A New Procedure to Discriminate and Study Different Rhythmical Cortical Activities on the Basis of their Responsiveness to Simple Sensory Stimulation

The investigation of the spontaneous as well as stimulus related rhythmical brain activities has been receiving increasing attention in the recent years. Cognitive functions as well as arise of pathologies, have been correlated with time and frequency behaviour of cortical rhythms [1]–[9]. However the understanding of such correlations and of the genesis of the rhythms is still in a primitive stage. The erratic behaviour of the power of most of the spontaneous rhythms, appearing in spindles at random instants, and the quite large inter-individual variability caused difficulties when investigating such correlations or looking for functional and/or pathological indicators. Moving from the observation that those brain structures generating spontaneous oscillations have higher responsiveness to sensory stimulation in the same frequency band where such oscillations are detected [10]. we propose to classify the activities on the basis of their degree of responsiveness to rhythmic sensory stimulation. Here we present a procedure able to discriminate these activities within the a band on such basis.