Biomedical subjects

M A Persinger

Publications and source records attributed to M A Persinger.

At least 127 records · Page 7Linked to original sources

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↗

PubMed1998

Anticipatory cues can interfere with inhibitory operant behavior in the rat.

In four separate experiments a total of 24 male rats were trained for 30 min. daily in the same temporal order to inhibit their responses for at least 6 sec. before a response-contingent reward was delivered (DRL-6 sec.). The rats tested as the second group each day displayed about twice the number of errors (effect size = 40%) shown by rats tested in the first or third groups. These results suggest that anticipatory cues, acquired within two sessions, interfere with response inhibition during an appetitive task for a limited time (between a few minutes to about one hour). The results are consistent with the hypothesis that learned anticipation of reward may decrease inhibitory mechanisms by facilitating limbic lability.

Animals↗

PubMed1998

SPECT (HMPAO) support for activation of the medial prefrontal cortices during toe graphaesthesia.

This experiment was designed to test the construct validity of psychometric analyses that suggested a strong functional association between the accuracy for toe graphaesthesia and selective activation of neurons within the medial prefrontal regions. Single Photon Emission Computerized Tomography (SPECT) profiles were obtained for three volunteers (2 men, 1 woman) after they had been exposed to a toe graphaesthesia task or had been exposed to the control setting. The two measurements for each participant were separated by at least one week. Qualitative evaluation, using criteria employed for clinical diagnoses, of serial coronal, sagittal, and horizontal sections clearly indicated a specific increase in uptake of tracer within the rostral one-third to one-half of the medial prefrontal cortices of all three subjects during the toe graphaesthesia task compared to that during baseline conditions. The results are consistent with our neuropsychological research which indicates that toe graphaesthesia may be an accurate and useful indicator of the functional integrity of the medial surfaces of the anterior cerebral hemispheres.

Adult↗

PubMed1998

Hypnotic induction profiles, contextual innuendo, and delayed intrusion errors for a narrative: searching for mediating variables.

18 young men and 18 women listened to an ambiguous narrative concerning the nocturnal experiences of a young boy and then, after an inventory on hypnotic induction and a dichotic word-listening task, were asked to estimate the prevalence of child abuse or abduction by aliens (a third group served as controls). One week later the subjects were asked to reconstruct the narrative. Scores for suggestibility, estimates of prevalence, the sense of a presence during the first sitting and less cerebral lateralization were loaded on the same factor. Although the three groups did not differ with respect to numbers of literal memories, the groups who were given either one of the two innuendos also included an additional 11% of inferences and paraphrases which were considered erroneous reconstructions of the memory of the narrative.

Auditory Perception↗

PubMed1998

Putative perception of rotating permanent magnetic fields following ingestion of LSD.

While sitting alone in complete darkness, 3 participants who had ingested psychotropic concentrations of lysergic acid diethylamide reported diffuse blobs of white, purplish, or greenish-yellow lights as two horseshoe magnets rotated at 0.5 Hz. The experiences were not reported when the magnets were stationary or removed from the apparatus. The estimated peak-to-peak variation in field strength at the distance of perception was between 50 and 500 nanoTesla. An association between these results and possible ergot-induced perceptions of "magnet light" reported during the last century by von Reichenbach (1851) is suggested.

Adult↗

PubMed1998

Ventricular dilation over several weeks following induction of excitotoxic (systemic lithium/pilocarpine) lesions: potential role of damage to the substantia nigra reticulata.

Time-dependent atrophy of cerebral space and enlargement of the lateral ventricles were noted in healthy rats 1 to 100 days after the induction of seizures by a single systemic injection of lithium and pilocarpine. The rate of atrophy was most strongly correlated (0.90) with the log (base 10) of the time in days. Most of the degeneration had occurred within about 20 to 30 days after the seizure-induced brain trauma. Concomitant reduction in the area of the substantia nigra reticulata was the most powerful predictor of ventricular enlargement at the level of the caudate-putamen.

