The sleep-wakefulness cycle of Wistar rats with spontaneous absence-like epilepsy / O ciclo vigília-sono de ratos Wistar portadores de epilepsia espontânea tipo ausência

Possible interactions between the sleep-wakefulness cycle and a new kind of spontaneous epilepsy, expressed as absence-like seizures and spike-wave bursts in FMUSP rats, are evaluated. The electro-oscillograms of some cortical and subcortical regions of the brain were recorded, as well as head, rostrum/vibrissae and eye movements. Recordings were performed uninterruptedly during 24 hours. The seizures were mostly concentrated in the wakefulness state but they could occur in any other phase, including paradoxical sleep. After the seizure, the rats usually returned to the same phase that was interrupted, although they often returned to wakefulness. There was an intense fragmentation of the sleep-wakefulness cycle. The incidence of each cycle phase was significantly reduced, except SIII of synchronized sleep and paradoxical sleep, thus maintaining the overall duration and architecture of the sleep-wakefulness cycle. The fragmentation of the cycle seems to be due to an impairment of the very processes that generate sleep and wakefulness. Electrophysiological and behavioral profiles of the FMUSP rats recommend accurate and comprehensive study of the animal model owing to its resemblance to seizures in humans and also to discrepancies with existing genetic or experimental epilepsy models.(AU)

A razão principal desta investigação foi estudar a arquitetura do ciclo vigília-sono numa cepa de ratos Wistar (FMUSP-rats) portadores de epilepsia espontânea tipo ausência. Foram utilizados 10 ratos Wistar adultos, que receberam eletrodos em regiões corticais e subcorticais, nos músculos trapézios e nos epicantos oculares, pelos quais registramos os eletroscilogramas continuamente por 24 horas, dos quais foram analisados os registros eletroscilográficos e demais parâmetros da arquitetura do ciclo vigília-sono. As crises ocorriam preferencialmente durante o período escuro, coincidindo com a maior prevalência de estados de vigília. O ciclo vigília-sono sofreu intensa fragmentação nos ratos epilépticos, e a duração média de algumas fases do sono foi mais prolongada nos ratos epilépticos do que nos sadios. As manifestações eletrofisiológicas das crises assumiram várias formas, predominando, porém, os complexos espícula-onda (de 7 a 9,5 Hz) o que se assemelha muito à faixa de oscilação das ondas teta. As características eletrofisiológicas e comportamentais da epilepsia que estudamos recomendam o estudo acurado e abrangente desse modelo de síndrome epiléptica, por sua semelhança com as crises encontradas em humanos, mas também por algumas discrepâncias em relação a modelos de epilepsia genética ou experimental já existentes.(AU)

Spontaneous absence-like activity in Wistar rats: Behavioral and electrographic characteristics and the effects of antiepileptic drugs / Atividade epiléptica espontânea tipo ausência em Ratos Wistar: características eletrográficas e comportamentais e os efeitos de drogas antiepilépticas

Current investigation describes the behavioral and electrographic characteristics of spontaneous absence-like seizures identified in Wistar rats (referred to here as FMUSP-rats, after the Faculty of Medicine, University of São Paulo, São Paulo State, Brazil), and characterized by spike-wave discharges (SWDs) in the neocortex and the hippocampus. After consanguineous crossing directed to an increased incidence of seizures, the latter were observed in almost all F9 offspring. FMUSP-rat seizures are expressed as immobility and concomitant SWDs, oscillating between 7.5 and 12 Hz in the frontoparietal cortex and the hippocampus. Behaviorally, they are mainly associated with clonic movements of the eyes, rostrum and vibrissae, the latter ranging between 1 and 70 seconds and occur at a rate of up to 229 per hour. Systemic injections of ethosuximide (0, 25, 50, 100, 250 mg kg-1) and of diazepam (15 mg kg-1) increased the latency for the first seizure and reduced both the hourly incidence of SWD bursts and their mean duration. Carbamazepine (30 mg kg-1) injections increased both the incidence and duration of the SWDs, leaving the latency for the first seizure unchanged. Comparisons between FMUSP-rats and well-established genetic models of absence seizures data indicated that the animals described herein might contribute towards studies on the neurological condition under analysis.(AU)

