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A factor analysis of data from 10 phases of sequential alternation of amygdaloid stimulation within the kindling paradigm
Abstract
Data from a number of sequential alternation experiments were factor analyzed to determine the number of common factors present. Three dependent variables (latency of convulsion, number of trials to six convulsions, duration of convulsions) were evaluated by three procedures: principal components solution with 1s in main diagonals, principal axes solution with largest r in the diagonals, principal axes solution with R2 in the diagonals. The results were similar; the presence of two factors was suggested in the latency and criterion measures (primary site stimulation and secondary site stimulation) and one in the duration data. A principal components factor analysis over the three dependent variables showed the presence of three factors, those observed in each of the separate analyses.
... Nine of the 12 rats in Group 1 and all rats in Group 2 (or 20 of23 rats) had greater means in the test trials. These results are consistent with previous research in our laboratory (Gaito, Gaito, & Nobrega, 1977); latency to convulsion decreases and duration values increase over trials during the early convulsion trials. ...
... Furthermore, latency to convulsion decreases and the duration of convulsion increases as stimulation trials progress. Previously (Gaito et al., 1977), we found that the threshold for convulsion and latency and duration values become relatively stable after 24 or more CC trials. Thus, the threshold for convulsion with 60-Hz stimulation was determined for each rat used in Experiment 2, and 15 microA was added to this value (to handle possible daily fluctuations) as the effective threshold intensity (ETI). ...
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.
... The oscillation tendency in latency data has been remarkably resistant to a number of experimental manipulations. A summary of these results with integrating statistical analyses were reported by Gaito, Gaito, and Nobrega (1977). ...
... It is possible that one of the two brain sites stimulated naturally has a lower reactivity than does the contralateral one, thus resulting in consistently lower latency values. This possibility seems to be excluded by specific behaviors observed in previous research (Gaito, 1976b(Gaito, , 1976c(Gaito, , 1977a(Gaito, , 1977bGaito & Nobrega, 1977) which suggest the operation of an active inhibitory process. Although a rat may rear upon its hind paws immediately with stimulation of either side, the convulsion tends to occur quickly for one side but appears to be actively inhibited with stimulation of the other side. ...
Previous experiments using a sequence of alternating unilateral stimulations of the amygdalae indicated an “oscillation effect”, i.e., consistent low-latency values for convulsions elicited from one amygdala and consistent high-latency values for convulsions elicited by stimulation of the contralateral amygdala. The present study was concerned mainly with statistical evaluations of the reliability of oscillation events. Tests of the randomness of the observed primary and secondary oscillation patterns indicated that oscillation patterns were significant systematic ones in latency, criterion, and duration data, with the greatest frequency of oscillation occurring in the latency measure. Although there was no significant difference in the frequency of primary or secondary oscillation using chi-square methods, an analysis of variance trend analysis indicated that the primary oscillation pattern (low values on primary side) was the predominant one when considered over the total sample, 139 rats. Also, it was shown that the behavioral pattern (oscillation, nonoscillation) appears not to be related to the number of trials to reach the criterion of six convulsions. The exact basis for oscillatory behavior is unknown. However, for a number of reasons, it appears to be based probably on transfer and interference effects between the primary and secondary brain sites.
... In previous papers, we have described factor analyses concerned with determining the number of common factors underlying data involving phase means (Gaito, Gaito, & Nobrega, 1977)and also data involving each of the 60 convulsion trials (Gaito & Gaito , 1979). The results indicated two clearly separated factors in both cases with latency data (time between onset of stimulation and onset of convulsion): the primary site stimulation and the secondary site stimulation factor. ...
Data from a number of sequential alternation experiments for 125 subjects were factor analyzed to determine the number of common factors present. Three measures (mean latency of convulsion, mean number of trials to, six convulsions, mean duration of convulsions) were evaluated by principal components analyses. The presence of two factors was suggested in the latency, criterion, and duration measures (primary site stimulation, secondary site stimulation). The two factors were more clearly defined for the latency data than for the other measures. Further analyses with individual trials (rather than means) for the 125 subjects provided approximately the same results. Factor analyses of data from 35 rats stimulated only on one side showed the presence of one factor in all analyses. These results suggest a two-factor interpretation of kindling events, possibly the two effects of Goddard et al. and McIntyre and Goddard: a long-term neurological circuitry modification for each of the primary and secondary sites and a short-term aftereffect which accounts for the negative-transfer aspects from the primary to the secondary site.
