scholarly journals Immediate impact of transcranial magnetic stimulation on brain structure: short-term neuroplasticity following one session of cTBS

2020 ◽  
Author(s):  
JeYoung Jung ◽  
Matthew A. Lambon Ralph
Keyword(s):  
Functional Connectivity ◽  
Functional Imaging ◽  
Semantic Processing ◽  
Cortical Plasticity ◽  
Cortical Excitability ◽  
Control Site ◽  
Adult Brain ◽  
Synaptic Activity ◽  
Structural Level ◽  
Functional Changes

AbstractRecent evidence demonstrates that activation-dependent neuroplasticity on a structural level can occur in a short time (2 hour or less) in humans. However, the exact time scale of structural plasticity in adult human brain remains unclear. Using voxel-based morphometry (VBM), we investigated changes in gray matter (GM) after one session of continuous theta-burst stimulation (cTBS) delivered to the anterior temporal lobe (ATL). Twenty-five participants were received cTBS over the left ATL or occipital pole as a control site outside of the scanner and had structural and functional imaging. During functional imaging, participants performed a semantic association task. VBM result revealed decreased GM in the left ATL and right cerebellum after ATL stimulation compared to the control stimulation. In addition, cTBS over the left ATL induced slower reaction time in sematic task performance, reduced regional activity at the target site, and altered functional connectivity between the left and right ATL during semantic processing. Furthermore, the ATL GM changes were associated with the functional connectivity changes in the ATL-connectivity during semantic processing. These structural alterations are mirrored by functional changes in cortical excitability attributed to the GM changes and demonstrate the rapid dynamics of cortical plasticity. Our findings support fast adjusting neuronal systems, such as postsynaptic morphology changes and neuronal turnover. Our results suggest that TBS is able to produce powerful changes in regional synaptic activity in human adult brain.

scholarly journals Cerebellar transcranial direct current stimulation reconfigurates static and dynamic functional connectivity of the resting-state networks

2020 ◽  
Author(s):  
Fatma Grami ◽  
Giovanni de Marco ◽  
Florian Bodranghien ◽  
Mario Manto ◽  
C. Habas
Keyword(s):  
Functional Connectivity ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Resting State ◽  
Cortical Excitability ◽  
Region Of Interest ◽  
Temporal Variations ◽  
Functional Changes ◽  
Direct Current Stimulation ◽  
The Right

Abstract Background Transcranial direct current stimulation (tDCS) of the cerebellum dynamically modulates cerebello-thalamo-cortical excitability in a polarity-specific manner during motor, visuo- motor and cognitive tasks. It remains to be established whether tDCS of the cerebellum impact also on resting-state intrinsically connected networks (ICNs). Such impact would open novel research and therapeutical doors for the neuromodulation of ICNs in human. Method: We combined tDCS applied over the right cerebellum and fMRI to investigate tDCS- induced resting-state intrinsic functional reconfiguration, using a randomized, sham-controlled design. fMRI data were recorded both before and after real anodal stimulation (2 mA, 20 min) or sham tDCS in 12 right-handed healthy volunteers. We resorted to a region-of-interest static correlational analysis and to a sliding window analysis to assess temporal variations in resting state FC between the cerebellar lobule VII and nodes of the main ICNs. Results After real tDCS and compared with sham tDCS, functional changes were observed between the cerebellum and ICNs. Static FC showed enhanced or decreased correlation between cerebellum and brain areas belonging to visual, default-mode (DMN), sensorimotor and salience networks (SN) (p-corrected < 0.05). The temporal variability (TV) of BOLD signal was significantly modified after tDCS displaying in particular a lesser TV between the whole lobule VII and DMN and central executive network and a greater TV between crus 2 and SN. Static and dynamic FC was also modified between cerebellar lobuli. Conclusion These results demonstrate short- and long-range static and majorly dynamic effects of tDCS stimulation of the cerebellum affecting distinct resting-state ICNs, as well as intracerebellar functional connectivity, so that tDCS of the cerebellum appears as a non-invasive tool reconfigurating the dynamics of ICNs.

scholarly journals Cerebellar transcranial direct current stimulation reconfigurates static and dynamic functional connectivity of the resting-state networks

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
F. Grami ◽  
G. de Marco ◽  
F. Bodranghien ◽  
M. Manto ◽  
C. Habas
Keyword(s):  
Functional Connectivity ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Resting State ◽  
Cortical Excitability ◽  
Region Of Interest ◽  
Temporal Variations ◽  
Functional Changes ◽  
Direct Current Stimulation ◽  
The Right

