Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8401576 | Progress in Biophysics and Molecular Biology | 2011 | 10 Pages |
Abstract
Our working hypothesis is that constant inter-pulse interval (IPI) electrical stimulation (ES) would resonate with endogenous epileptogenic reverberating circuits, favoring seizure, while random inter-interval ES protocol would promote desynchronization of such neural networks, interfering with the abnormal recruitment of neural structures. Male Wistar rats were stereotaxically implanted with a monopolar ES carbon-fiber electrode (minimizing fMRI artifact) in the amygdala. A 7T fMRI scanner was used to evaluate brain activity during ES, fixed four pulses per second ratio, using either a periodic IPI (ES-P) or random IPI (non-periodic ES-NP) stimulation paradigm. Appropriate imaging protocols were used to compare baseline BOLD (blood oxygen level dependent) MRI with scans during ES. A second series of experiments, both without stimuli and under the same ES paradigms, were evaluated during continuous infusion of pentylenetetrazole (PTZ, 4Â mg/ml/min) through an i.v. catheter. Our results show that temporal lobe activation during ES-P or ES-NP did not present any statistical differences during ES. However, during PTZ infusion, PTZ-P facilitated recruitment of the temporal lobe ipsilateral to ES while PTZ-NP showed significantly less activation ipsilateral to ES and, in turn, less inter-hemispheric differences. Altogether, our results support the hypothesis of reverberating circuits being synchronized by ES-P and desynchronized by ES-NP. Time-coded low frequency stimulation may be an interesting alternative treatment for patients with refractory epilepsy.
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Authors
Michel Bernanos Soares Mesquita, Daniel de Castro Medeiros, VinÃcius Rosa Cota, Mark P. Richardson, Steven Williams, Márcio Flávio Dutra Moraes,