Journal of neuroscience methods
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J. Neurosci. Methods · Mar 2008
Validation of a fiducial-based atlas localization method for deep brain stimulation contacts in the area of the subthalamic nucleus.
Differences in the location of active contacts with respect to the subthalamic nucleus (STN) may account for much variability in motor, psychiatric and cognitive responses to deep brain stimulation (DBS) in Parkinson disease (PD) patients. Because localization of STN based on hypointensity in T2-weighted MR images is unreliable and further limited by artifacts from the metal electrodes, we developed and validated a method to transform brain images into stereotactic space [Mai JK, Assheuer J, Paxinos G. Atlas of the Human Brain, 2nd ed. ⋯ Mean discrepancies were 0.1, 0.9, and 0.0mm (x, y, z) with standard deviations of 0.9, 0.7 and 1.1mm, respectively. Because post-operative determination of contact location with respect to the STN is necessary due to possible shifting of electrodes during surgical placement, we identified active contacts on post-operative CT images and transformed their locations into stereotactic space. This method provides an accurate and reliable means for STN DBS contact localization.
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J. Neurosci. Methods · Feb 2008
Automated video-based facial expression analysis of neuropsychiatric disorders.
Deficits in emotional expression are prominent in several neuropsychiatric disorders, including schizophrenia. Available clinical facial expression evaluations provide subjective and qualitative measurements, which are based on static 2D images that do not capture the temporal dynamics and subtleties of expression changes. Therefore, there is a need for automated, objective and quantitative measurements of facial expressions captured using videos. ⋯ To analyze temporal facial expression changes, we employ probabilistic classifiers that analyze facial expressions in individual frames, and then propagate the probabilities throughout the video to capture the temporal characteristics of facial expressions. The applications of our method to healthy controls and case studies of patients with schizophrenia and Asperger's syndrome demonstrate the capability of the video-based expression analysis method in capturing subtleties of facial expression. Such results can pave the way for a video-based method for quantitative analysis of facial expressions in clinical research of disorders that cause affective deficits.
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J. Neurosci. Methods · Feb 2008
Inflammatory pain in the rabbit: a new, efficient method for measuring mechanical hyperalgesia in the hind paw.
The discovery of novel analgesic compounds that target some receptors can be challenging due to species differences in ligand pharmacology. If a putative analgesic compound has markedly lower affinity for rodent versus other mammalian orthologs of a receptor, the evaluation of antinociceptive efficacy in non-rodent species becomes necessary. Here, we describe a new, efficient method for measuring inflammation-associated nociception in conscious rabbits. ⋯ An established hyperalgesia was dose dependently reversed by morphine sulfate (ED50=0.096 mg/kg, s.c.) or the bradykinin B1 receptor peptide antagonist [des-Arg10, Leu9]-kallidin (ED50=0.45 mg/kg, s.c.). Rabbits treated with the novel B(1) receptor small molecule antagonist compound A also showed dose-dependent reversal of hyperalgesia (ED50=20.19 mg/kg, s.c.) and analysis of plasma samples taken from these rabbits showed that, unlike other rabbit pain models, the current method permits the evaluation of pharmacokinetic-pharmacodynamic (PK-PD) relationships (compound A plasma EC50=402.6 nM). We conclude that the Electrovonfrey method can be used in rabbits with inflammatory pain to generate reliable dose- and plasma concentration-effect curves for different classes of analgesics.
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J. Neurosci. Methods · Jan 2008
A novel automated method for measuring the effect of analgesics on formalin-evoked licking behavior in rats.
The behavioral assessment of pain is essential for the analysis of pain mechanisms and the evaluation of analgesic drugs. The formalin test is one of such methods widely used as a model of injury-induced pain in rodents. This test is manually demanding and the recording of results is left to the subjectivity of the experimenters. ⋯ In addition, frames in which moving velocity of these markers is less than 2.5mm/s was neglected for calculation in order to eliminate sedative effect on the recorded data. On these conditions, subcutaneous administration of morphine in rats dose-dependently decreased formalin-elicited nociceptive responses. These results suggest that under optimal conditions the automated technique when applied to pharmacological studies are more reliable and efficient than if they are manually recorded.
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J. Neurosci. Methods · Jan 2008
Lentiviral-mediated targeted transgene expression in dorsal spinal cord glia: tool for the study of glial cell implication in mechanisms underlying chronic pain development.
Activated glial cells in the dorsal spinal cord take an important part in the development of pain after peripheral nerve injury. Our understanding of mechanisms involved in functional changes of spinal glia remains incomplete. Excepting drugs that completely disrupt glial function, pharmacological studies fail to target glia and to modify locally its function in order to really discriminate the role of neuronal versus glial cells in chronic pain. ⋯ EGFP transgene was mainly expressed in astrocytes and microglial cells whereas less than 9% of cells containing EGFP were neurons. Notably, LV-EGFP administration and EGFP overexpression in glial cells did neither modify glial activity, nor alter animal's nociceptive or locomotor behaviors. Targeted modulation of the expression of gene of interest in glial cells, closely restricted to a particular region of the spinal cord, may thus represent an interesting approach to refine the understanding of mechanisms by which spinal glial cells participate in pain processing.