Improvement in hippocampal kindling analysis through computational processing data / Aprimorando a análise do modelo de kindling hipocampal com o auxílio de processamento computacional

The kindling phenomenon is classically investigated in epileptology research. The present study aims to provide further information about hippocampal kindling through computational processing data. Adult Wistar rats were implanted with dorsal hippocampal and frontal neocortical electrodes to perform the experiment. The processing data was obtained using the Spike2 and Matlab softwares. An inverse relationship between the number of "wet dog shakes" and the Racine's motor stages development was found. Moreover it was observed a significant increase in the afterdischarge (AD) duration and its frequency content. The highest frequencies were, however, only reached at the beginning of behavioral seizures. During the primary AD, fast transients (ripples) were registered in both hippocampi superimposed to slower waves. This experiment highlights the usefulness of computational processing applied to animal models of temporal lobe epilepsy and supports a relevant role of the high frequency discharges in temporal epileptogenesis.

O fenômeno de kindling é classicamente utilizado no campo da epileptologia experimental. Este trabalho objetiva aprofundar a análise do modelo kindling hipocampal através de processamento computacional. Ratos wistar adultos receberam eletrodos hipocampais dorsais e neocorticais frontais para a realização do experimento. O processamento dos dados encontrados foi realizado pelos softwares Matlab e Spike2. Encontrou-se uma relação inversa entre wet dog shakes e o desenvolvimento dos estágios motores de Racine. A duração e o conteúdo de freqüência das pós-descargas hipocampais aumentaram durante o processo, sendo observadas descargas de alta freqüência (ripples) em ambos os hipocampos durante as pós-descargas primárias, superimpostas a ondas lentas. As mais altas freqüências, entretanto, foram apenas atingidas com o início das crises epilépticas. A utilização de sistemas computacionais para a confecção e análise do modelo de epilepsia temporal é ressaltada e reforça-se a relevância do papel das altas freqüências na epileptogênese temporal.

Hippocampal hyperexcitability facilitates amygdala kindling in rats.

BACKGROUND & OBJECTIVES: The amygdala and hippocampus are recognized as the two important structures in the brain involved in the development and control of kindled seizures. The study on the precise interconnection between these two regions can provide important insights into the functional anatomy of complex partial seizures. In this study the effect of an experimentally increased excitability in hippocampal neurons, via hippocampal kindling, on the amygdala kindling rate was investigated in rats. METHODS: Animals were divided into four groups. Tripolar electrodes were implanted in the amygdala and CA1 region of the dorsal hippocampus of animals of Groups 1, 3 and 4. In Group 2 animals, tripolar electrodes were only implanted in the amygdala. In Group 1, one week after surgery, the rats were kindled first from the hippocampus and the next day kindled by amygdala stimulation. In Groups 2 and 3, one week after surgery, rats were kindled from the amygdala. Group 4 animals had a recovery period of one week plus 32 days, which was the mean of the hippocampal kindling rate in Group 1, and then were kindled from the amygdala. RESULTS: In Group 1, the amygdala kindling rate (n; number of days for which animals were stimulated before a stage 5 motor convulsion is triggered) and seizure stage at day n/2 were significantly facilitated and increased respectively. There was also a significant positive correlation between hippocampal and amygdala kindling rates. INTERPRETATION & CONCLUSION: Results obtained show that an increase in hippocampal excitability can facilitate kindling from the amygdala. Thus, it is suggested that the hippocampus has an important role in the development and propagation of seizures from the amygdala.

Temperamento y personalidad en deficientes mentales / Temperament and personality in mental deficients

Se revisan los estudos sobre el temperamento y la personalidad de los deficientes mentales, se discute la hipótesis del déficit de inhibición y se estudia la aplicación de las dimensiones temperamentales básicas de extraversión y neuroticismo. Se concluye que no puede hablarse de un temperamento propio de los deficientes, puesto que se encuentra tanta variabilidad en el temperamento de los deficientes mentales como entre la población general; y que la consideración conjunta del temperamento, por un lado, y de la historia personal y la situación actual, por otro, permite dar cuenta, como en la población general, de las deficiencias individuales en los rasgos de personalidad de los deficientes mentales.

Psiquiatria pavloviana: a mobilidade cortical e as neuroses experimentais / Pavlov's psychiatry: the cortical mobility and the experimental neuroses

Ivan Petrovitch Pavlov (1849/1936), descobridor dos reflexos condicionados, demonstrou com suas experiências em animais que o córtex é um órgäo em permanente mobilidade graças às propriedades de irradiaçäo e concentraçäo dos processos fundamentais da atividade nervosa superior, a excitaçäo e a inibiçäo. Demonstrou, ainda, que cada ponto excitado cria uma área de inibiçäo nas regiöes vizinhas (induçäo negativa) e cada ponto inibido gera o fenômeno inverso na cortiça cerebral (induçäo positiva). O conjunto desta atividade foi denominado de induçäo recíproca, segundo a qual há uma delimitaçäo exata e minuciosa dos pontos excitados e inibidos. Durante as experiências era freqüente o aparecimento de transtornos funcionais da atividade normal dos hemisférios cerebrais, dando origem a novas investigaçöes que culminaram com o importante capítulo das neuroses experimentais, distúrbios patológicos que aparecem quando ultrapassados os limites da capacidade de trabalho da cortiça cerebral dos animais

