Background Vagus nerve stimulation (VNS) is an approved treatment for epilepsy and has been investigated in clinical trials of depression. Little is known about the relationship of VNS parameters to brain function. Using the interleaved VNS /functional magnetic resonance imaging (fMRI) technique, we tested whether variations of VNS pulse width (PW) would produce different immediate brain activation in a manner consistent with single neuron PW studies. Methods Twelve adult patients with major depression, treated with VNS, underwent three consecutive VNS/fMRI scans, each randomly using one of three PWs (130 μs, 250 μs, or 500 μs). The data were analyzed with SPM2. Results Global activations induced by PWs 250 and 500 were both significantly greater than that induced by PW 130 but not significantly different from each other. For global deactivation, PWs 130 and 250 were both significantly greater than PW 500 but not significantly different from each other. Regional similarities and differences were also seen with the various PWs. Conclusions The data confirm our hypothesis that VNS at PW 500 globally produces no more activation than does PW 250, and PW 130 is insufficient for activation of some regions. These data suggest that PW is an important variable in producing VNS brain effects.
Bibliographical noteFunding Information:
This study was funded, in part, by Grants from the Charles A. Dana Foundation and Cyberonics (DEB). The Brain Stimulation Laboratory is also supported, in part, by research Grants from the Defense Advanced Research Projects Agency, the Stanley Foundation, the National Alliance for Research on Schizophrenia and Depression, the Borderline Personality Disorders Foundation, and National Institute of Neurological Disorders and Stroke Grant RO1-AG40956.
Aspects of this work were presented at the Society of Biological Psychiatry Annual Convention, May 17, 2003, San Francisco, California. The conference was sponsored by the Society of Biological Psychiatry.
- Functional magnetic resonance imaging
- Pulse width
- Vagus nerve stimulation