Journal of neuroscience methods
-
J. Neurosci. Methods · Mar 2010
Semi-automatic stereotactic coordinate identification algorithm for routine localization of Deep Brain Stimulation electrodes.
Deep Brain Stimulation (DBS) is a routine therapy for movement disorders, and has several emerging indications. We present a novel protocol to define the stereotactic coordinates of metallic DBS implants that may be routinely employed for validating therapeutic anatomical targets. Patients were referred for troubleshooting or new DBS implantation. ⋯ The median and mean Euclidean distance errors for automatic identification of electrode locations were 0.20mm and 0.22 mm, respectively. This method is an accurate method of localization of active DBS contacts within the sub-cortical region. As the investigational indications of DBS expand, this method may be used for verification of final implant coordinates, critical for understanding clinical benefit and comparing efficacy between subjects.
-
J. Neurosci. Methods · Feb 2010
Development of animal model for vasculatic neuropathy: Induction by ischemic-reperfusion in the rat femoral artery.
Ischemic-reperfusion (I/R) is common in various pathological conditions like diabetic complication, complex regional pain syndrome type II (CRPS II), necrotizing vascular occlusive disease and trauma. We have developed an animal model of ischemic-reperfusion injury induced nociceptive sensory neuropathy in rats. The model was validated after 2, 4 and 6h of ischemia followed by prolonged reperfusion. ⋯ Histopathological study had revealed the decrease in nerve fiber density in the moderate and severe I/R groups. We selected the moderate (4h) ischemic-reperfusion injury as beneficial model because of the good correlation with clinical status for the development of neuropathy in human associated with severe pain disorders. This model can be used to explore pathophysiological mechanisms implied in the genesis of neuropathic pain and also to evaluate the new analgesic agents, peripheral neuro-vasoactive substances and neuroprotective drugs.
-
J. Neurosci. Methods · Feb 2010
Correction of low-frequency physiological noise from the resting state BOLD fMRI--Effect on ICA default mode analysis at 1.5 T.
Confounding low-frequency fluctuation (LFF) physiological noise is a concern for functional connectivity analyses in blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI). Using estimates of LFF physiological noise derived from measured cardiac and respiration signals, noise can be filtered from the time series thus improving the results of functional connectivity analysis. The ability of spatial independent component analysis (ICA) to separate LFF physiological noise from the default mode network (DMN), which overlap each other spatially and occur at similar frequencies, has remained an open question. ⋯ A confounding factor in the analysis is the susceptibility of the ICA decomposition for data changes yielding different DMN splitting between and after physiological correction conditions without comparable true change in the data. This issue is mitigated at higher ICA model orders. The results suggest that subject-level DMN can for some subjects be optimized by physiological correction, but on the group-level this contribution is minor.
-
J. Neurosci. Methods · Jan 2010
An MR-compatible device for automated and safe application of laser stimuli in experiments employing nociceptive stimulation.
In this paper the establishment of an automatic laser application device that reproducibly delivers laser stimuli in a safe, controlled, and reliable manner is presented. Nociceptive stimulation is widely used in functional magnetic resonance imaging (fMRI) experiments and a number of different methods are employed. One major advantage of laser stimulation as a method to administer painful stimuli is that it selectively activates nociceptors. ⋯ Additionally, MR-compatibility and functionality of the device were evaluated and assessed in a 3T MR scanner. Finally, the reliability and validity of the device were tested and demonstrated. It permits easy and investigator-independent use of laser stimulation in the MR scanner.
-
J. Neurosci. Methods · Jan 2010
Comparative StudyNeural electrode degradation from continuous electrical stimulation: comparison of sputtered and activated iridium oxide.
The performance of neural electrodes in physiological fluid, especially in chronic use, is critical for the success of functional electrical stimulation devices. Tips of the Utah electrode arrays (UEAs) were coated with sputtered iridium oxide film (SIROF) and activated iridium oxide film (AIROF) to study the degradation during charge injection consistent with functional electrical stimulation (FES). The arrays were subjected to continuous biphasic, cathodal first, charge balanced (with equal cathodal and anodal pulse widths) current pulses for 7h (>1 million pulses) at a frequency of 50 Hz. ⋯ The damage threshold for SIROF coated electrode tips of the UEA was between 60 nC with a charge density of 1.9 mC/cm(2) per phase and 80 nC with a charge density of 1.0 mC/cm(2) per phase. While for AIROF coated electrode tips, the threshold was between 40 nC with a charge density of 0.9 mC/cm(2) per phase and 50 nC with a charge density of 0.5 mC/cm(2) per phase. Compared to AIROF, SIROF showed higher damage threshold and therefore is highly recommended to be used as a stimulation material.