RESUMO
A successful therapy requires an understanding and investigation of the aetiology of a disease. Psychiatric diseases represent a special challenge, because environmental factors may play a crucial role in their development as well as possible physiological and genetic causes. Therefore, epigenetics has established itself to be a branch of research that studies the effect of environmental factors on the development of psychiatric diseases, leading to promising new approaches for diagnosis and therapy.
Assuntos
Epigênese Genética/fisiologia , Transtornos Mentais/genética , Transtornos Mentais/psicologia , Psiquiatria/tendências , Alcoolismo/genética , Alcoolismo/psicologia , Transtorno Autístico/genética , Transtorno Autístico/psicologia , Transtorno Depressivo/genética , Transtorno Depressivo/psicologia , Interação Gene-Ambiente , Humanos , Transtornos Mentais/diagnóstico , Transtornos Mentais/terapia , Natureza , Esquizofrenia/genética , Psicologia do Esquizofrênico , Meio Social , Transtornos de Estresse Pós-Traumáticos/genética , Transtornos de Estresse Pós-Traumáticos/psicologiaRESUMO
Single-neuron recordings have shown that the posterior parietal cortex (PPC) processes spatial information in many frames of reference, including gaze-centered, head-centered, body-centered, and intermediate coding frames. At the population level, rhythmic neuronal synchronization may provide a mechanism by which PPC could selectively emphasize the task-relevant reference frame in spatial processing. Using magnetoencephalography, we tested this hypothesis by studying the modulations in oscillatory activity in a spatial updating task. Human subjects had to remember the location of a target, briefly flashed left or right of central fixation. Next, they refixated and then, after a further memory delay, made a saccade to the memorized target location. We observed gamma-band (>40 Hz) synchronization and alpha-band (8-12 Hz) desychronization in contralateral occipital and parietal areas, both showing updating in a gaze-centered reference frame but with fast and slow time courses, respectively. Furthermore, after updating, ipsilateral areas showed less alpha desynchronization when they had been contralateral to the target before updating. Taken together, our results suggest that power in the gamma band is instantly reorganized to encode task-relevant visuomotor space in a gaze-centered reference frame, while power in the alpha band reflects a regulatory mechanism actively facilitating the gating of the saccade target and inhibiting the original stimulus representation.
Assuntos
Mapeamento Encefálico , Lobo Parietal/fisiologia , Percepção Espacial/fisiologia , Adulto , Feminino , Humanos , Magnetoencefalografia , Masculino , Estimulação Luminosa , Movimentos Sacádicos/fisiologia , Processamento de Sinais Assistido por ComputadorRESUMO
Neuropsychological and neuroimaging studies have implicated the human posterior parietal cortex (PPC) in sensorimotor integration and saccade planning. However, the temporal dynamics of the underlying physiology and its relationship to observations in non-human primates have been difficult to pin down. Here we review some recent work that investigates the role of human parietal neuronal synchronization in the coding and updating of visuomotor representations in saccade and anti-saccade tasks. We also discuss this work in relation to findings made on different spatial and temporal scales in monkey and human posterior parietal cortex.
