Journal of neuroscience methods
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Epilepsy is a malfunction of the brain that affects over 50 million people worldwide. Epileptic seizures are usually characterized by an abnormal synchronized firing of neurons involved in the epileptic process. ⋯ There is now growing evidence that an improved understanding of the epileptic process can be achieved through the analysis of properties of epileptic brain networks and through the analysis of interactions in such networks. In this overview, we summarize recent methodological developments to assess synchronization phenomena in human epileptic brain networks and present findings obtained from analyses of brain electromagnetic signals recorded in epilepsy patients.
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J. Neurosci. Methods · Sep 2009
A fully implanted drug delivery system for peripheral nerve blocks in behaving animals.
Inhibiting peripheral nerve function can be useful for many studies of the nervous system or motor control. Accomplishing this in a temporary fashion in animal models by using peripheral nerve blocks permits studies of the immediate effects of the loss, and/or any resulting short-term changes and adaptations in behavior or motor control, while avoiding the complications commonly associated with permanent lesions, such as sores or self-mutilation. We have developed a method of quickly and repeatedly inducing temporary, controlled motor deficits in rhesus macaque monkeys via a chronically implanted drug delivery system. ⋯ Using this assembly for median and ulnar nerve blocks routinely resulted in over 80% losses in hand and wrist strength for rhesus monkeys. The assembly was also effective for inducing ambulatory motor deficits in rabbits through blocks of the sciatic nerve. Interestingly, while standard anesthetics were sufficient for the rabbit nerve blocks, the inclusion of epinephrine was essential for achieving significant motor blockade in the monkeys.
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J. Neurosci. Methods · Aug 2009
Gaussian mixture model-based segmentation of MR images taken from premature infant brains.
Segmentation of Magnetic Resonance multi-layer images of premature infant brain has additional challenges in comparison to normal adult brain segmentation. Images of premature infants contain lower signal to noise ratio due to shorter scanning times. Further, anatomic structure include still greater variations which can impair the accuracy of standard brain models. ⋯ The performance of the new method is compared voxel-by-voxel to the corresponding expert segmentation. The proposed method is found to produce more uniform results in comparison to three accustomary segmentation methods originally developed for adults. This is the case in particular when anatomic forms are still under development and differ in their form from those of adults.
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J. Neurosci. Methods · Jun 2009
Improving the recovery of S100B protein in cerebral microdialysis: implications for multimodal monitoring in neurocritical care.
Cerebral microdialysis is an established research tool that is used by an increasing number of neurocritical care units as a component of bedside multimodality monitoring. Body fluid biomarkers are an emerging tool for the assessment of brain injury. The correct interpretation of body fluid biomarker levels depends on the degree of recovery, i.e. relative recovery and the accuracy of the analytical technique. ⋯ Our data demonstrates that the 100 kDa MW cut-off catheter allows for the improved recovery of macromolecules in cerebral microdialysis research while maintaining the value of existing MD data for routine clinical use.
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J. Neurosci. Methods · Jun 2009
Modeling spinal cord contusion, dislocation, and distraction: characterization of vertebral clamps, injury severities, and node of Ranvier deformations.
Spinal cord contusion and transection models are widely used for studying spinal cord injury (SCI). Clinically, however, other biomechanical injury mechanisms such as vertebral dislocation and distraction frequently occur, but these injuries are difficult to produce in animals. We mechanically characterize a vertebral clamping strategy that enables the modeling of vertebral dislocation and distraction injuries--in addition to the standard contusion paradigm--in the rat cervical spine. ⋯ The greatest deformations in node of Ranvier geometry occurred at the dislocation epicenter. Given the importance of white matter damage in SCI pathology, the distinctiveness of these injury patterns demonstrate that the dislocation and distraction injury models complement existing contusion models. Together, these three animal models span a broader clinical spectrum for more reliably gauging the potential human efficacy of therapeutic strategies.