether or not these systematic relationships between the increments of space and time required to perceive a phenomenon and the similarity of fundamental operations relating events and processes that occurs across the sciences imply an externally structured order or simply reflect the fundamental organization of all human brains is discussed.

Awareness↗

PubMed1999

Wars and increased solar-geomagnetic activity: aggression or change in intraspecies dominance?

Human beings are extremely aggressive animals who are emersed within a steady-state geomagnetic field. A small component of this field displays periodic changes in amplitude. Symmetrical lag/lead analysis (-6 years to +6 years) in the present study, involving annual global geomagnetic activity, inferences of solar activity, and the release of the total, global seismic energy indicated that the numbers of armed conflicts (wars) for the first half of the twentieth century were moderately associated (rs approximately .50; 25% of the variance) only with the global geomagnetic activity of the same year. When the residuals between the predicted annual geomagnetic activity from the solar cycle and the observed geomagnetic activity were allowed to enter the equations, a comparable proportion of the variance in numbers of wars was accommodated. A factor associated with geomagnetic activity might, it is speculated, modulate changes within emergent processes that control the relative dominance of large aggregates of humans. Wars may have been the more obvious manifestations of these changes.

Aggression↗

PubMed1998

Perinatal exposures to rotating magnetic fields 'demasculinize' neuronal density in the medial preoptic nucleus of male rats.

Pregnant rats were exposed continuously for 3 days before to 3 days after birth to 0.5 rotating magnetic fields (RMF) whose intensities ranged between 1.5 and 3.0 mT or between 50 and 300 microT or to sham field conditions. When the male and female rats exposed to these perinatal conditions were about 100 days old, the numbers of neuronal soma and the numbers of nuclei for the three major types of glial cells were counted within the medial preoptic nucleus (MPO), suprachiasmatic nucleus (SCN) and ventromedial nucleus (VMH) of the hypothalamus. The male rats but not the female rats that had been exposed to either intensity of the RMF showed a significant reduction (similar to normal females) in the numbers of neurons within the MPO; the differences accommodated one-third of the variance and were not reduced significantly when the cell densities of the VMH or SCN were covaried before the analyses. The results suggest that some sexually dimorphic structures may be permanently and differentially affected when exposed perinatally to relatively weak extremely low frequency magnetic fields.

Analysis of Variance↗

PubMed1998

Elevations of complex partial epileptic-like experiences during increased geomagnetic activity for women reporting "premenstrual syndrome".

Responses to the frequency of complex partial epileptic-like experiences were recorded every second day by 12 women for at least two months per individual. Five (41%) of the women displayed significant increases (effect sizes between 6% and 17%) in the numbers of these experiences when the daily geomagnetic activity exceeded 40 nT. The results were consistent with the hypothesis that a spectrum of experiences and behaviours, associated with limbic lability, can be enhanced by environmental stimuli correlated with perturbations of the geomagnetic field.

Adult↗

PubMed1998

Test-retest scores for patients who display neuropsychological impairment following "mild head injuries" from mechanical impacts.

A total of 20 patients who had sustained of significant mechanical energies to the skull (> 40 km/hour) were assessed at Time 1, about one year (68% between 2 mo. and 12 mo.) postincident while Time 2 was about two years later. During Time 1 this group was impaired (proficiency z < -2.00) according to two standardized neuropsychological indices and exhibited abnormally elevated psychometric depression (z > 2.00). There were no statistically significant improvements for the scores between Times 1 and 2 on the Halstead-Reitan Impairment Index, the Memory Quotient, Depression, or an impairment index composed of standardized scores for 31 neuropsychological tests. These results indicated that the presumption of some neuropsychologists that patients with "mild head injury" have fully recovered within one year or will continue to improve after about one year following the incident may not be valid for all patients who sustain such brain trauma.

Accidents, Traffic↗

PubMed1998

Persistent elevation of nocturnal activity in rodents following apparent recovery from lithium/pilocarpine-induced limbic seizures.

The nocturnal and day-time activity of rats was monitored continuously after the induction of seizures by a single systemic injection of lithium followed 4 hr. later by the muscarinic agent pilocarpine. Although there was a transient increase in activity during the day cycle shortly after the seizure induction, this behavior returned to baseline levels; however, nocturnal activity increased and remained elevated two or three times above the baseline levels. Implications for the enhancement of nocturnal melatonin levels within the brains of these chronically epileptic rats are discussed.

Animals↗

PubMed1998

Ontogeny of two-point discrimination for fingers and toes in children (ages 7 through 15 years).

Accuracies of two-point discrimination (successive 2-min increments between 0 and 10 mm) for the middle fingers and the middle toes for 87 children from ages 7 through 15 years were measured to obtain normative data. The finer discriminative capacity for the fingers rather than the toes was evident. Whereas discriminative accuracy approached the asymptote with distances equal to or greater than 4 mm for the fingers, distances equal to or greater than 8 mm were required for the toes. For this ontogenetic range, the effects for toes vs fingers was much greater than the effect size for age.

Adolescent↗

PubMed1998

"Subclinical" dosages of lithium and pilocarpine that do not evoke overt seizures affect long-term spatial memory but not learning in rats.

After training is an automated radial maze, 11 male rats were injected with either "subclinical" dosages of lithium and pilocarpine or saline and then tested 5 days or 4 months later. When employed as their own controls or when compared with a saline-injected reference group, the rats that had received the lithium and pilocarpine displayed memory deficits but not learning learning deficits after the longest of the two delays (effect size was 41%). These results suggest that subtle disruption in memory but not learning to criterion could be associated with "subclinical electrical seizures" or the micromorphological changes associated with this activity.

Animals↗

PubMed1998

Geophysical variables and behavior: LXXXIV. Quantitative increases in group aggression in male epileptic rats during increases in geomagnetic activity.

Over a 24-day period the magnitude of the average, 24 hr., global geomagnetic activity was significantly correlated (r and rho about .40) with the average numbers of agonistic (biting) responses between midnight and 0100 hr. in a group of four males epileptic rats. Geomagnetic activity was not significantly correlated with quantitative measures of boxing, mounting, eating, grooming, or drinking. Partial correlations, which also controlled for a weak serial correlation, indicated that the index of geomagnetic activity was only associated with the biting (partial r = .54) behaviors. The results replicated previous studies and suggest that the relationship between aggression and geomagnetic activity is specific and not an artifact of a generalized increase in multiple domains of behavior.

Aggression↗

PubMed1998

Numbers of details in the reconstruction of an emotional narrative decrease linearly as a function of time.

33 university students listened to a 5-min. ambiguous narrative about a young boy (The Billy Story) while another 33 students did not. At the end of the final examination for the course the students were promised a 2% bonus mark if they could reconstruct the details of the story. Whereas only one student who heard the story could not recall any details, 30% of the students (n = 9) who never heard the story generated a false one. The numbers of accurate details recalled by those who heard the story decreased linearly with the time (5 through 30 days). Five times the numbers of the women than men who heard the story attributed the young boy's anomalous experience to sexual abuse.

Adult↗