... All product-moment correlation coefficients and the statistical manipulations were obtained within the Statistical Package for the Social Sciences, SPSS-I0, the University of Pittsburgh, on IBM 370 and DECsystem-l0 computers at York University. and the scree test (Gorsuch, 1974 (Gaito et al., 1977). For most of these analyses the two of these were below .300. ...
Data from a number of kindling experiments involving 60 convulsion trials were evaluated by a truncated principal components factor analysis to determine the number of common factors present. These data were obtained on 123 rats in which periodic low-intensity unilateral stimulation was alternated from one amygdala to the other after six convulsions on each side. Two dependent variables (latency of convulsion, duration of convulsion) were analyzed over Trials 1–60, 1–24, 25–60, 1–12, 13–24, 25–36, 37–48, and 49–60 for each dependent variable. Two factors appeared for all latency analyses: primary site stimulation (first side stimulated), secondary site stimulation (second side stimulated). The factor resolution was not clear for the duration measure; two to four factors were suggested in the various analyses.
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.
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.
Previous research indicated that an oscillation effect resulted during sequential alternation of unilateral electrical stimulation of the amygdala over 10 phases of six clonic convulsions per phase, with consistent low latency values for one side and consistent high values for the contralateral one (i.e., a fluctuation of low and high values on consecutive phases). In the present experiment 10 rats were stimulated for up to 50 phases. Four of the 10 showed remarkable patterns of oscillation in latency data: One oscillated on every one of 50 phases, two showed oscillation patterns on 48 of 50 phases, and the fourth oscillated on every one of 32 phases.
Previous research indicated that an oscillation effect resulted during sequential alternation of unilateral amygdaloid stimulation with consistently low latency values for one side and consistently high values for the contralateral one when 30 sec was the duration of stimulation. In the present experiment, stimulation was for 5 sec. The oscillation tendency was the same with 5 sec duration as it had been with 30 sec.
Previous research indicated that an oscillation effect resulted during sequential alternation of unilateral amygdaloid stimulation with consistent low-latency values for one side and consistent high values for the contralateral one. In this study only one trial of stimulation was applied before alternating to the opposite side. The oscillation tendency resulted under this condition in a similar fashion as in previous studies in which stimulation was continued with one side until six convulsions occurred.
Previous research indicated that an oscillation effect resulted during sequential alternation of unilateral amygdaloid stimulation with consistent low-latency values for one side and consistent high values for the contralateral one. One possible basis for this effect is that one of the two sides naturally has a greater reactivity to the stimulating current. This hypothesis was evaluated in this study. One group of rats had the usual alternation of stimulation from one side to the other over 10 phases of six convulsions each. A second group received five consecutive phases of stimulation of the primary site and then five consecutive phases for the secondary side. If the hypothesis were true, the latency values for one side would be consistently lower (or higher) than those for the phases on the other side; this result did not occur, although significant oscillation patterns were prominent with the alternation group. These results tend to suggest that differential natural reactivity of the two sides is not the basis for the oscillation effect.
Three groups of rats were subjected to a sequence of stimulations alternating from one amygdala to the contralateral one. Each phase of stimulation was for six convulsions prior to stimulation of the opposite side. Rats in Group 1 were stimulated six times per day; Group 2 rats had three trials each day; and one stimulation each day was provided for Group 3 rats. The oscillation tendency (high values for one side, low values for other side) was prominent with all groups but seemed most prevalent with Group 3 rats.
