[Temporal spectral evolution of electroencephalogram. Methodology and applications].

INTRODUCTION

The event related potentials (ERPs) allow to study the evolution of the cerebral electric activity related with the diverse sensorial, motors and cognitive processes. However, the ERPs and the spectral analyses based in Fast Fourier Transform, are not able to show the variations along the time of the spectral content of the electroencephalogram (EEG).

OBJECTIVE

The present work will show the necessary methodology to obtain the temporal dynamics of the frequency (TSE) in the EEG, a technique described by Salmelin and Hari (1994) that allows the analysis of the modulations of any spectral band along the time.

SUBJECTS AND METHODS

The presented data correspond to the electroencephalographic registration of 20 human subjects during an experiment of visual spatial attention.

RESULTS

The modulations of the ERPs differ of the observed by the spectral techniques in latency and topography. Likewise, comparing different spectral techniques is proven that the TSE allows to define with more temporal precision the variations on the spectral content.

CONCLUSION

The application of the TSE technique to the same EEG signal that is used for obtaining the ERPs, allows the inclusion of the variable time in the spectral analysis of the EEG, what can be crucial to understand the physiological bases of some neuropathologies.