Analyse de l'activité électrique multi-sites du cortex auditif chez le cobaye
Camilo La Rota · HAL (Le Centre pour la Communication Scientifique Directe) · 2003
The scientific problem that has motivated this study is the representation and processing of information in the neocortex. We are interested in particular in the hypothesis that states that information is coded on the neural populations' cooperative activities. This study is essential to find technological solutions to some medical problems, such as the development of neuroprosthesis. The existence of new multisite measuring techniques that allow the in vivo observation of the spatiotemporal activity of the cortex at high resolutions, give us the possibility to study the concept of “neural interaction” at mesoscopic scales and to study the mechanisms of senses and perception at the level of functional areas. We have studied in particular the electrical activity of the guinea pig's auditory cortex in response to stimuli using voltage-dependent dyes (optical imaging). We have studied some techniques for the processing and analysis of the spatiotemporal information represented by this data. By means of a descriptive analysis we have characterized the signals, their variability and the measuring errors. A theoretical study complemented this description, and allowed us to interpret our data in function of the underlying neural activity. Optical signals are difficult to process with traditional signal processing techniques, we have used wavelet based techniques to estimate and characterize the neural activity components of the signal. Finally, we have evaluated some approaches to the spatiotemporal modeling of the cortical activity, and we have studied the pertinence of these models to describe our data. Some perspectives on this problem and on the design of future experiences are given.