Distinct temporal patterns of electrical stimulation influence neural recruitment during PTZ infusion: An fMRI study

TY - JOUR

T1 - Distinct temporal patterns of electrical stimulation influence neural recruitment during PTZ infusion: An fMRI study

AU - Bernanos Soares Mesquita, Michel

AU - Medeiros, Daniel de Castro

AU - Cota, Vinicius Rosa

AU - Richardson, Mark P.

AU - Williams, Steven

AU - Dutra Moraes, Marcio Flavio

PY - 2011/3

Y1 - 2011/3

N2 - 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, 4 mg/ml/min) through an iv. catheter. Our results show that temporal lobe activation during ES-P or ES-NP did not present any statistical differences during ES. However, during vrz 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. (C) 2010 Elsevier Ltd. All rights reserved.

AB - 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, 4 mg/ml/min) through an iv. catheter. Our results show that temporal lobe activation during ES-P or ES-NP did not present any statistical differences during ES. However, during vrz 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. (C) 2010 Elsevier Ltd. All rights reserved.

U2 - 10.1016/j.pbiomolbio.2010.10.005

DO - 10.1016/j.pbiomolbio.2010.10.005

M3 - Literature review

VL - 105

SP - 109

EP - 118

JO - Progress in Biophysics and Molecular Biology

JF - Progress in Biophysics and Molecular Biology

IS - 1-2

ER -