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Biomedical subjects

J Caston

Publications and source records attributed to J Caston.

At least 37 records · Page 2Linked to original sources
PubMed1995

Effects of lesion of the inferior olivary complex in learning of the equilibrium behavior in the young rat during ontogenesis. I. Total lesion of the inferior olive by 3-acetylpyridine.

Young DA/HAN strain rats were submitted to an equilibrium test consisting in maintaining equilibrium upon a rotorod rotating at 10 or 20 rpm. They were either intact or lesioned, the lesion consisting in destruction of the inferior olivary complex (IOC) by 50-95 mg/kg i.p. administration of 3-acetylpyridine (3-AP) at day 15, followed, 2 to 4 h later, by i.p. injection of niacinamide (300 mg/kg). All the 3-AP-treated animals included in this study were completely lesioned, the extent of the lesion being estimated by both the response of the rats to harmaline and histological controls at the end of the experiments. The IOC lesioned rats were either naive (tested at one given day) or trained every day (10 trials per day); among the latters, some were trained before and after the lesion, the others being trained either before or only after. Control rats were submitted to the same training schedule. Both quantitative (time during which the animals maintained the equilibrium upon the rotating rod) and behavioral data (strategy used by the animals to maintain equilibrium) were obtained. The results demonstrate that, compared to those of controls rats, the quantitative and behavioral scores of the IOC lesioned animals were altered. Comparison of naive and trained animals shows that the impairment of the equilibrium behavior is not only due to the ataxia provoked by the IOC lesion but is also due to cognitive deficits. However, prelesion training facilitates the acquisition of a more efficient postlesion equilibrium behavior. From these results, it can be concluded that the olivo-cerebellar pathway is involved in the adaptation of motor behavior to the environmental conditions.

Aging↗
PubMed1995

Differential roles of cerebellar cortex and deep cerebellar nuclei in the learning of the equilibrium behavior: studies in intact and cerebellectomized lurcher mutant mice.

Three- to 6-month-old lurcher mutant mice (+/lc), which exhibit a massive loss of neurons in the cerebellar cortex and in the inferior olivary nucleus but whose deep cerebellar nuclei are essentially intact, were trained daily, for 9 days, to maintain their equilibrium upon a rota rod rotating at 20 or 30 revolutions per minute (rpm). Their scores were measured and their behavior upon the rotating rod quantified in comparison to those of matched control (+/+) mice. Lurcher mice were able to learn to maintain their equilibrium efficiently when rotated at 20 rpm but were not when rotated at 30 rpm. After cerebellectomy, the equilibrium capabilities of the animals were much altered, especially in +/lc. These results show that the deep cerebellar nuclei are sufficient for motor learning, provided the task is not too difficult (20 rpm), but that the cerebellar cortex is required when the task is more difficult (30 rpm). Therefore, it can be concluded that the adaptive motor capabilities of lurcher mice are less developed than those of control animals.

Animals↗
PubMed1995

Role of preoperative and postoperative sensorimotor training on restoration of the equilibrium behavior in adult mice following cerebellectomy.

The equilibrium behavior of cerebellectomized C57/BL6 adult mice was studied on a rota rod rotating at 20 revolutions per minute and the influence of preoperative or/and postoperative training on restoration of equilibrium capabilities investigated. The duration of the preoperative training was either short (1 day) or long (7 days). The postoperative training began either the day after cerebellectomy or was delayed by 7 days. The results demonstrate that postoperative training was efficient in restoring the equilibrium behavior in all cases, except for the animals which were trained for a long period (7 days) before the lesion. Preoperative training was also efficient providing it was long enough (7 days), except for the animals which postoperative training began the day after cerebellectomy. It can be stated that both preoperative and postoperative trainings influence the restoration of the equilibrium following a cerebellectomy and that, in some instances, preoperative training can be as efficient as postoperative.

Animals↗
PubMed1995

Vestibular compensation in the European green frog (Rana esculenta L.) and effect of training on compensation.

