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J A Wada

Publications and source records attributed to J A Wada.

At least 19 recordsLinked to original sources
PubMed1999

Role of the midline brainstem in feline amygdaloid kindling.

PURPOSE: To study the role played by the midline brainstem in feline amygdaloid kindling in general and the formation of transhemispheric positive transfer effect (PTE) in particular. METHODS: Eight adult male cats with either anterior or posterior midline brainstem bisection underwent primary and secondary site kindling and primary site retest. RESULTS: Stage 4 seizure pattern was altered with either absence of contralateral circling in the anterior group or emergence of ipsilateral circling in the posterior group. Electroclinical manifestation of the tonic phase was absent in the posterior but not the anterior group. Kindled convulsive pattern remained asymmetrical with contralateral dominance in the anterior but not the posterior group. Intermittent truncation of the secondary clonic phase of the kindled seizure occurred in both groups. PTE was reduced whereas the negative transfer effect was preserved in both groups. CONCLUSIONS: The anterior half of the midline brainstem participates in stage 4 contralateral circling. Both the anterior and posterior halves of the midline brainstem participate in the mechanisms of repetitive circling during stage 4 and the stable maintenance of the kindled stage 6 seizure. The anterior and posterior halves of the midline brainstem participate in symmetrical patterning and electroclinical tonic expression of the kindled seizure, respectively. The midline brainstem, extending from the midbrain to the pons with some posterior emphasis, participates in the mechanisms of PTE formation. The findings indicate the importance of the brainstem for electroclinical ictal processes and a transhemispheric positive transfer effect associated with temporal limbic epileptogenesis.

Amygdala↗
PubMed1998

Amygdaloid kindling in brainstem bisected cats.

Results of previous studies suggested that the brainstem participates in amygdaloid (AM) kindled seizure generalization and the positive transfer effect at the secondary site AM. This study was undertaken to define the role of the brainstem in the patterning of AM kindling, the maintenance of AM kindled seizure and the formation of the positive transfer effect (PTE) at the secondary site AM in cats. Seven animals with midsagittal bisection of the brainstem were subjected to primary site and secondary site AM kindling and primary site retest. All the animals were kindled at the primary site. However, the following significant differences from the pattern seen in intact animals were observed: (1) reversed direction of stage 4 seizure, with circling from the contralateral to the ipsilateral, (2) a marked kindled seizure stage instability, and (3) frequent abortive termination of the kindled seizure. At the secondary site AM, all the animals showed a complete absence of the positive transfer effect, with two out of seven animals failing to progress beyond stage 2. A negative transfer or an interference after-effect remained preserved at the secondary site kindling and primary site retest. The findings indicate that the bisected midsagittal area in the brainstem plays an important role not only in the patterning and maintenance of the kindled seizure but also in the formation of the transhemispheric positive transfer effect in feline AM kindling.

Amygdala↗
PubMed1997

The effect of electrolytic lesioning of the midbrain prior to amygdala kindling in rats.

Effect of midline electrolytic lesioning in the midbrain was examined in rodent amygdala (AM) kindling. During the primary site AM kindling, the lesioned rats (n = 5) needed a significantly larger number of stimulations to reach a final stage of kindled seizures (stage 5) than the sham operated ones (n = 5). During the contralateral secondary site AM kindling, none of the former animals showed a positive transfer effect (a reduction in the number of stimulations to reach stage 5), whereas all of the latter ones did. The findings indicate that in rats the lesioned area of the brainstem participates not only in the development of primary site AM kindling but also in the mechanism of transhemispheric positive transfer effect.

Amygdala↗
PubMed1997

Involvement of the claustrum in the convulsive evolution of temporal limbic seizure in feline amygdaloid kindling.

The effects of unilateral lesioning of the claustrum (CL) either prior to or following completion of amygdaloid (AM) kindling was examined in cats. CL lesioning ipsilateral to the kindling or the kindled AM caused the emergence of a mirror image pattern of expected or established AM onset convulsive seizure originating in the contralateral hemisphere. This finding suggests that: (1) the CL is involved in the convulsive evolution of AM onset non-convulsive limbic seizure; (2) an alternative transhemispheric route is available for the convulsive evolution of AM onset limbic seizure when the ipsilateral CL is disrupted; and (3) the CL is not critical for secondary convulsive generalization.

