Cheryl Richards edited Pathophysiology.md  about 8 years ago

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Transcriptome analysis of the human striatum in Tourette syndrome \citep{25199956} | This important study follows up on the autopsy results from the Vaccarino lab by comparing RNA transcripts from the basal ganglia of 9 TS and 9 matched control subjects. The most strongly associated set of downregulated transcripts involved striatal interneurons, consistent with the autopsy studies. The leading set of upregulated transcripts involved immune-related genes even though none of the TS subjects met the diagnostic criteria for pediatric autoimmune streptococcal-associated neuropsychiatric disorders or pediatric acute onset neuropsychiatric syndrome. There was a lack of overlap between the results obtained in the present study using brain tissue and previous studies using blood samples. The authors conclude that their results "strongly [implicate] disrupted interneuron signaling in the pathophysiology of severe TS and suggests that metabolic alterations may be linked to their death or dysfunction."  The GAGA-A antagonist picrotoxin was injected into targets throughout corticostriatal regions in adult mice \cite{25597650}. Infusions into the central and dorsolateral striatum produced intermittent non-rhythmic stereotyped lifting of the front or hind paw or head jerks. Infusions into the dorsomedial striatum did not have a significant behavioral effect. Infusion into the ventral striaum produced locomotor activation with sterotypical sniffing and wall licking. Infusions into the sensorimotor cortex produced similar movements in addition to exploration of the cage. sniffing and occasional licking.  ### Neuroimaging and electrophysiology studies  An important (though frustrating) recent finding was that even very small head movements can cause artifactual findings in structural MRI \citep{25498430} . Neroimaging scans were performed on 12 healthy adults while they were still or engaged in specific types of movements including nodding, headshaking and a movement that they invented and then repeated during the scan run. Even during scans when subjects remained still, there was an average of 3 mm/s RMSpm (RMS displacement per minute), but it was significantly higher during the motion conditions. In general there was a 1-3% local volume loss for each 1 mm/s RMSpm increase. The greatest thickness reductions were found in the pre- and post-central cortex, in the temporal lobes and pole, and enthorhinal and parahippocampal regions. Increased thickness associated with motion was seen in regions associated with deep sulci such as the medial orbital frontal and lateral frontal areas. Recommendations were made to reduce head motion during scans as much as possible and then control for motion in the statistical analysis, along with using correlational analyses to determine the associations between head motion and the predictors of interest. A more recent article \citep{26654788} described the development of a system for motion tracking and prospective motion correction, and mentions similar systems that are available for other scanner platforms. The challenges using neuroimaging techniques to study pediatric and clinical subjects are described in detail along with various strategies that can be used to collect high-quality data \cite{26754461} .