Compensation of the vestibular deficits following section of the ampullary nerve of a horizontal semicircular canal was studied from a behavioral point of view in the European green frog. Post-rotation reactions, which are highly asymmetrical the day after the lesion, become symmetrical, as they are in intact animals, 45-60 days later. It was shown that vestibular and motor training given postoperatively did not enhance the rate at which compensation was achieved.

Afferent Pathways↗
PubMed1994

Effect of administration of 3-acetylpyridine followed by niacinamide injection on survival, extent of the inferior olivary complex lesion, and response to harmaline in the young rat.

In the 15 day-old DA/HAN strained rat, i.p. injection of 3-acetylpyridine (3-AP) 50, 65 or 95 mg.kg-1 was followed 2 to 4 hours later by administration of niacinamide (300 mg.kg-1). The percentage of survival and the extent of the inferior olivary complex (IOC) lesion, determined histologically, were correlated with both the dose of 3-AP administered and the time delay between 3-AP and niacinamide injections. Moreover, the tremor elicited by harmaline was also correlated with the extent of the IOC lesion. The results show that it is more advantageous to administer 95 mg.kg-1 3-AP and to delay niacinamide injection by 2h30 or less to get the higher percentage of survival (about 90%) and a reasonably high percentage of totally IOC lesioned rats (more than 30%). They also demonstrate that the harmaline test is not sufficient to acutely judge of the extent of the IOC lesion and that, in all cases, histological controls have to be done. The results are discussed in terms of interrelationships of the variable studied.

Animals↗
PubMed1994

Effects of inhibition of the GABAergic systems by picrotoxin on retention of a nociceptive experience in the rat, with special reference to the influence of cerebellar cortex output.

Adult cerebellectomized and noncerebellectomized DA/HAN strain (pigmented) female rats were submitted to a one-trial passive avoidance conditioning procedure consisting in associating darkness with a nociceptive stimulus. Seven days later, they were tested again to assess the retention stage. The results demonstrate that in noncerebellectomized rats, picrotoxin, whatever the dose, administered prior to the retention test, does not significantly impair retrieval. On the contrary, when administered just prior to the initial conditioning, impairments of the initial single nociceptive experience were evident (the greater the picrotoxin dose, the greater the impairments). In animals that were cerebellectomized 1 week before the experiment, picrotoxin administered at a low dose before the initial experience elicited memory impairments that were similar to those induced in noncerebellectomized rats but that were greater than those elicited in cerebellectomized, nontreated animals. However, in cerebellectomized rats, picrotoxin administered at a low dose elicited memory impairments that were weaker than in noncerebellectomized animals injected with a high dose of the drug. Considering that a low dose of picrotoxin administered to cerebellectomized animals had effects that were similar to those of a high dose injected to noncerebellectomized rats, and given that it has previously been demonstrated that a cerebellectomy performed after a single nociceptive experience impairs its memory, it is tempting to suggest that the two different doses of the drug administered to cerebellectomized and noncerebellectomized rats have similar effects on memory. If such an interpretation is valid, the information would have to leave the cerebellar cortex to be stored for long.

Animals↗
PubMed1993

Can analysts agree? The problems of consensus and the psychoanalytic mannequin: I. A proposed solution.

Psychoanalysis, plagued by lack of demonstrable consensus on clinical formulations, is as much endangered by overinflated agreement from stereotypical dynamic formulas: tests of psychoanalytic hypotheses derived from any such formulations may therefore rest on questionable foundations. The problems that give rise to artifactual overagreement or failure to reach agreement are here traced in earlier empirical psychoanalytic research. Review reveals that although new and inventive empirical strategies (applied in the last two decades) achieve adequate success in the area of agreement, they demonstrate little headway in ruling out that stereotypy may underlie such consensus. The present investigation offers a solution for testing agreement in complex clinical psychoanalytic propositions, in a way that sets up a "test of the mannequin": that is, whether stereotypical assumptions about the patient's dynamics are overridden (revised) by the specific character of a given patient's narrative. The mannequin concept introduces a new and epistemically crucial consideration in the making of psychodynamic formulations and is relevant to both empirically controlled and clinical contexts of observation and formulation. No psychoanalytic paradigm, whether classically ego-psychological, self-psychological, control-mastery, or object-relational, escapes this problem.