Animals↗

PubMed1998

Experimental induction of intermale aggressive behavior in limbic epileptic rats by weak, complex magnetic fields: implications for geomagnetic activity and the modern habitat?

In three separate experiments, groups (4/group) of male rats with limbic epilepsy were exposed for 80 min every 24 hr during the midscotophase for 24 successive days to sham-field conditions or to one of four complex patterns of magnetic fields whose average intensities ranged between 20 nT to 500 nT. The numbers of episodes of boxing, biting, mounting, eating, drinking and grooming were then recorded each night during the latter 20 min. Moderately strong statistically significant interactions occurred between the presence or absence of the field and the pattern of the field explained 25% and 50% of the variance in the numbers of biting and boxing responses, respectively. Other behaviors were not affected. The results suggest that group aggression can be increased or decreased as a function of the temporal characteristics and morphology (shape) of the applied magnetic field.

Aggression↗

PubMed1997

Experimental simulation of the effects of increased geomagnetic activity upon nocturnal seizures in epileptic rats.

This experiment was designed to simulate experimentally the specific parameters of geomagnetic activity that evoke epileptic seizures. The numbers of overt limbic seizures (rearing, paroxysmal forelimb clonus and falling) in a population of epileptic rats were recorded nightly for 65 successive days between 0200 and 0400 h during red light conditions. On some nights an experimental 7 Hz magnetic field whose magnitudes shifted in successive steps from zero to approximately 50 nT every 3 min was presented. The partial regression coefficients from the analysis indicated that either the presence of the 'synthetic' geomagnetic activity or increased magnitudes of the daily, natural geomagnetic activity (regional range approximately 10-70 nT) during the observational period significantly (P < 0.05) increased the proportion of nightly seizures. The effect sizes (6-8%) for both magnetic sources were comparable and additive. Concerted efforts to experimentally simulate the temporal profiles of geomagnetic activity may help reveal the neuromechanisms by which biobehavioral changes during geomagnetic perturbations occur within susceptible populations.

Animals↗

PubMed1997

Geophysical variables and behavior: LXXXII. A strong association between sudden infant death syndrome and increments of global geomagnetic activity--possible support for the melatonin hypothesis.

A significant subpopulation of young infants who die suddenly (SIDS) often exhibit anomalies consistent with disruptions within the pineal-limbic system. We have hypothesized that sudden decreases in nocturnal melatonin by a specific range of geomagnetic activity would precipitate sudden infant death. A correlation of .90 was found between the numbers of cases of Sudden Infant Death Syndrome per month during the years 1960 and 1961 in Ontario and an increase (primarily) in numbers of days per month with average geomagnetic activity between 11 and 20 nT and 31 through 40 nT but a decrease in the numbers of days with values between 21 and 30 nT. This nonlinear sensitivity, presumably associated with specific ripple frequencies within the geomagnetic field, may explain the failure by other researchers to detect linear associations between the numbers of these types of deaths and gross, scalar indicators of geomagnetic activity.

Brain Chemistry↗

PubMed1997

Differential entrainment of electroencephalographic activity by weak complex electromagnetic fields.

The hypothesis was tested that compensatory susceptibility to electroencephalographic driving and entrainment by weak (1 microT) time-varying, externally applied complex magnetic fields would occur in normal subjects following successive stimulation by different patterns. 43% of the volunteers showed evidence of driving during the application of the complex magnetic fields and indications of resonance (entrainment) during the first 10 sec. following the cessation of the fields. The volunteers who exhibited driving and entrainment could be discriminated from those who did not by their more frequent reported experiences of fear and odd tastes during the stimulation. They were also more likely to have a preexposure history of a sense of presence and to experience intense meaningfulness when reading or writing prose or poetry.

Adult↗

PubMed1997

Depression following brain trauma is enhanced in patients with mild discrepancies between intelligence and impairment on neuropsychological scores.