In two experiments, rats were subjected to a sequence of stimulations alternating from one amygdala to the contralateral one. Each phase of stimulation was for six convulsions prior to alternation to the other side. Rats In Experiment 1 had a series of six or seven phases of alternation, followed by five phases of bilateral stimulation, and concluded with seven phases of unilateral stimulation. In Experiment 2, rats had five phases of bilateral stimulation prior to seven phases of unilateral stimulation. The bilateral phases produced a modest disruption of the oscillation tendency when it was interspersed between two series of unilateral stimulation phases, more so in the criterion measure than in latency data. The effect was less on the oscillation tendency when bilateral stimulation preceded unilateral stimulation phases.
Three groups of rats were subjected to a sequence of electrical stimulations alternating from one amygdala to the contralateral one. In Group 1 each stimulation was for one convulsion prior to stimulation of the opposite side. Rats in Group 2 had six convulsions per phase. Twelve convulsions per phase were provided for Group 3 rats. The oscillation tendency (high values for one side, low values for the other side) was prominent with all groups, but seemed less prevalent for the rats in the one convulsion per phase group.
In two experiments, rats were subjected to a sequence of electrical stimulations alternating from one amygdala to the contralateral one. Each phase of stimulation was for six convulsions prior to alternation to the other side. An oscillation effect resulted, involving low trials to six clonic convulsions and low latency to convulse for stimulation of one side, but high values of these measures for the contralateral site. The oscillation persisted, especially for the latency measure, even when one phase of bilateral stimulation preceded unilateral stimulation, when a 17- to 23-day rest period was inserted following a sequence of alternations and when two phases of bilateral stimulation occurred following postrest unilateral stimulations. The oscillation effect was less prominent in the number of trials to six convulsions data and almost nonexistent in duration of convulsion. Of 16 rats used in 15 to 19 alternating phases, 7 oscillated throughout all of these phases in latency data, but none showed oscillation over all phases in the other dependent variables.
Fifteen rats showing prominent oscillation patterns in latency during sequential alternation of unilateral amygdaloid stimulation were separated into three groups of five rats each. Group 1 rats were rested for 1 month prior to continuing sequential alternations. Groups 2 and 3 rats were rested for 3 months and 6 months, respectively. In spite of these rest intervals, most rats continued to show the same oscillation pattern as that before the rest period.
Five experiments were conducted in which donor rats were kindled to the clonic-convulsion stage, sacrificed, and their brains removed. The brain was homogenized, and the supernatant fraction was injected intraperitoneally into recipient experimental rats, who then were subjected to the kindling procedure. Control donors which received no stimulation were included. When the injection involved two or more brain amounts, a retarding effect tended to occur with the experimentals. If only one brain amount was used for the injection, no change resulted in the kindling rate of these recipients. This interanimal negative-transfer effect appears to be similar to the intraanimal negative-transfer effect reported by Mclntyre and Goddard.
In 2 experiments, a total of 25 aged Wistar male rats (approximately 420-475 days old) were subjected to stimulation of each amygdala in an alternating sequence. Their behavioral response to this stimulation was similar to that found previously with younger rats, systematically going from normal exploration, to automatic behavior, to clonic convulsions. Results also show the "oscillation effect," i.e., low values in latency when stimulated on one side and high values when stimulated on the opposite side. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
The kindling effect is described as involving a gradual change in behavior in response to periodic invariant electrical stimulation of specific brain sites, culminating in convulsions. Two premises are evaluated relative to kindling: (a) The kindling effect provides an excellent model of human epileptic conditions. (b) The amino acid taurine will act to suppress convulsions developed during kindling. Consideration of behavioral, electrophysiological, neurological, and chemical aspects of kindling suggest that behavioral aspects may model those of epilepsy, but it is probable that neurological mechanisms in some types of epilepsy are different from those underlying the kindling event. Although taurine appears to have an important role (e.g., as an inhibitory neurotransmitter) and has been successful in suppressing convulsions in humans and in some experimentally induced seizures, it has been found to have no effect on convulsions developed via kindling. (65 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
An investigation was made of both primary and "transfer" kindling as they occur in ipsilateral limbic sites. Primary kindling was found to involve progressive growth of afterdischarge (AD), propagation and convulsive behavior. It was noted that AD growth did not take place gradually but occurred in sudden, large increments. "Transfer" (a significant acceleration of secondary kindling) was found at every secondary limbic site. It was associated with the early appearance of full-blown AD's, super-normal propagation, and well-developed seizures. The post-transfer interference of primary site function previously reported by Goddard et al was also found, but it occurred in significant amounts only after transfer kindling of the amygdala. It is believed that the data offer some support for both of the hypothetical mechanisms of transfer which have been proposed.