Rapidly recurring cortical seizures induce changes in neuronal responsiveness to acetylcholine

La mayoría de los mecanismos propuestos para explicar la descarga epiléptica sugieren un excesivo influjo sináptico o posibles cambios en la excitabilidad celular que resultan en una disminución del umbral conculsivo y en la presencia de actividad autosostenida. Es probable que estos cambios sean causados por modificaciones en la sensibilidad de los receptores de membrana a un neurotransmisor específico. En vista de lo anterior, el objetivo del presente estudio ha sido evaluar la sensibilidad del receptor postsináptico por medio de la aplicación microiontoforética de sustancias cuyo efecto farmacológico es bien conocido, para determinar su posible participación en el proceso epiléptico. Se provocaron cambios en la excitabilidad cortical por estimulación eléctrica en la corteza sensoriomotora de ratas anestesiadas con uretano (1 g/kg intraperitoneal), inmovilizadas con bromuro de pancuronio y mantenidas con respiración mecánica. Los estímulos eléctricos consistieron en trenes de pulsos bifásicos, cada uno con duración de un milisegundo con frecuencia de 100 pps y con duración del tren de 1 segundo. La respuesta de la neurona a la acetilcolina fue evaluada antes y después que se establecieron las descargas. La dosis se midió en monoampres de corriente microiontoforética. Los potenciales del campo extracelular se registraron con el barril central de micropipetas. Los barriles periféricos fueron usados para aplicaciones iontoforéticas de acetilcolina (Ach .1, 1M), atropina (25 mM). Uno de estos barriles conteniendo NaCl (2M) se empleó para el paso automático de corriente de balance; para 613 de estas células las descargas ya estaban establecidas; en las restantes 532 células, la corteza fue normal (sin descargas). Un aumento en la frecuencia promedio de descarga celular se obsevó después de la aplicación iontoforética de Ach. Intensidades de 2 a 50 nA de corriente se emplearon en la corteza con descargas establecidas. En la corteza con descargas no establecidad la respuesta celular a la aplicación de Ach fue menor cuando fueron aplicadas corrientes de igual intensidad. En ambas cortezas, las células respondieron con mucha menor intensidad a la aplicación de NaCl con corriente de magnitud similar a la usada para movilizar la Ach. Estos hallazgos muestran un cambio en la excitabilidad celualr que se refleja en un nivel más elevado de respuesta celular cuando la acetilcolina está presente, y sugieren que este neurotransmisor participa en el mecanismo de la epilep

Antiepileptic effects of cerebellar nucleus dentatus electrical stimulation under different conditions of brain epileptisation.

It was shown in acute experiments on cats that high frequency (100-300 Hz) electrical stimulation of dentate nucleus led to the solitary epileptic foci of relatively weak intensity suppression and at the same time caused the activation of stronger focal epileptic activity. Electrical stimulation of nucleus dentatus suppressed the epileptic activity of grand mal type and increased seizures in rats with petit mal form of epileptogenesis which was formed in rats during pentylenetatiozol kindling. It was concluded that there is a relation between the antiepileptic effects of nucleus dentatus irritation and intensity as well as the form of epileptic activity induced experimentally.

Bilateral microinjection of ethosuximide into the substantia nigra does not prevent amygdala-kindled seizures

Male Wistar rats were sugjected to daily sessions of electrical amygdala kindling until a generalized seixure was observed on five consecutive days. Bilateral microinections (0.5 micronl) of ethosuximide (ETX) (10 pg/micronl) or saline were then administered though guide cannulas into the substantia nigra (pars reticulata). No significant difference was observed between the ETX (N = 8) and saline (N = 8) groups in duration of afterdischarge or in the latency for stage 5 generalized seizures. Our results indicate that ETX applied to the substantia nigra is not effective in suppressing amydala-kindled seizure

Influences of vestibulo-cerebellum on kindling in the cat.

The development of amygdaloid kindling was assessed under conditions of pharmacological depression of the nodular areas of vestibulocerebellum and also following vestibular stimulation in chronically prepared cats. The results demonstrated that a single intra-nodular micro-injection of procaine hydrochlorides could significantly facilitate such epileptogenesis for at least several days. The number of kindling trials required to reach the first generalized convulsions was significantly increased by natural vestibular stimulation in comparison with control kindled animals. The intensity of fit, development of amygdaloid seizures and the convulsions were reduced markedly within a week by pre-conditioning the kindled animals with daily vestibular stimulation for 15-30 min. In addition, analysis of the behaviour of sleep-wake cycle indicated a significant increase in total sleep time and in the percentage of rapid eye movement (REM) sleep. These findings suggest that the natural rotational vestibular stimulation may result in a durable modification of brain function through development of enduring focal sensitization of catecholamine-mediated inhibitory mechanisms, reflecting the tonic inhibitory influences of the vestibulo-cerebellum in regulating the development and attenuation of epileptic states.

Aspectos fisiológicos da sexualidade humana / Physiological aspects of human sexuality

O autor procura divulgar os aspectos gerais da sexualidade humana enfocando as fases básicas de Excitaçäo - Planalto - Orgasmo e Relaxamento. O fator sistema nervoso, especialmente o sistema límbico, e o fator hormonal säo tambem comentados, em face de sua importância