John Gaito’s research while affiliated with University of Waterloo and other places

The use of 1- or 3-Hz brain stimulation has been effective in eliminating or preventing kindling behavior produced by 60-Hz stimulation. In this paper, statistical data are presented on the effects of duration of stimulation on suppressing this kindling behavior. For experimental rats, each daily experiment involved the sandwiching of the kindling-producing agent (60-Hz sine wave stimulation) between trials of the suppression-producing agent (1-Hz or 3-Hz sine waves) (i.e., a sequence of 1-60-1 or 3-60-3). The durations used were 0 (control), 5, 15, 30, 60, 120, 180, 300, and 600 sec. In general, the degree of suppression increased with increasing duration of stimulation. Recovery from suppression following 15 or 16 days of nonstimulation decreased with increasing durations. Complete, or near complete, recovery resulted with durations of 60 sec or less; however, there was some recovery in all groups.

A short discussion of multiple-comparison procedures is presented. The types of procedures used by experimental psychologists as reported in one general experimental psychology journal during a 2-year period (1978-1979) were determined. A variety of such procedures were employed. It is suggested that any set of multiple comparisons desired by a researcher can be obtained quickly and efficiently by multiple F tests within the ANOVA framework.

Animals subjected periodically to low-intensity electrical stimulation unilaterally to the amygdala or some other brain sites gradually develop automatic behaviors which culminate eventually in convulsions. Characteristic brain wave patterns accompany these behavioral changes. A 60-Hz sine wave with a 24-h interval provides the most optimum condition of stimulation. This kindling effect shows some characteristics similar to learning events, viz, relatively permanent changes, positive and negative transfer effects, involvement of limbic system. The results suggest that two factors are involved in the kindling process: a long-term effect of positive nature (probably due to modified neural circuitry) and a short-term “aftereffect” of negative nature.

There are three types of interference effects during kindling: that produced by alternate stimulation of homologous brain sites, by successive stimulation of one site, and by stimulation of one site by different frequencies. These three types of interference appear to be similar. Facilitation and interference effects during kindling seem to be generated by the operation of two factors: a “neurological trace” process, possibly involving synaptic changes, and an “aftereffect.” The latter process may be the main basis for these interference effects.

A DNA-RNA successive competition experiment in which DNA is hybridized first with brain RNA from rats subjected to forced motor activity and then with brain RNA from shock avoidance trained rats suggests that unique RNA species are synthesized during this latter task.

Previous experiments indicated that the development of clonic convulsions could be retarded by intraperitoneal injections of brain homogenate supernatant from male Wistar rats which had previously convulsed via amygdaloid electrical stimulation when naive recipients were used. Two further experiments were conducted with recipients which had reached the convulsion stage. In each of these experiments there was no indication of a retardation or suppressive effect.

These exploratory experiments investigated the effect of 3-Hz brain stimulation on behavior induced by 60-Hz brain stimulation when the former was presented simultaneously with, or following, the latter. In the simultaneous case, 3-Hz stimulation to one amygdala and 60 Hz to the other produced a slower kindling rate than did bilateral stimulation with 60 Hz. When 3-Hz stimulation followed six convulsion trials of 60-Hz stimulation, there was no effect on the convulsive tendency; however, with rats in which the convulsive pattern was relatively stable and 48 or more convulsive trials were followed by 24 trials of 3-Hz stimulation at double intensity or 36 trials at the same intensity as previous 60-Hz stimulation, a reversal effect was observed, that is, a return to nonconvulsive behavior.

Various solvents and chromatographic plates were used in thin layer chromatography in an attempt to determine unique patterns resulting during the kindling process. The patterns were the same for nonstimulated controls and for rats at various points of behavioral changes.

Previous research had indicated that an oscillation effect resulted during sequential alternation of unilateral amygdaloid stimulation with consistent low values for one side and consistent high values for the contralateral one. In the present study with two experiments, stimulation was of a single amygdaloid site over 10 phases of six clonic convulsions. The frequency of oscillation patterns was not greater than that expected by chance in the latency measure, which suggested that the oscillation effect results from the interaction between the homologous brain sites during the kindling process.

Kindling behavior culminating with clonic convulsions is produced by 60-Hz sine-wave stimulation of the amygdala. This behavior can be suppressed by stimulation of the same site with 1-Hz or 3-Hz sine waves. Such results have been obtained consistently over many experiments with the manipulation of a number of variables. Suppression appears to be a transient process in that rats will return approximately to their prestimulation thresholds following 2 weeks or more of rest. The severity of suppression is greatest with 120 s or more of sine-wave stimulation and when the intertrial interval is 1 or 3 hours. The effect decreases at 24 hours; at 72 hours, 5 days, and 14 days, it appears to be minimal or nonexistent. These results suggest that tissue damage is not the basis for suppression. Further evidence for this interpretation is provided by results indicating that suppression of kindled behavior is complete and permanent with a single trial of DC stimulation (which produces tissue damage), in contrast to 1-Hz stimulated rats, which show a slow, gradual increase in threshold values over many trials and a strong recovery from the suppression later on.