Novel Stimulation Protocols based on Phase Resetting Principles: Applications to Magnetoencephalography and Deep Brain Stimulation

Recently, stimulation techniques have been developed which enable one to reliably manipulate synchronization processes between and within oscillatory neuronal populations by means of a coordinated reset of neuronal sub-populations [1, 2]. In addition, a stochastic phase resetting analysis has been developed which makes it possible to detect the corresponding complex responses and transient synchronization and desynchronization processes in experimental data [3]. The talk presents two applications: (i) Visual stimulation in humans: In a full-field pattern reversal task we studied transient synchronization and desynchronization between visual areas V1 and V5 in eight healthy subjects with magnetoencephalography [5, 6]. We observed cross-trial (CT) response clustering (i.e., a switching between qualitatively different responses across trials [1, 3]) in V1 and/or V5 in all subjects. Our approach shows that, apart from a simple early reset, the visual stimulus causes long-lasting (>2s) coordinated responses in V1 and V5 which escape detection with standard averaging. (ii) Deep brain stimulation (DBS): permanent DBS at high frequencies turned out to be the standard therapy for patients suffering from neurological diseases (e.g., Parkinson's disease and essential tremor) who do not respond to drug therapy [7]. Standard DBS appears to basically suppress the neuronal firing in relevant target areas. It may cause side effects and its therapeutic effect may vanish in the course of the therapy. To develop milder and more effective DBS techniques, we have applied the novel stimulation methods [2] to 4 tremor patients during electrode implantation. The novel stimulation protocols desynchronize the neuronal firing in the target areas. In all 4 patients the coordinated reset suppressed the peripheral tremor, even if the standard DBS was not effective [4]. References: [1] Tass PA. Phys Rev E 2003; 67: 051902. [2] Tass PA. Biol Cybern 2003; 89: 81–88. [3] Tass PA. Phys Rev E 2004; 69: 051909. [4] Tass PA et al. submitted. [5] Barnikol UB et al. in preparation. [6] Tass PA et al. in preparation. [7] Benabid AL et al. The Lancet 1991; 337: 403–406.