Humans↗
PubMed1993

Can analysts agree? The problems of consensus and the psychoanalytic mannequin: II. Empirical tests.

The present investigation reports on the execution of an empirical strategy for testing agreement in complex clinical psychoanalytic propositions, and for testing whether stereotypical assumptions are overridden (revised) by the specific character of the patient's narrative. The findings reveal that, in general, for the several domains of psychoanalytic formulation, psychoanalyst judges reach superior levels of ordinal agreement, and modest to good levels for agreement on magnitude. Moreover, formulations based on verbatim psychoanalytic sessions pass the "test of the mannequin" in most domains, i.e., surpass stereotypical psychoanalytic assumptions about the patient's dynamics. The mannequin concept, here operationalized, introduces a new and epistemically crucial consideration for the making of psychodynamic formulations. Other novel contributions of these studies include the development of operationalized measures of (reconstructive) historical linkage, and the introduction of magnitudinal agreement in this empirical area.

Adult↗
PubMed1992

Effects of lesion of the inferior olivary complex by 3-acetylpyridine on learning and memory in the rat.

DA/HAN-strained male rats (pigmented rats) were submitted to two experimental tasks consisting of spatial learning (water-escape) and a passive avoidance conditioning. Both these tasks were performed by different animals. In order to destroy the inferior olivary complex, the animals were injected with 3-acetylpyridine either 9 days prior to the initial learning session or 24 h after completion of the learning task. They were retested (retrieval test) 10 days after the initial learning was achieved. Learning and retention were compared to those noted in control rats. Administration of 3-acetylpyridine before the initial learning did not prevent the spatial learning but the scores were greatly altered and the number of trials needed to reach the fixed learning criterion was much greater than in controls. However, 10 days later the animals had memorized their initial experience. Injection of 3-acetylpyridine after the initial learning session impaired memory: the animals had completely forgotten their initial learning. It can therefore be concluded that lesion of the afferent climbing fibres to the cerebellar cortex alters learning and retention of a spatial task. Such a lesion does not interfere with learning and retention of a passive avoidance conditioning, since in this condition the experimental animals injected with 3-acetylpyridine either before or after the initial learning behave similarly to controls. The effects of the inferior olivary complex lesion are obviously different according to the task to be learnt, suggesting that these two tasks do not require the integrity of the same nervous structures.

Animals↗
PubMed1992

Role of the cerebellum in habituation exploration behavior in the rat.

Adult control and cerebellectomized DA/HAN-strained male rats were submitted to habituation of exploration behavior in a test environment consisting of a novel cage in which four objects were displayed. Seven days after the initial session of habituation, retention of the habituation was tested. Within-session habituation was observed in cerebellectomized and control rats. However, retention of habituation was impaired in rats that were cerebellectomized after the initial session but not in those cerebellectomized before the session. These results are consistent with the hypothesis that the cerebellum has a role in memory of habituation to environmental stimuli.

Animals↗
PubMed1992

Role of the cerebellum in spatial orientation in the rat.

Adult DA/HAN strain rats were submitted to a spatial orientation task consisting of finding a reward in an open field. They were first submitted to an initial learning session and 10 days later to a retrieval test. The animals were divided into four groups of five rats each: animals that were cerebellectomized before the initial learning session or after the initial learning session, sham-operated rats, and control (intact) animals. Different parameters that characterize the spatiotemporal organization of the rat's exploratory behavior were quantified. From the results, it can be concluded that the cerebellum is not absolutely necessary in the processes that sustain spatial learning but that it is involved in the mechanisms sustaining focused spatial memory and in the cognitive processes of the motor program elaboration and not only in the regulation of the movement being done.