Neste estudo, descrevemos aspectos eletrográficos e comportamentais de atividade semelhante às crises de ausência identificadas em ratos Wistar (ratos FMUSP - Faculdade de Medicina da Universidade de São Paulo, Estado de São Paulo, Brasil), que são caracterizadas por descargas em forma de espícula-onda no neocórtex e no hipocampo em 100% dos ratos da geração F9 resultante de cruzamentos consanguíneos. As crises se manifestaram com imobilidade comportamental associada com atividade eletrográfica em forma de espícula-onda oscilando entre 7,5 e 12 Hz no córtex frontoparietal e no hipocampo. Também foram observados comportamentos associados como clonias oculares, rostrais e de vibrissa que duravam de 1 a 70 segundos podendo ocorrer a uma taxa de até 229 eventos por hora. Injeçõe sistêmicas de etosuximida (0, 25, 50, 100 e 250 mg kg-1) and of diazepam (15 mg kg-1) aumentaram a latência para a primeira crise e reduziram tanto a incidência quanto a duração das crises. Injeções de Carbamazepina (30 mg kg-1) aumentaram tanto a incidência quanto a duração das crises sem interferir na latência. Comparações feitas entre os ratos epilépticos FMUSP com os modelos genéticos de epilepsia bem estabelecidos na atualidade indicaram que o modelo aqui descrito pode contribuir para um melhor entendimento dos mecanismos relacionados a esta condição neurológica.(AU)

Spontaneous absence-like activity in Wistar rats: Behavioral and electrographic characteristics and the effects of antiepileptic drugs / Atividade epiléptica espontânea tipo ausência em Ratos Wistar: características eletrográficas e comportamentais e os efeitos de drogas antiepilépticas

Current investigation describes the behavioral and electrographic characteristics of spontaneous absence-like seizures identified in Wistar rats (referred to here as FMUSP-rats, after the Faculty of Medicine, University of São Paulo, São Paulo State, Brazil), and characterized by spike -wave discharges (SWDs) in the neocortex and the hippocampus. After consanguineous crossing directed to an increased incidence of seizures, the latter were observed in almost all F9 offspring. FMUSP-rat seizures are expressed as immobility and concomitant SWDs, oscillating between 7.5 and 12 Hz in the frontoparietal cortex and the hippocampus. Behaviorally, they are mainly associated with clonic movements of the eyes, rostrum and vibrissae, the latter ranging between 1 and 70 seconds and occur at a rate of up to 229 per hour. Systemic injections of ethosuximide (0, 25, 50, 100, 250 mg kg-1) and of diazepam (15 mg kg-1) increased the latency for the first seizure and reduced both the hourly incidence of SWD bursts and their mean duration. Carbamazepine (30 mg kg-1) injections increased both the incidence and duration of the SWDs, leaving the latency for the first seizure unchanged. Comparisons between FMUSP-rats and well-established genetic models of absence seizures data indicated that the animals described herein might contribute towards studies on the neurological condition under analysis.

Neste estudo, descrevemos aspectos eletrográficos e comportamentais de atividade semelhante às crises de ausência identificadas em ratos Wistar (ratos FMUSP - Faculdade de Medicina da Universidade de São Paulo, Estado de São Paulo, Brasil), que são caracterizadas por descargas em forma de espícula-onda no neocórtex e no hipocampo em 100% dos ratos da geração F9 resultante de cruzamentos consanguíneos. As crises se manifestaram com imobilidade comportamental associada com atividade eletrográfica em forma de espícula -onda oscilando entre 7,5 e 12 Hz no córtex frontoparietal e no hipocampo. Também foram observados comportamentos associados como clonias oculares, rostrais e de vibrissa que duravam de 1 a 70 segundos podendo ocorrer a uma taxa de até 229 eventos por hora. Injeçõe sistêmicas de etosuximida (0, 25, 50, 100 e 250 mg kg-1) and of diazepam (15 mg kg-1) aumentaram a latência para a primeira crise e reduziram tanto a incidência quanto a duração das crises. Injeções de Carbamazepina (30 mg kg-1) aumentaram tanto a incidência quanto a duração das crises sem interferir na latência. Comparações feitas entre os ratos epilépticos FMUSP com os modelos genéticos de epilepsia bem estabelecidos na atualidade indicaram que o modelo aqui descrito pode contribuir para um melhor entendimento dos mecanismos relacionados a esta condição neurológica.

