RESUMO
Se usa el término «oscilación o actividad oscilatoria» para referirse a las fluctuaciones rítmicas de los potenciales postsinápticos de un grupo neuronal (potenciales de campo local) o de una región cortical (EEG, electrocorticografía) y también al patrón de descarga rítmico de los potenciales de acción de una neurona o un grupo neuronal. La actividad oscilatoria posibilita la sincronización entre grupos neuronales de la misma área cortical o de áreas distantes entre sí que intervienen en una acción motora, tarea cognitiva o perceptiva. Con frecuencia es motivo de confusión asociar la presencia de actividad oscilatoria con fenómenos de sincronización, ya que ambos fenómenos aunque relacionados no son equivalentes. En patologías neurológicas o psiquiátricas tan distintas como la enfermedad de Parkinson u otros movimientos anormales, la epilepsia o la esquizofrenia se han descrito anomalías de la actividad oscilatoria de distintas estructuras cerebrales o de su sincronización que podrían jugar un papel relevante en su fisiopatología. En esta revisión se discuten estos aspectos haciendo hincapié en su importancia por ser un mecanismo básico del funcionamiento cerebral y un nuevo mecanismo fisiopatólogico de la sintomatología de algunas enfermedades cerebrales (AU)
The terms «oscillations» or «oscillatory activity» are frequently used not only to define the rhythmic fluctuations of the postsynaptic potentials of a neuronal group (local field potentials) or a cortical region (EEG, MEG), but also to indicate the rhythmic discharge pattern of action potentials from a neuron or a small group of neurons. Oscillatory activity makes possible the synchronization of different neuronal groups from nearby or distant cortical regions that participate in the same motor, sensory or cognitive task. The presence of oscillatory activity is usually associated to the existence of synchronization, but both phenomena are not necessarily always equivalent. Abnormalities of oscillatory activities or synchronization within or between different brain structures have been described in several neurological and psychiatric diseases; these abnormalities might play a relevant pathophysiological role in Parkinson´s disease (and other movement disorders), schizophrenia or epilepsy. This review discusses all these aspects, with emphasis on their potential role both as a basic mechanism in brain function and as a pathophysiological substrate for some of the symptoms and signs observed in several diseases (AU)
Assuntos
Humanos , Masculino , Feminino , Técnicas de Diagnóstico Neurológico , Doenças do Sistema Nervoso/fisiopatologia , Gânglios da Base/fisiopatologia , Gânglios da Base/efeitos da radiação , Doença de Parkinson/diagnóstico , Doença de Parkinson/fisiopatologia , Doença de Parkinson , Doença de Parkinson Pós-Encefalítica/fisiopatologia , Epilepsia/fisiopatologia , Esquizofrenia/fisiopatologia , Neurociências/métodos , Neurociências/normas , Neurociências/tendências , Hipocinesia/fisiopatologiaRESUMO
Biomaterial pieces with osteogenic properties, suitable for use in the treatment of bone defects, were synthesized. The materials, which avoid bone infections, are exclusively composed of gentamicin sulfate and bioactive SiO2-CaO-P2O5 sol-gel glass (synthesized previously), and were manufactured by means of uniaxial and isostatic pressure of the mixed components. After implanting the pieces into rabbit femur, we studied (1) antibiotic release, determining the concentration in proximal and distal bone, liver, kidney, and lung as a function of time, and (2) bone growth as a consequence of the glass reactivity in the biological environment. The results demonstrated that the implants are good carriers for local gentamicin release into the local osseous tissue, where they show excellent biocompatibility and bone integration. Moreover, these implants are able to promote bone growth during the resorption process.
