Differentiation of claustrum resting-state functional connectivity in healthy aging, Alzheimer's disease, and Parkinson's disease

The claustrum is a sheet-like of telencephalic gray matter structure whose function is poorly understood. The claustrum is considered a multimodal computing network due to its reciprocal connections with almost all cortical areas as well as subcortical structures. Although the claustrum has been involved in several neurodegenerative diseases, specific changes in connections of the claustrum remain unclear in Alzheimer's disease (AD), and Parkinson's disease (PD). Resting-state fMRI and T1-weighted structural 3D images from healthy elderly (n = 15), AD (n = 16), and PD (n = 12) subjects were analyzed. Seed-based FC analysis was performed using CONN FC toolbox and T1-weighted images were analyzed with the Computational Anatomy Toolbox for voxel-based morphometry analysis. While we observed a decreased FC between the left claustrum and sensorimotor cortex, auditory association cortex, and cortical regions associated with social cognition in PD compared with the healthy control group (HC), no significant difference was found in alterations in the FC of both claustrum comparing the HC and AD groups. In the AD group, high FC of claustrum with regions of sensorimotor cortex and cortical regions related to cognitive control, including cingulate gyrus, supramarginal gyrus, and insular cortex were demonstrated. In addition, the structural results show significantly decreased volume in bilateral claustrum in AD and PD compared with HC. There were no significant differences in the claustrum volumes between PD and AD groups so the FC may offer more precise findings in distinguishing changes for claustrum in AD and PD

Functional connectivity in neurodegenerative diseases: fMRI findings

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The effects of repetitive transcranial magnetic stimulation and aerobic exercise on cognition, balance and functional brain networks in patients with Alzheimer's disease

The purpose of this study was to investigate the effects of high-frequency repetitive Transcranial Magnetic Stimulation (rTMS) and aerobic exercises (AE) in addition to the pharmacological therapy (PT) in Alzheimer's Disease (AD). Twenty-seven patients with AD aged >= 60 years were included in the study and divided into 3 groups (rTMS, AE and control). All groups received PT. rTMS group (n = 10) received 20 Hz rTMS over dorsolateral prefrontal cortex (dlPFC) bilaterally and AE group (n = 9) received the structured moderate-intensity AE for 5 consecutive days/week over 2 weeks. Control group (n = 8) only received PT. Cognition, balance, mobility, quality of life (QoL), and resting state functional brain activity were evaluated one week before and one week after the interventions. (ClinicalTrials.gov ID:NCT05102045). Significant improvements were found in executive functions, behavior, and QoL in the rTMS group, in balance and mobility in the AE group, and in the visual memory and behavior in the control group (p < 0.05). Significant differences were found in the behavior in favor of the rTMS group, and balance in favor of the AE group (p < 0.05). There was a significant increase in activation on middle temporal gyrus, intra calcarine, central opercular cortex, superior parietal lobule, and paracingulate cortex in Default Mode Network (DMN) in the rTMS group (p < 0.05). High-frequency rTMS over bilateral dlPFC may improve executive functions and behavior and lead to increased activation in DMN, structured moderate-intensity AE may improve balance and mobility, and PT may improve memory and behaviour compared to pretreatment in AD

Neuronavigated rTMS inhibition of right pars triangularis anterior in stuttering: Differential effects on reading and speaking

Functional neuroimaging studies show an overactivation of speech and language related homologous areas of the right hemisphere in persons who stutter. In this study, we inhibited Broca's homologues using 1 Hz repetitive transcranial magnetic stimulation (rTMS) and assessed its effects on stuttering severity. The investigated cortical areas included pars opercularis (BA44), anterior and posterior pars triangularis (BA45), mouth area on the primary motor cortex (BA4). We collected reading and speaking samples before and after rTMS sessions and calculated the percentage of syllables stuttered. Only right anterior pars triangularis stimulation induced significant changes in speech fluency. Notably, the effects were differential for reading and speaking conditions. Overall, our results provide supportive evidence that right anterior BA45 may be a critical region for stuttering. The observed differential effects following the inhibition of right anterior BA45 merits further study of contributions of this region on different language domains in persons who stutter.Istanbul Universit

