Biology subjects

Magnotta, V.

Publications and source records attributed to Magnotta, V..

3 recordsLinked to original sources

bioRxiv2026

Evaluations of retrospective frequency and phase correction methods for single-voxel MR spectroscopy at 7T

Subject motion and gradient heating-induced frequency and phase offsets result in spectral misalignment during single-voxel MR spectroscopy (SVS) acquisitions. Several methods have been presented to align the spectra, but their performance on a 7T system is unclear. This study aimed to evaluate the practical importance of four retrospective correction methods, namely creatine fitting, residual water, spectral registration, and cross-correlation. SVS data were collected from 127 participants (88/39 female/male, 39{+/-}15 years) using a semi-localization by adiabatic selective refocusing sequence at 7T. Changes in the spectral linewidth, signal-to-noise ratio (SNR), similarity (mean similarity matrix (SImean)), and metabolite quantification (concentration, relative Cramer-Rao lower bounds (rCRLB)) after correction were evaluated. A Wilcoxon signed rank test was used to evaluate these changes. The p-values were adjusted using the false discovery rate (q<0.05) for multiple comparisons. For significant changes, the effect size was further calculated using the Rosenthal formula. The results demonstrated that all correction methods resulted in a significant decrease in the spectral linewidth and significant increases in the spectral SNR and SImean. The mean changes by using the four methods were 0.76-0.99 Hz for the spectral linewidth change (effect sizes:0.73-0.86), 5.79-6.95 for the SNR change (effect size:0.60-0.72), and 0.03-0.03 for the SImean change (effect size:0.87-0.87). The correction also significantly increased the estimates of the metabolite concentrations of PCr, Gln, Glu, GPC, Ins, NAA, Scyllo, and Tau (effect size:0.25-0.57), and significantly decreased the rCRLBs (effect size:0.26-0.42) of Scyllo, Tau, and Gly. These results indicate that each method provides practical benefits in improving the spectral linewidth, SNR, and similarity by showing a strong to very strong effect of the improvements (effect size>0.60). The correction only showed a weak to moderate effect of the changes in the metabolite quantification (effect size<0.60), suggesting that whether the correction results in more reliable metabolite quantification requires further validation.

bioengineering↗

bioRxiv2023

Global functional connectivity of cognitive control network predicts task-switching performance in older adults

Executive Function (EF) is a complex higher order cognitive process that involves integrating subprocesses of attention, working memory, inhibition, and task switching and known to be one of the first cognitive functions to be affected by age related declines. Global Functional Connectivity (GFC), a measure of whole brain connectivity in brain networks such as the Cognitive Control Network (CCN), has been shown to measure the maintained EF abilities in older adults with cognitive impairment. However, this relationship has not been explored in a sample comprised of mostly cognitively normal older adults nor with the use of an experimental EF task sensitive to sub-processes most sensitive to aging. Task-switch paradigm studies have shown age-related deficits in holding and responding to rule sets while inhibiting another rule set in working memory (i.e., mixing cost). The present study aims to elucidate the relationship seen in EF performance using GFC and leveraging a task-switch paradigm that manipulates response overlap to increase cognitive demands on switching between tasks (e.g., mixing cost). Results show that greater negative DMN GFC coincides with older adults lower mixing costs, not CCN GFC. Findings indicate that DMN GFC, not CCN, may be important for EF performance in older adults.

neuroscience↗

bioRxiv2023

Functional Connectivity of the Cerebellar Vermis in Bipolar Disorder and Associations with Mood

PurposeStudies of the neural underpinnings of bipolar type I disorder have focused on the emotional control network. However, there is also growing evidence for cerebellar involvement, including abnormal structure, function, and metabolism. Here, we sought to assess functional connectivity of the cerebellum with the cerebrum in bipolar disorder and to assess whether any effects might depend on mood. MethodsThis cross-sectional study enrolled 128 participants with bipolar type I disorder and 83 control comparison participants who completed a 3T MRI scan, which included anatomical imaging as well as resting state BOLD imaging. Functional connectivity of the cerebellar vermis to all other brain regions was assessed. Based on quality control metrics of the fMRI data, 109 participants with bipolar disorder and 79 controls were used to in the statistical analysis comparing connectivity of the vermis as well as associations with mood. Potential impacts of medications were also explored. ResultsFunctional connectivity of the cerebellar vermis in bipolar disorder was found to differ significantly between brain regions known to be involved in the control of emotion, motor function, and language. While connections with emotion and motor control areas were significantly stronger in bipolar disorder, connection to a region associated language production was significantly weaker. In the participants with bipolar disorder, ratings of depression and mania were inversely associated with vermis functional connectivity. No effect of medications on these connections were observed. ConclusionTogether the findings suggest cerebellum may play a compensatory role in bipolar disorder and when it can no longer fulfill this role, depression and mania develop. The proximity of the cerebellar vermis to the skull may make this region a potential target for treatment with transcranial magnetic stimulation.

neuroscience↗