Transcranial static magnetic stimulation reduces seizures in a mouse model of Dravet syndrome.

Dravet syndrome is a rare form of severe genetic epilepsy characterized by recurrent and long-lasting seizures. It appears around the first year of life, with a quick evolution toward an increase in the frequency of the seizures, accompanied by a delay in motor and cognitive development, and does not respond well to antiepileptic medication. Most patients carry a mutation in the gene SCN1A encoding the α subunit of the voltage-gated sodium channel Nav1.1, resulting in hyperexcitability of neural circuits and seizure onset. In this work, we applied transcranial static magnetic stimulation (tSMS), a non-invasive, safe, easy-to-use and affordable neuromodulatory tool that reduces neural excitability in a mouse model of Dravet syndrome. We demonstrate that tSMS dramatically reduced the number of crises. Furthermore, crises recorded in the presence of the tSMS were shorter and less intense than in the sham condition. Since tSMS has demonstrated its efficacy at reducing cortical excitability in humans without showing unwanted side effects, in an attempt to anticipate a possible use of tSMS for Dravet Syndrome patients, we performed a numerical simulation in which the magnetic field generated by the magnet was modeled to estimate the magnetic field intensity reached in the cerebral cortex, which could help to design stimulation strategies in these patients. Our results provide a proof of concept for nonpharmacological treatment of Dravet syndrome, which opens the door to the design of new protocols for treatment.

Electrical activity in primary visual area due to interocular suppression.

Under binocular rivalry conditions, evoked potentials to lower hemifield stimulation are more positive for the dominant than for the suppressed eye between 100 and 300 ms. However, this pattern reverses when the upper hemifield is stimulated, suggesting a neural source in V1 for this endogenous potential (rivalry-related potential, RRP). Here we investigated the functional significance of the RRP using an interocular suppression procedure. We replicated the RRP polarity reversal for upper versus lower hemifield stimulation and showed that the RRP reflects differences in processing during dominance and suppression and not shifts in dominance.

Psychophysiological studies of unattended information processing.

The article describes the general methods and some of the results obtained in the Psychophysiology Laboratory of the University of La Coruña. The paper covers our research on the Simon effect and accessory effect, although it is not a review of the literature. The research strategy we followed is built around the use of lateralized motor potentials recorded from scalp. These measures allow observing the way responses are selected and when they are selected, providing an invaluable tool to study response interference and to split reaction time into two halves. The research on the Simon effect concludes that interference during response selection is critical in the Simon effect but it is dubious whether this process should be considered as automatic and stimulus-driven, as is widely accepted. The experiments with the accessory effect indicate that facilitation is produced before response selection is over, which ends a long controversy about the locus of the accessory effect.

Early visual processing during binocular rivalry studied with visual evoked potentials.

Visual evoked potentials (VEPs) were recorded to probes presented to the dominant and suppressed eyes in a binocular rivalry paradigm. Probes presented to the suppressed eye interrupted the current dominance phase and produced a P300-like deflection (400-700 ms). Probes delivered to the dominant eye increased the duration of the current dominance phase. VEPs to these probes included an endogenous component that overlapped the early exogenous components. The early endogenous component (rivalry-related potential, RRP) started as early as 70 ms and had a broad centroparietooccipital distribution.