Task-related measures of short-interval intracortical inhibition and GABA levels in healthy young and older adults: A multimodal TMS-MRS study (original) (raw)
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Neurobiology of aging, 2018
Edited magnetic resonance spectroscopy (MRS) and transcranial magnetic stimulation (TMS) have often been used to study the integrity of the GABAergic neurotransmission system in healthy aging. To investigate whether the measurement outcomes obtained with these 2 techniques are associated with each other in older human adults, gamma-aminobutyric acid (GABA) levels in the left sensorimotor cortex were assessed with edited MRS in 28 older (63-74 years) and 28 young adults (19-34 years). TMS at rest was then used to measure intracortical inhibition (short-interval intracortical inhibition/long-interval intracortical inhibition), intracortical facilitation, interhemispheric inhibition from left to right primary motor cortex (M1) and recruitment curves of left and right M1. Our observations showed that short-interval intracortical inhibition and long-interval intracortical inhibition in the left M1 were reduced in older adults, while GABA levels did not significantly differ between age gr...
Journal of Neuroscience, 2013
Since GABA A -mediated intracortical inhibition has been shown to underlie plastic changes throughout the lifespan from development to aging, here, the aging motor system was used as a model to analyze the interdependence of plastic alterations within the inhibitory motorcortical network and level of behavioral performance. Double-pulse transcranial magnetic stimulation (dpTMS) was used to examine inhibition by means of short-interval intracortical inhibition (SICI) of the contralateral primary motor cortex in a sample of 64 healthy right-handed human subjects covering a wide range of the adult lifespan (age range 20 -88 years, mean 47.6 Ϯ 20.7, 34 female). SICI was evaluated during resting state and in an event-related condition during movement preparation in a visually triggered simple reaction time task. In a subgroup , manual motor performance was tested with tasks of graded dexterous demand.
Neuroscience & Biobehavioral Reviews, 2014
Please cite this article as: Levin, O., Fujiyama, H., Boisgontier, M.P., Swinnen, S.P., Summers, J.J.,Aging and motor inhibition: a converging perspective provided by brain stimulation and imaging approaches, Neuroscience and Biobehavioral Reviews (2014), http://dx.
NeuroImage, 2019
Response inhibition, the ability to withhold a dominant and prepotent response following a change in circumstance or sensory stimuli, declines with advancing age. While non-invasive brain stimulation (NiBS) has shown promise in alleviating some cognitive and motor functions in healthy older individuals, NiBS research focusing on response inhibition has mostly been conducted on younger adults. These extant studies have primarily focused on modulating the activity of distinct neural regions known to be critical for response inhibition, including the right inferior frontal gyrus (rIFG) and the pre-supplementary motor area (pre-SMA). However, given that changes in structural and functional connectivity have been associated with healthy aging, this review proposes that NiBS protocols aimed at modulating the functional connectivity between the rIFG and pre-SMA may be the most efficacious approach to investigate-and perhaps even alleviate-age-related deficits in inhibitory control.
tDCS-Induced Modulation of GABA Levels and Resting-State Functional Connectivity in Older Adults
The Journal of neuroscience : the official journal of the Society for Neuroscience, 2017
Transcranial direct current stimulation (tDCS) modulates human behavior, neuronal patterns, and metabolite concentrations, with exciting potential for neurorehabilitation. However, the understanding of tDCS-induced alterations on the neuronal level is incomplete, and conclusions from young adults, in whom the majority of studies have been conducted, cannot be easily transferred to older populations. Here, we investigated tDCS-induced effects in older adults (N = 48; age range, 50-79 years) using magnetic resonance spectroscopy to quantify GABA levels as well as resting-state functional magnetic resonance imaging to assess sensorimotor network strength and interhemispheric connectivity. In a randomized, counterbalanced, crossover design, we applied anodal tDCS (atDCS), cathodal tDCS (ctDCS), and sham tDCS (stDCS) over the left sensorimotor region. We observed a significant reduction of GABA levels after atDCS compared with stDCS, reflecting the preserved neuromodulatory effect of atD...