Analysis of the MMPI (Minnesota Multiphasic Personality Inventory) scores from 135 (20 years to 60 years old) patients who had sustained closed head injuries supported the hypothesis of a nonlinear relationship between the severity of depression and the magnitude of the discrepancy between intelligence and neuropsychological proficiency. Although the MMPI Depression T scores for all groups of patients were elevated (M = 78, SD = 13), patients with the least and greatest discrepancies between intelligence and neuropsychological proficiency scored lower on Depression than patients with discrepancies within the z-score ranges -2.0 and -1.1. The results of symmetrical covariance for either depression or complex partial epileptic-like experiences before comparisons between groups suggested depression and the epileptic-like experiences share the same source of variance.

Adult↗

PubMed1997

"I would kill in God's name:" role of sex, weekly church attendance, report of a religious experience, and limbic lability.

Data collected during the last 15 years for the Personal Philosophy Inventory from 1.48 thousand university men (n = 629) and women (n = 853) were analyzed to discern the response characteristics of individuals who stated "yes" to Item 136 "If God told me to kill, I would do it in His name." The percentage (7%, range between 2% and 8% per year) of affirmative responses did not change significantly over time. The odds ratio for men: women for an affirmative response was 1.4:1. As predicted a four-way interaction for sex, weekly church attendance, history of a religious experience, and elevated complex partial epileptic-like signs was statistically significant. Of the men who reported a religious experience, attended church weekly, and displayed elevated complex partial epileptic like signs (5.7% of all males), 44% stated they would kill another person if God told them to do so.

Adult↗

PubMed1997

Metaphors for the effects of weak, sequentially complex magnetic fields.

Metaphors to explain the effects of weak, complex magnetic fields upon the neuromatrices of organisms are suggested. The ratio of the amplitude of the time-varying components to steady-state components for complex magnetic field for effective biological responses may display Weber values that are similar to those for the electrical activity of the brain, the detection of changes in sound pressure by the ear and for more classical sensory thresholds. The nonlinear, suprathreshold characteristic of weak magnetic field effects would be similar to the effective narrow windows of concentrations of ligands values for receptor subtypes with different affinities. Signals composed of trains of between 100 and 1000 successive, fast (1 to 3 msec.) transients, which would contain the most biological information, would require low amplitudes to which the substrates could respond and with which the neuromatrix could resonate.

Astronomical Phenomena↗

PubMed1997

Emergent properties following brain injury: the claustrum as a major component of a pathway that influences nociceptive thresholds to foot shock in rats.

Flinch (pain) thresholds for electric current delivered to the feet were correlated with the amount of necrosis within the diencephalon and telencephalon for rats in which seizures had been induced by lithium and pilocarpine about two months before the testing. The shared variance of the quantitative damage within the claustrum, the anterior part of the paraventricular nucleus of thalamus, (central) mediodorsal thalamus, and lateral amygdala (ventromedial part) explained 81% of the variance in the nociceptive (flinch) thresholds. A primary role of the claustrum within the neuropathways that mediate the response to the interoceptive and "painful" characteristics of stimuli is indicated. The concept of primary pathways versus "emergent" pathways subsequent to excitotoxic damage within the neuromatrix is discussed.

Animals↗

PubMed1997

Reported prevalence of unconsciousness from mechanical impact to the head in university populations during a fifteen-year period.

The prevalence of at least one episode of unconsciousness during childhood due to a mechanical impact to the skull was inferred by the response to one item embedded within a questionnaire of 140 items. 50% of the 633 university men and 33% of the 863 university women reported such unconsciousness; the prevalence did not change significantly between samples over a 15-yr. period. Multiple regression analysis indicated that the 10 items most strongly associated with the report of childhood unconsciousness did not explain more than about 10% of the variance. The majority of the items were those associated with complex partial epileptic-like signs and included (adult) episodes of memory blanks, mystical experiences, dissociation, and sudden meaningfulness.

Adolescent↗