Amygdala↗
PubMed1997

Role of the claustrum in convulsive evolution of visual afferent and partial nonconvulsive seizure in primates.

PURPOSE: We tested cross-species validity of the role of the claustrum in the convulsive evolution of the visual afferent and amygdaloid seizure and the specificity of the claustral lesioning effect. METHODS: In 7 Senegalese baboons, we examined the effect of unilateral claustral lesioning on generalized convulsive seizures either kindled from the amygdaloid nucleus (AM) and cingulate cortex (CG) or induced by intermittent photic stimulation (IPS) after systemic administration of D,L-allylglycine (AG). RESULTS: A lesioned area common to all animals was the anterior half of the left claustrum. Postoperative restimulation of the kindled left AM or CG evoked only nonconvulsive seizures. When few convulsive seizures emerged in 1 CG-kindled animal, they were mirror image of the kindled seizure and arose from the nonlesioned right hemisphere. Restimulation of the kindled right AM or CG reactivated kindled seizures. An IPS-induced generalized convulsive seizure was transformed into a secondarily generalized seizure arising from the nonlesioned right hemisphere. CONCLUSIONS: The primate claustrum regulates the convulsive evolution of partial seizures originating from nonmotor structures such as the AM and CG and also regulates the convulsive development that follows IPS. Our findings suggest that predisposed susceptibility expressed at the claustrum may be involved in the clinical variation with respect to convulsive evolution of nonmotor partial seizures and convulsive susceptibility to IPS in human primates.

Allylglycine↗
PubMed1995

Amygdala kindling in rats with brainstem bisection.

The effect of midsagittal bisection of the brainstem (the midbrain to the pons) on amygdala (AM) kindling at the primary and the secondary sites was examined in rats. It was found that the kindling rate was not affected at either primary or secondary sites regardless of the extent of bisection. However, seizure progression beyond stage 4 bilateral clonus did not occur with extensive dorsal bisection. The findings suggest that the dorsal midline brainstem structure bisected in this study participates in the mechanism of stage 5 seizure but is not involved in the transhemispheric positive transfer mechanism in rodent AM kindling.

Amygdala↗
PubMed1995

Effect of unilateral claustral lesion on intermittent light stimulation-induced convulsive response in D,L-allylglycine treated cats.

The effect of unilateral lesions of the claustrum was examined in cats treated with D,L-allylglycine. Prior to the lesion, intermittent light stimulation (ILS) induced (a) myoclonic jerking associated with generalized spike, or polyspike and wave discharge, maximal in the subcortical structures monitored and the cortical visual area, and (b) bisymmetrical generalized-onset tonic-clonic convulsions associated with sustained spike discharge in the motor cortex bilaterally. Subsequent to a unilateral lesion of the claustrum, ILS-induced electro-clinical manifestations of myoclonic jerking remained unchanged. However, the bisymmetrical convulsive pattern transformed into a partial onset secondarily generalized convulsive pattern beginning in the intact hemisphere. It is concluded that the claustrum plays an important role for access of visual afferents to the motor mechanism responsible for ILS-induced convulsive seizure.

Allylglycine↗
PubMed1995

Cingulate kindling in Senegalese baboons, Papio papio.

Kindling of the cingulate cortex in the Senegalese baboon Papio papio led to a protracted nonconvulsive seizure state characterized by immobile staring with (anterior cingulate, AC) or without (posterior cingulate, PC) widening of eyelids and neck flexion, followed by postictal visual searching behavior. Despite early bilateral spread of EEG discharges, ictal and interictal patterns remained persistently asymmetric. Secondary generalization was rapid and predictable once contralateral lower facial twitching associated with sustained adversion developed. After the primary site had been kindled, stimulation of the contralateral homotopic posterior cingulate cortex readily produced afterdischarge. However, it remained localized and kindling growth did not occur. The findings suggest that (a) the cingulate cortex can support nonconvulsive seizures; (b) cingulate seizures are accompanied by asymmetric convexity EEG discharges indicating its lateralized onset; (c) further evolution to convulsive seizures after kindling of cingulate cortex requires access to the ipsilateral frontocentral cortex responsible for facial twitching; and (d) the development of focal epileptogenesis at one cingulate site interferes with clinical seizure development at the homotopic contralateral site.