Animals↗
PubMed1991

Cerebellum and memory: an experimental study in the rat using a passive avoidance conditioning test.

Adult DA/HAN strain rats were submitted to a one-trial passive avoidance conditioning procedure consisting in associating darkness with a nociceptive stimulus. Seven or fourteen days after the one-trial initial experience, they were tested again in order to know whether they had forgotten it or not. The animals were divided into two experimental groups, the rats being either conditioned (COC group) or not (NOC group) before cerebellectomy, and two control groups, the animals being either intact (C group) or sham-operated (SO group). Each group was divided into two subgroups, one being given the retrieval test 7 days and the other 14 days after the initial conditioning. The results show that retention in C, SO and NOC rats was similar whether the animals were tested 7 days or 14 days after the initial one-trial conditioning. Seven days after their initial experience and the cerebellectomy, the retention in COC rats was null while when they were tested 14 days after cerebellar removal these animals had much better scores, significantly higher than 7 days after the lesion. It is concluded that the cerebellum is involved in the consolidation processes of the memory trace but is not the site of memory storage.

Animals↗
PubMed1990

Effects of cerebellectomy at day 15 on the ontogenesis of the equilibrium behavior in the rat.

Young cerebellectomized and control (sham-operated) DA/HAN strained rats, 1 day to 1 month old, were submitted to an equilibrium test consisting for the animals in maintaining their equilibrium when placed on a horizontal mast rotating around its longitudinal axis at 10 or 20 rpm (slow and fast rotation rates, respectively). Cerebellectomized animals, operated when 15 days old, were either naive (tested at one given day) or trained; these last ones were trained before and after the operation, or only before, or only after, according to a slow or a fast rotation rate. Control rats were also either naive or trained in conditions similar to those given to operated animals. Relevant comparisons show that: (1) rats cerebellectomized at day 15 which have not been trained before the operation are unable to learn a given motor pattern. (2) When trained before the operation, the animals learn the motor patterns that they use to maintain their equilibrium upon the rotating mast as well as controls. (3) Postoperative training is inefficient in the acquisition of the equilibrium behavior whether the animals were trained preoperatively or not. (4) Compared to the slow rotation rate (10 rpm), the evolution of the equilibrium behavior in cerebellectomized rats is not altered when the rotation rate is increased to 20 rpm, that is when the task is more difficult.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1990

Role of the cerebellum in an avoidance conditioning task in the rat.

Adult DA/HAN strain male rats were submitted to an avoidance conditioning procedure. They were divided into two experimental groups, the animals being either conditioned (COC group) or not (NOC group) before cerebellectomy, and two control groups, the animals being either intact (C group) or sham-operated (SO group). Although the NOC rats could be conditioned successfully and the cerebellum is not absolutely necessary for the avoidance conditioning achievement, their scores were significantly lower than the preoperative scores of COC rats. Moreover, the scores of NOC rats (postoperative scores) were significantly lower than the postoperative scores of COC animals, suggesting that the preoperative conditioning makes the postoperative conditioning easier. At last, comparing postoperative scores of COC rats with those obtained by C and SO rats when given the retrieval test and comparing preoperative and postoperative scores in COC animals show that retention of the initial (preoperative) conditioning is partly abolished by the cerebellectomy. Histological controls demonstrated that the entire cerebellum except for the flocculus and the nodulus was removed. These results strongly suggest that the cerebellum is involved in the memory processes that sustain the avoidance conditioning.

Animals↗
PubMed1989

Role of the cerebellum in the ontogenesis of the equilibrium behavior in the young rat: a behavioral study.