Effect of upper limb focal muscle vibration on cortical activity: A systematic review with a focus on primary motor cortex

This systematic review aimed to investigate the effects of upper extremity focal muscle vibration (FMV) on cortical activity. A systematic literature search was conducted for articles published in English in the SCOPUS, PEDro, PUBMED, REHABDATA, MEDLINE, and Web of Science databases. Eighteen studies (6 controlled and 12 experimental studies) were included in the systematic review. A total of 264 individuals (20 to 68 years) participated in the studies. The outcome of this review showed that FMV might have contradictory effects on cortical areas: (a) Reduction of cortical activity in the primary motor cortex (M1) and somatosensory cortex (S1), (b) no changes in the cortical activity of M1, and (c) increased cortical activity of M1 and S1. These effects may depend on different factors such as frequency and amplitude of FMV, vibration exposure time, and muscle status. However, no single factor can definitely be accounted for the variance

Resting-state fMRI analysis in apathetic Alzheimer's disease

PURPOSEDiagnosis of comorbid psychiatric conditions are a significant determinant for the prognosis of neurodegenerative diseases. Apathy, which is a behavioral executive dysfunction, frequently accompanies Alzheimer's disease (AD) and leads to higher daily functional loss. We assume that frontal lobe hypofunction in apathetic AD patients are more apparent than the AD patients without apathy. This study aims to address the neuroanatomical correlates of apathy in the early stage of AD using task-free functional magnetic resonance imaging (MRI).METHODSPatients (n=20) were recruited from the Neurology and Psychiatry Departments of Istanbul University, Istanbul School of Medicine whose first referrals were 6- to 12-month history of progressive cognitive decline. Patients with clinical dementia rating 0.5 and 1 were included in the study. The patient group was divided into two subgroups as apathetic and non-apathetic AD according to their psychiatric examination and assessment scores. A healthy control group was also included (n=10). All subjects underwent structural and functional MRI. The resting-state condition was recorded eyes open for 5 minutes.RESULTSThe difference between the three groups came up in the pregenual anterior cingulate cortex (pgACC) at the trend level (P = 0.056). Apathetic AD group showed the most constricted activation area at pgACC.CONCLUSIONThe region in and around anterior default mode network (pgACC) seems to mediate motivation to initiate behavior, and this function appears to weaken as the apathy becomes more severe in AD.Istanbul Universit

Enhancement of motor skill acquisition by intermittent theta burst stimulation: A pilot study

Objective This study aims to analyze the effects of intermittent theta burst stimulation (iTBS) on motor skill acquisition of healthy subjects when applied on alternate days to ensure high adherence to treatment. Materials and methods Ten healthy participants (40-54 years) were included in the study. The control group (CG) (60% female) only received motor training (i.e., finger tapping task-FTTa), whereas the experimental group (EG) (100% female) received iTBS in addition to the motor training (every other day for 5 sessions). Cortical excitability measurements were taken with TMS. The correct sequences of the finger tapping test (FTTe) were recorded for behavioral analysis. Results While SICI was increased by 0.03 in EG, ICF was increased by 0.18 between pre-and post-treatment. On the other hand, CG had a lower ICF difference (MD: 0.05) and a higher SICI difference (MD: 0.21). There was no difference between EG and CG in FTTe at the end of the intervention (p > 0.05 for all variables), except for the increased number of correct sequences within the EG (p = 0.018). There was a significant difference in FTTa between EG and CG, in favor of EG (p = 0.042). The effect size was 0.62. Conclusion Although no difference was found in terms of cortical excitability and FTTe between the EG and CG at the end of the alternate-day treatment, it seemed like iTBS increased cortical facilitation further than CG. Furthermore, the number of correct sequences in FTTe and FTTa was significantly increased in EG, showing that intermittent iTBS might improve motor learning and performance