Adolescent↗
PubMed1995

Kindling of the interpeduncular nucleus and its influence on subsequent amygdala kindling in rats.

We examined the effect of interpeduncular nucleus (IPN) kindling on subsequent amygdala (AM) kindling in rats (n = 9). Eleven to 15 daily IPN stimulations at an afterdischarge (AD)-inducing threshold (400-1000 microA, biphasic sine waves, 1-3 s) produced progressive AD growth (9 of 9 rats) and recruitment of behavioral seizures (7 of 9 rats). The final form of the latter was generalized tonic-clonic seizures with or without a limbic seizure component. The latter was associated with ictal involvement of AM and sensorimotor cortex. Subsequent AM kindling resulted not only in more rapid kindling, but also in tonic seizure associated with a protracted loss of postural control (5-20 s) not observed in animals undergoing AM kindling without previous IPN kindling (n = 5). These findings indicate that the IPN can be kindled and that subsequent AM kindling utilizes the proconvulsant neuroplastic changes that have been already established by IPN kindling.

Amygdala↗
PubMed1993

Ipsilateral hemiconvulsive seizure after unilateral injection of procaine into the substantia innominata of amygdaloid-kindled rats.

The effects of procaine injected into the substantia innominata (SI) and the amygdala (AM) were compared in AM-kindled rats. Intra-SI injection of procaine (ipsilateral to the kindled AM) caused immediate contralateral hemiparesis lasting for about 30 min, associated with EEG amplitude reduction. When the kindled AM was stimulated at the previously established generalized seizure triggering threshold (GST), 8/15 animals had ipsilateral hemiconvulsive seizure 5 min after the injection. In all the animals, afterdischarge was readily produced with a significant reduction in its duration. When procaine was injected into the kindled AM, there was no paresis or EEG change. AM stimulation at the GST did not evoke afterdischarge 5 min after the injection, although the kindled seizure was reactivated by a more intense stimulus. After 24 hr, all the animals, regardless of the site of procaine injection, responded to GST stimulation with a kindled seizure. The data suggest that: (1) the effect of intra-SI procaine is not due to drug diffusion to the kindled AM, and (2) the kindled AM can gain access to the contralateral hemispheric motor mechanism without participation of the ipsilateral SI.

Amygdala↗
PubMed1993

The effect of brainstem bisection prior to the amygdala kindling in rats.

This study examined the effect of selective midline sagittal section of the brainstem prior to kindling of the amygdala (AM) in rats. The brainstem section did not affect the AM kindling development at the primary site. However, some of the animals with brainstem section showed an absence of positive transfer effect (PTE) at the secondary site. These findings suggest that the brainstem has a probable role in PTE of rat AM kindling.

Amygdala↗
PubMed1993

Dual task performance by patients with left or right speech dominance as determined by carotid amytal tests.

Patients who had their speech dominance determined by carotid Amytal testing were evaluated with a dual task procedure consisting of reading and finger tapping. As expected, the asymmetry of interference between tasks varied with speech dominance. Patients with left hemisphere speech tended to show greater interference in the right hand whereas patients with right hemisphere speech showed greater interference in the left hand. Since the right hemisphere dominant patients were also right-handed, the results suggest that interference effects are more closely linked to speech than to motor dominance.

Adolescent↗
PubMed1992

Convulsive seizures in rats induced by N-methyl-D-aspartate injection into the massa intermedia.

The behavioral and electroencephalographic effects of N-methyl-D-aspartate (NMDA, 25 nmol/1 microliter) injection into the massa intermedia (MI) was examined in rats. The injection caused violent running/jumping and shrill vocalization without evidence of EEG seizure in the hippocampus (HP) and amygdala (AM). Animals with the injection site located in the reuniens nucleus subsequently developed generalized tonic and then clonic seizure, leading to fatal status epilepticus in some animals. Intermittent or continuous EEG discharge in the limbic system was found during clonic seizures. These findings suggest that the NMDA receptor in the reuniens nucleus in the MI participates in the generation and expression of convulsive seizure in rats.

Animals↗