Young cerebellectomized and control DA/HAN strained rats, one day to 1 month old, were submitted to an equilibrium test. Cerebellectomized animals, operated when 10-, 20- or 24-day-old, were either trained-operated-trained (trained every day before and after cerebellectomy), naïve-operated-trained (cerebellectomized while naïve and trained every day after the operation), or naïve-operated-naïve (tested at one given day after the operation). Control rats were either trained-controls (trained every day) or naïve-controls (tested at a given day). Relevant comparisons show that (1) in control rats, the maturation of the equilibrium behavior does not depend on a specific training, at least to a great extent; however, training increases the rate of acquisition of the maximal score. (2) Rats cerebellectomized at day 10 and trained after cerebellectomy only are not able to learn a given motor pattern, while rats cerebellectomized by the 20th or 24th day are; however, their scores are always lower than those of control animals trained from the same age. Cerebellectomy alters the ontogenesis of the equilibrium behavior more especially as the operation is early. (3) Impairments of the equilibrium behavior after cerebellectomy can be explained by both motor disorders and learning processes deficiency. (4) Preoperative training counterbalances the effects of cerebellectomy in improving postoperative scores only when the cerebellum is removed at day 24. From these results it can be concluded that, in the rat, the cerebellum is involved in the learning processes that sustain the ontogenesis of the equilibrium behavior as it is in other motor learning mechanisms.

Animals↗
PubMed1985

Influence of stimulation of the visual system on the activity of vestibular nuclear neurons in the frog.

In the frog (Rana esculenta L.) we have tested the possible existence of visual inputs in the vestibular nuclei by recording the activity of second-order vestibular neurons receiving primarily horizontal canal inputs, while the visual system was stimulated by either light pulses or optokinetic stimulation; moreover, combined visuovestibular stimulation (horizontal rotatory stimulation in light) was performed and the response compared to the one obtained during vestibular stimulation alone (horizontal rotatory stimulation in dark). 42.2% of the neurons tested (38/90) responded to light pulse stimulation of the retinae by an increase of their discharge frequency of about 150%, while the other neurons (57.8%) did not. Optokinetic stimulation was completely ineffective in modulating the discharge frequency of all the neurons (98) recorded. Among 30 neurons tested during constant-velocity horizontal rotation of the turntable (2.5-10%s) in the excitatory direction, 13 units (43.3%) had a discharge rate significantly greater than the spontaneous frequency during the constant-velocity phase when the rotation was performed in light, while a few seconds after beginning of the constant-velocity phase the discharge frequency returned to its resting value when the rotation was performed in dark. Moreover, the difference between the maximum discharge frequency and the resting discharge frequency (delta F) was significantly higher in light than in dark. The behavior of the 17 other neurons (56.7%) was similar whether the rotation was performed in light or in dark. When tested to sinusoidal rotation (0.05 Hz +/- 40 degrees or 0.1 Hz +/- 30 degrees), the characteristics of the responses were different in light and in dark.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Influence of stimulation of auditory and somatosensory systems on the activity of vestibular nuclear neurons in the frog.

In the frog, we have recorded extracellularly the activity of vestibular nuclear neurons driven by the horizontal semicircular canals. About 28% of the neurons recorded (n = 300) responded to auditory stimulation (clicks 150/s and pure tones 300-2,000 Hz, about 80 dB above threshold) or to somatosensory stimulation (electrical stimulation of the ipsilateral or contralateral sciatic nerve and vibratory stimulation of the ipsilateral gastrocnemius). Whatever the stimulus, the response was always an increase of the discharge frequency. Such a frequency increase was much more important for somatosensory stimulation (62-145%) than for auditory (20%) and sciatic nerve input was about twice as efficient as gastrocnemius input. Except for type IV units which were only exceptionally recorded, all the other neuronal types (according to Duensing and Schaefer 's classification, 1959) responded to auditory or somatosensory volleys. In particular, activation of type III units, which are partly efferent vestibular neurons ending at the base of the sensory hair cells, may result in a modulation of the peripheral vestibular discharges. The latencies of the responses varied over a wide range (5-40 ms); long latency responses are probably mediated by polysynaptic pathways including the reticular formation and/or the cerebellum, and short latency ones by oligosynaptic pathways. These pathways and the functional meaning of convergence of auditory and somatosensory input onto vestibular nuclei are discussed.

Afferent Pathways↗