Journal of neuroscience methods
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J. Neurosci. Methods · Sep 2015
The use of a cerebral perfusion and immersion-fixation process for subsequent white matter dissection.
The Klingler's method for white matter dissection revolutionized the study of deep cerebral anatomy. Although this technique made white matter dissection more feasible and widely used, it still presents some intrinsic limitations. ⋯ These results provide encouraging data about the possibility to use a perfusion fixation process, which may help in improving the quality of white matter dissection for research, didactic purposes and surgical training.
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To date, the blood oxygenated-level dependent (BOLD) functional magnetic resonance imaging (fMRI) technique has enabled an objective and deeper understanding of pain processing mechanisms embedded within the human central nervous system (CNS). In order to further comprehend the benefits and limitations of BOLD fMRI in the context of pain as well as the corresponding subjective pain ratings, we evaluated the univariate response, test-retest reliability and confidence intervals (CIs) at the 95% level of both data types collected during evoked stimulation of 40°C (non-noxious), 44°C (mildly noxious) and a subject-specific temperature eliciting a 7/10 pain rating. ⋯ Test-retest reliability was observed to be highest for VAS pain ratings obtained during the 7/10 pain stimulation (ICC=0.938), while ICC values of pain fMRI data for a distribution of CNS structures ranged from 0.5 to 0.859 (p<0.05). Importantly, the upper and lower confidence interval CI bounds reported herein could be utilized in subsequent trials involving healthy volunteers to hypothesize the magnitude of effect required to overcome inherent variability of either VAS pain ratings or BOLD responses evoked during innocuous or noxious thermal stimulation.
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Assessment of the nociceptive withdrawal reflex (NWR) is frequently applied to probe the excitability level of the spinal nociceptive circuitry. In humans, the NWR threshold (NWR-T) is often estimated by applying electrical stimulation over the sural nerve at the lateral malleolus. Such stimulation may be associated with substantial pain and discomfort rendering completion of the assessment infeasible. ⋯ These results support a paradigm shift within NWR-T estimation favoring stimulation at the arch of the foot.
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J. Neurosci. Methods · Jul 2015
Comparative StudyA novel method for delivering ramped cooling reveals rat behaviours at innocuous and noxious temperatures: A comparative study of human psychophysics and rat behaviour.
Thermal sensory testing in rodents informs human pain research. There are important differences in the methodology for delivering thermal stimuli to humans and rodents. This is particularly true in cold pain research. These differences confound extrapolation and de-value nociceptive tests in rodents. ⋯ Brief paw removal in the rat is driven by non-nociceptive afferents, as is the perception of cooling in humans. This is in contrast to the nociceptor-driven withdrawal from colder temperatures. These findings have important implications for the interpretation of data generated in older cold pain models and consequently our understanding of cold perception and pain.
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J. Neurosci. Methods · Jun 2015
Non-invasive mapping of bilateral motor speech areas using navigated transcranial magnetic stimulation and functional magnetic resonance imaging.
Navigated transcranial magnetic stimulation (nTMS) is a modern precise method to activate and study cortical functions noninvasively. We hypothesized that a combination of nTMS and functional magnetic resonance imaging (fMRI) could clarify the localization of functional areas involved with motor control and production of speech. ⋯ The reviewer-verified speech disruptions induced by nTMS provided clinically relevant information, and fMRI might explain further the function of the cortical area. nTMS and fMRI complement each other, and their combination should be advocated when assessing individual localization of speech network.