scholarly journals Early-Stage Repetitive Transcranial Magnetic Stimulation Altered Posterior–Anterior Cerebrum Effective Connectivity in Methylazoxymethanol Acetate Rats

2021 ◽  
Vol 15 ◽  
Author(s):  
Huiling Guo ◽  
Yao Xiao ◽  
Dandan Sun ◽  
Jingyu Yang ◽  
Jie Wang ◽  
...  
Keyword(s):  
Nucleus Accumbens ◽  
Orbitofrontal Cortex ◽  
Resting State ◽  
Sham Group ◽  
Early Stage ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Effective Connectivity ◽  
Methylazoxymethanol Acetate ◽  
Fmri Study ◽  
Posterior Anterior

The aim of the current resting-state functional magnetic resonance imaging (fMRI) study was to investigate the potential mechanism of schizophrenia through the posterior–anterior cerebrum imbalance in methylazoxymethanol acetate (MAM) rats and to evaluate the effectiveness of repetitive transcranial magnetic stimulation (rTMS) as an early-stage intervention. The rats were divided into four groups: the MAM-sham group, vehicle-sham group, MAM-rTMS group, and vehicle-rTMS group. The rTMS treatment was targeted in the visual cortex (VC) in adolescent rats. Granger Causality Analysis (GCA) was used to evaluate the effective connectivity between regions of interest. Results demonstrated a critical right VC–nucleus accumbens (Acb)–orbitofrontal cortex (OFC) pathway in MAM rats; significant differences of effective connectivity (EC) were found between MAM-sham and vehicle-sham groups (from Acb shell to OFC: t = −2.553, p = 0.021), MAM-rTMS and MAM-sham groups (from VC to Acb core: t = −2.206, p = 0.043; from Acb core to OFC: t = 4.861, p < 0.001; from Acb shell to OFC: t = 4.025, p = 0.001), and MAM-rTMS and vehicle-rTMS groups (from VC to Acb core: t = −2.482, p = 0.025; from VC to Acb shell: t = −2.872, p = 0.012; from Acb core to OFC: t = 4.066, p = 0.001; from Acb shell to OFC: t = 3.458, p = 0.004) in the right hemisphere. Results of the early-stage rTMS intervention revealed that right nucleus accumbens played the role as a central hub, and VC was a potentially novel rTMS target region during adolescent schizophrenia. Moreover, the EC of right nucleus accumbens shell and orbitofrontal cortex was demonstrated to be a potential biomarker. To our knowledge, this was the first resting-state fMRI study using GCA to assess the deficits of a visual-reward neural pathway and the effectiveness of rTMS treatment in MAM rats. More randomized controlled trials in both animal models and schizophrenia patients are needed to further elucidate the disease characteristics.

Aberrant Functional and Effective Connectivity of the Frontostriatal Network in Unilateral Acute Tinnitus Patients with Hearing Loss

2021 ◽  
Author(s):  
Gang-Ping Zhou ◽  
Yu-Chen Chen ◽  
Wang-Wei Li ◽  
Heng-Le Wei ◽  
Yu-Sheng Yu ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Resting State ◽  
Large Scale ◽  
Early Stage ◽  
Effective Connectivity ◽  
Causality Analysis ◽  
Resting State Functional Connectivity ◽  
Midcingulate Cortex ◽  
Tinnitus Distress ◽  
Acute Tinnitus

Abstract Purpose: The present study combined resting-state functional connectivity (FC) and Granger causality analysis (GCA) to explore frontostriatal network dysfunction in unilateral acute tinnitus (AT) patients with hearing loss. Methods: The participants included 42 AT patients and 43 healthy control (HC) subjects who underwent resting-state functional magnetic resonance imaging (fMRI) scans. Based on the seed regions in the frontostriatal network, FC and GCA were conducted between the AT patients and HC subjects. Correlation analyses were used to examine correlations among altered FC values, GCA values, and clinical features in AT patients. Results: Compared with HCs, AT patients showed a general reduction in FC between the seed regions in the frontostriatal network and nonauditory areas, including the frontal cortices, midcingulate cortex (MCC) , supramarginal gyrus (SMG), and postcentral gyrus (PoCG) . Using the GCA algorithm, we detected abnormal effective connectivity (EC) in the inferior occipital gyrus (IOG), MCC, Cerebelum_Crus1, and PoCG. Furthermore, correlations between disrupted FC/EC and clinical characteristics, especially tinnitus distress-related characteristics, were found in AT patients. Conclusions: Our work demonstrated abnormal FC and EC between the frontostriatal network and several nonauditory regions in AT patients with hearing loss, suggesting that multiple large-scale network dysfunctions and interactions are involved in the perception of tinnitus. These findings not only enhance the current understanding of the frontostriatal network in tinnitus but also serve as a reminder of the importance of focusing on tinnitus at an early stage.

A resting-state fMRI study on early-stage drug-naïve Parkinson’s disease patients with drooling

2016 ◽  
Vol 634 ◽  
pp. 119-125 ◽  
Author(s):  
Yanbing Hou ◽  
Chunyan Luo ◽  
Jing Yang ◽  
Wei Song ◽  
Ruwei Ou ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Resting State ◽  
Early Stage ◽  
Resting State Fmri ◽  
Fmri Study ◽  
Drug Naïve

scholarly journals Effective connectivity extracts clinically relevant prognostic information from resting state activity in stroke

2020 ◽  
Author(s):  
Mohit H Adhikari ◽  
Joseph Griffis ◽  
Joshua S. Siegel ◽  
Michel Thiebaut de Schotten ◽  
Gustavo Deco ◽  
...  
Keyword(s):  
Resting State ◽  
Early Stage ◽  
Effective Connectivity ◽  
Individual Subject ◽  
Whole Brain ◽  
Long Term Outcome ◽  
Clinical Prognosis ◽  
State Activity ◽  
One Year ◽  
Time Point

ABSTRACTRecent resting-state fMRI studies in stroke patients have identified two robust biomarkers of acute brain dysfunction: a reduction of inter-hemispheric functional connectivity (FC) between homotopic regions of the same network, and an abnormal increase of ipsilesional FC between task-negative and task-positive resting-state networks (RSNs). Whole-brain computational modeling studies, at the individual subject level, using undirected effective connectivity (EC) derived from empirically measured FC, have shown a reduction of measures of integration and segregation in stroke as compared to healthy brains. Here we employ a novel method, first, to infer whole-brain directional EC from zero-lagged and lagged FC, then, to compare it to empirically measured FC for predicting stroke vs. healthy status, and patient performance (zero, one, multiple deficits) across neuropsychological tests. We also investigated the accuracy of FC vs. model EC in predicting the long-term outcome from acute measures.Both FC and EC predicted healthy from stroke individuals significantly better than the chance-level, however, EC accuracy was significantly higher than that of FC at 1-2 weeks, three months, and one year post-stroke. The predictive FC links mainly included those reported in previous studies (within-network inter-hemispheric, and between task-positive and -negative networks intra-hemispherically). Predictive EC links included additional between-network links. EC was a better predictor than FC of the number of behavioral domains in which patients suffered deficits, both at two weeks and one-year post onset of stroke. Interestingly, patient deficits at one-year time point were better predicted by EC values at two weeks rather than at one-year time point. Our results thus demonstrate that the second-order statistics of fMRI resting-state activity at an early stage of stroke, derived from a whole-brain EC, estimated in a model fitted to reproduce the propagation of BOLD activity, has pertinent information for clinical prognosis.

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