Neuroscience Letters, 2002
Using single and paired-pulse transcranial magnetic stimulation we compared the cortical excitability in two different age groups of healthy subjects (mean^SD age: 28.5^5.2 vs. 56.1^4.9 years). Motor evoked potentials were recorded from right extensor and flexor carpi radialis muscles. The effect of paired-pulse stimulation was assessed by the ratio conditioned/unconditioned response area with interstimulus intervals of 3 and 13 ms to test for intracortical inhibition and facilitation, respectively. To test the influence of sensory input the experiments were conducted without and with vibration of the extensor carpi radialis muscle. The intracortical inhibition was significantly greater in older subjects; however, during muscle vibration this difference between the two groups vanished. The different effect of vibration favors compensatory mechanisms to be responsible for a different paired-pulse excitability in middle-aged subjects. q
Age-Related Differences in Test-Retest Reliability in Resting-State Brain Functional Connectivity
PLoS ONE, 2012
Resting-state functional MRI (rs-fMRI) has emerged as a powerful tool for investigating brain functional connectivity (FC). Research in recent years has focused on assessing the reliability of FC across younger subjects within and between scansessions. Test-retest reliability in resting-state functional connectivity (RSFC) has not yet been examined in older adults. In this study, we investigated age-related differences in reliability and stability of RSFC across scans. In addition, we examined how global signal regression (GSR) affects RSFC reliability and stability. Three separate resting-state scans from 29 younger adults (18-35 yrs) and 26 older adults (55-85 yrs) were obtained from the International Consortium for Brain Mapping (ICBM) dataset made publically available as part of the 1000 Functional Connectomes project www.nitrc.org/projects/ fcon_1000. 92 regions of interest (ROIs) with 5 cubic mm radius, derived from the default, cingulo-opercular, fronto-parietal and sensorimotor networks, were previously defined based on a recent study. Mean time series were extracted from each of the 92 ROIs from each scan and three matrices of z-transformed correlation coefficients were created for each subject, which were then used for evaluation of multi-scan reliability and stability. The young group showed higher reliability of RSFC than the old group with GSR (p-value = 0.028) and without GSR (p-value ,0.001). Both groups showed a high degree of multiscan stability of RSFC and no significant differences were found between groups. By comparing the test-retest reliability of RSFC with and without GSR across scans, we found significantly higher proportion of reliable connections in both groups without GSR, but decreased stability. Our results suggest that aging is associated with reduced reliability of RSFC which itself is highly stable within-subject across scans for both groups, and that GSR reduces the overall reliability but increases the stability in both age groups and could potentially alter group differences of RSFC.
Age-related changes in intracortical inhibition are mental-cognitive state-dependent
Biological Psychology, 2014
Introduction: This study aimed to assess the impact of aging and 'state-dependency' on cortical excitability. Two studies investigated these factors using a motor task and found that the age-related differences observed at rest disappeared in the task condition. However, as both their tasks and excitability measurements involved the motor cortex, their results could be specific only to the motor system. To overcome this problem, the present study used a cognitive task to control mental state. Method: Intracortical inhibition/facilitation (ICI/ICF) were assessed in young and older adults at rest and during the cognitive task. The cortical silent period (CSP) was also evaluated. Results: ICI and CSP were reduced with aging. However, ICI differences between young and old people disappeared when they performed the cognitive task. Conclusion: Age and mental state modify cortical excitability. Taking these factors into consideration is crucial to clinical research using cortical excitability as a possible biomarker of pathology.
GABA Levels in Left and Right Sensorimotor Cortex Correlate across Individuals
Biomedicines, 2018
Differences in γ-aminobutyric acid (GABA) levels measured with Magnetic Resonance Spectroscopy have been shown to correlate with behavioral performance over a number of tasks and cortical regions. These correlations appear to be regionally and functionally specific. In this study, we test the hypothesis that GABA levels will be correlated within individuals for functionally related regions-the left and right sensorimotor cortex. In addition, we investigate whether this is driven by bulk tissue composition. GABA measurements using edited MRS data were acquired from the left and right sensorimotor cortex in 24 participants. T1-weighted MR images were also acquired and segmented to determine the tissue composition of the voxel. GABA level is shown to correlate significantly between the left and right regions ( = 0.64, < 0.03). Tissue composition is highly correlated between sides, but does not explain significant variance in the bilateral correlation. In conclusion, individual diffe...