Time-related effects of general functional training in spinal cord-injured rats.

OBJECTIVES: This prospective, randomized, experimental study with rats aimed to investigate the influence of general treatment strategies on the motor recovery of Wistar rats with moderate contusive spinal cord injury. METHODS: A total of 51 Wistar rats were randomized into five groups: control, maze, ramp, runway, and sham (laminectomy only). The rats underwent spinal cord injury at the T9-T10 levels using the NYU-Impactor. Each group was trained for 12 minutes twice a week for two weeks before and five weeks after the spinal cord injury, except for the control group. Functional motor recovery was assessed with the Basso, Beattie, and Bresnahan Scale on the first postoperative day and then once a week for five weeks. The animals were euthanized, and the spinal cords were collected for histological analysis. RESULTS: Ramp and maze groups showed an earlier and greater functional improvement effect than the control and runway groups. However, over time, unexpectedly, all of the groups showed similar effects as the control group, with spontaneous recovery. There were no histological differences in the injured area between the trained and control groups. CONCLUSION: Short-term benefits can be associated with a specific training regime; however, the same training was ineffective at maintaining superior long-term recovery. These results might support new considerations before hospital discharge of patients with spinal cord injuries.

Time-related effects of general functional training in spinal cord-injured rats

OBJECTIVES: This prospective, randomized, experimental study with rats aimed to investigate the influence of general treatment strategies on the motor recovery of Wistar rats with moderate contusive spinal cord injury. METHODS: A total of 51 Wistar rats were randomized into five groups: control, maze, ramp, runway, and sham (laminectomy only). The rats underwent spinal cord injury at the T9-T10 levels using the NYU-Impactor. Each group was trained for 12 minutes twice a week for two weeks before and five weeks after the spinal cord injury, except for the control group. Functional motor recovery was assessed with the Basso, Beattie, and Bresnahan Scale on the first postoperative day and then once a week for five weeks. The animals were euthanized, and the spinal cords were collected for histological analysis. RESULTS: Ramp and maze groups showed an earlier and greater functional improvement effect than the control and runway groups. However, over time, unexpectedly, all of the groups showed similar effects as the control group, with spontaneous recovery. There were no histological differences in the injured area between the trained and control groups. CONCLUSION: Short-term benefits can be associated with a specific training regime; however, the same training was ineffective at maintaining superior long-term recovery. These results might support new considerations before hospital discharge of patients with spinal cord injuries.

On the functional role of consciousness

Organization of behavior is grounded on several stages of processing of information by the nervous system. Identification is one of such stages. Through identitication the original information, generated in sensory, automatic, mnemonic and volitional systems, acquires meaning. As one among other forms of identification of neural information the conscious process ensues the original event and precedes decision, organization and effectuation of the activity of the nervous system expressed as behavior. Awareness (that is so characteristic of mental activity during wakefulness), pathological hallucinations, dreaming and other forms of perceptive recognition of neural information always result in some particular pattern of behavion The conscious process, therefore, is neither an epiphenomenon with no ascribable function, nor a nonspecific, passive by-product of neural activity which just "watches" what is going on inside and outside of the body. It is neither an initial nor a final stage in organization of behavior but a specific, highly precise intermediate stage, a particular modality of neural processing which plays a definite function in such organization.