Bipolar electrodes were implanted into the amygdala of each hemisphere of adult male rats. A short burst of low-intensity stimulation was applied to one of these electrodes once each day. Initially there was little response. With repetition, epileptiform responses progressively developed until each daily stimulus triggered a behavioral convulsion (kindling effect). Following six convulsions, the procedure was applied to the contralateral hemisphere. Convulsions were observed to kindle more rapidly, especially if a rest interval of 2 weeks followed the last primary site convulsion. When stimulation was reapplied to the primary site, convulsions were not triggered. This was associated with failure to evoke local after-discharge and/or failure of the after-discharge to propagate. Several trials were necessary to re-establish convulsion, unless a 2 week rest preceded testing, in which case convulsions were triggered on the first trial. Following a series of convulsions triggered from either hemisphere, the contralaterally triggered convulsions, when they appeared, showed consistently longer onset lattencies. These latency shifts were attentuated when rest intervals preceded the testing. Latency shifts and seizures failures were not observed if the preceeding series of convulsions was reduced from six to one. Lesions at the tip of either electrode had little effect on the results obtained in the contralateral hemisphere. Together, the results imply that: kindling establishes a lasting trace which is both transynaptic and widespread, kindling from a second location establishes a second trace utilizing parts of the existing trace, a series of convulsions leaves a less durable after-effect with a decay time of about 2 weeks and which interferes with various aspects of seizure activity, and the trace which activates the convulsions is less susceptible to interference from the after-effect.
Brief bursts of nonpolarizing electrical brain stimulation were presented once each day at constant intensity. At first the stimulation had little effect on behavior and did not cause electrographic afterdischarge. With repetition the response to stimulation progressively changed to include localized seizure discharge, behavioral automatisms and, eventually, bilateral clonic convulsions. Thereafter, the animal responded to each daily burst of stimulation with a complete convulsion. The effect was obtained from bipolar stimulation of loci associated with the limbic system, but not from stimulation of many other regions of the brain. Parametric studies and control observations revealed that the effect was due to electrical activation and not to tissue damage, poison, edema, or gliosis. The changes in brain function were shown to be both permanent and trans-synaptic in nature. Massed-trial stimulation, with short inter-burst intervals, rarely led to convulsions. The number of stimulation trials necessary to elicit the first convulsion decreased as the interval between trials approached 24 hours. Further increase in the inter-trial interval had little effect on the number of trials to first convulsion. High-intensity stimulation studies revealed that the development of convulsions was not based simply on threshold reduction, but involved complex reorganization of function. Experiments with two electrodes in separate parts of the limbic system revealed that previously established convulsions could facilitate the establishment of a second convulsive focus, but that the establishment of this second convulsive focus partially suppressed the otherwise permanent convulsive properties of the original focus.
Interanimal negative transfer of the kindling effect. Physiological Psychology The oscillation effect during sequential alternation of amygdaloid stimulation with aged rats
- I Gaito
- S T Galto
- ·382 Gaito
- I Nobrega
GAITO, I., & GAlTO, S. T. Interanimal negative transfer of the kindling effect. Physiological Psychology, 1974, 2, 379·382. GAITO, I., & NOBREGA, I. The oscillation effect during sequential alternation of amygdaloid stimulation with aged rats. Bulletin of the Psychonomic Society, 1977, 9, 151-154.
Interanimal negative transfer of the kindling effect
- I Galto
GAITO, I., & GAlTO, S. T. Interanimal negative transfer of the
kindling effect. Physiological Psychology, 1974, 2, 379·382.
No te -CP =cumulative proportion of variance ex tracted. REFERENCES BURNHAM, W. M. Primary and "transfer" seizure development in the kindled rat
No te -CP =cumulative proportion of variance ex tracted.
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