Abstract Background Transcranial direct current stimulation (tDCS) of the cerebellum dynamically modulates cerebello-thalamo-cortical excitability in a polarity-specific manner during motor, visuo- motor and cognitive tasks. It remains to be established whether tDCS of the cerebellum impact also on resting-state intrinsically connected networks (ICNs). Such impact would open novel research and therapeutical doors for the neuromodulation of ICNs in human. Method We combined tDCS applied over the right cerebellum and fMRI to investigate tDCS- induced resting-state intrinsic functional reconfiguration, using a randomized, sham-controlled design. fMRI data were recorded both before and after real anodal stimulation (2 mA, 20 min) or sham tDCS in 12 right-handed healthy volunteers. We resorted to a region-of-interest static correlational analysis and to a sliding window analysis to assess temporal variations in resting state FC between the cerebellar lobule VII and nodes of the main ICNs. Results After real tDCS and compared with sham tDCS, functional changes were observed between the cerebellum and ICNs. Static FC showed enhanced or decreased correlation between cerebellum and brain areas belonging to visual, default-mode (DMN), sensorimotor and salience networks (SN) (p-corrected < 0.05). The temporal variability (TV) of BOLD signal was significantly modified after tDCS displaying in particular a lesser TV between the whole lobule VII and DMN and central executive network and a greater TV between crus 2 and SN. Static and dynamic FC was also modified between cerebellar lobuli. Conclusion These results demonstrate short- and long-range static and majorly dynamic effects of tDCS stimulation of the cerebellum affecting distinct resting-state ICNs, as well as intracerebellar functional connectivity, so that tDCS of the cerebellum appears as a non-invasive tool reconfigurating the dynamics of ICNs.

Abstract W MP41: Potentiation of Gaba-Mediated Synaptic Inhibition in the Recovery Phase: A Novel Therapeutic Target for Stroke

Stroke ◽  
2014 ◽  
Vol 45 (suppl_1) ◽  
Author(s):  
Takeshi Hiu ◽  
Tonya Bliss ◽  
Jeanne Paz ◽  
Eric Wang ◽  
Zoya Farzampour ◽  
...  
Keyword(s):  
Pyramidal Cells ◽  
Recovery Phase ◽  
Synaptic Activity ◽  
Stroke Recovery ◽  
Functional Changes ◽  
Post Stroke ◽  
Array Tomography ◽  
Neuronal Inhibition ◽  
Gaba Signaling ◽  
Novel Therapeutic

Background: Stroke is a major cause of disability yet pharmacotherapy targeting the recovery phase is lacking. Cortical circuit reorganization adjacent to the stroke site promotes recovery, thus elucidating mechanisms that promote this plasticity could lead to new therapeutics. Tonic neuronal inhibition, mediated by extrasynaptic GABA A receptors,inhibits post-stroke recovery. However, effects of phasic (synaptic) GABA signaling - which promotes plasticity during development - are unknown. Here we use a combined approach of i) array tomography to determine the composition of GABA synapses in the post-stroke mouse brain, ii) electrophysiology to determine whether stroke leads to functional changes in GABA-mediated phasic inhibition, and (iii) treatment with zolpidem, an FDA-approved GABA agonist, to modulate recovery. Results: We found, using array tomography, a 1.7-fold increase in the number of GABAergic synapses containing the α1 receptor subunit in layer 5 of the peri-infarct cortex (synapse number/μm 3 : 0.039±0.006 (control) vs 0.064±0.006 (stroke); P<0.01), but not in layer 2/3. There was an associated increase in spontaneous inhibitory post-synaptic currents (sIPSC) specific to layer 5 pyramidal neurons (sIPSC charge (fC): -403±27.8 (control) vs -724±166 (stroke); p=0.03). This effect was transient, occurring during the onset of functional recovery. To test whether the increased phasic inhibitory GABAergic signaling promotes stroke recovery, we treated animals with zolpidem, an agonist with high affinity for α1 subunit-containing GABA A receptors. Low dose zolpidem increased GABA A phasic signaling in layer 5 pyramidal cells and notably increased the rate and extent of behavioral recovery without altering infarct size. Conclusions: These data provide the first evidence that enhanced GABA A -mediated synaptic activity during the recovery phase improves stroke outcome. These data identify modulation of phasic GABA signaling as a novel therapeutic strategy for stroke, indicate zolpidem as a potential drug to improve recovery, and underscore the necessity to distinguish the role of tonic and phasic GABA inhibition in stroke recovery.

Clinical correlates of hypothalamic functional changes in migraine patients

Cephalalgia ◽  
2021 ◽  
pp. 033310242110466
Author(s):  
Roberta Messina ◽  
Maria A Rocca ◽  
Paola Valsasina ◽  
Paolo Misci ◽  
Massimo Filippi
Keyword(s):  
Functional Connectivity ◽  
Resting State ◽  
Visual Processing ◽  
Episodic Migraine ◽  
Resting State Functional Connectivity ◽  
Functional Interaction ◽  
Functional Changes ◽  
Lingual Gyrus ◽  
Headache Impact

Objective To elucidate the hypothalamic involvement in episodic migraine and investigate the association between hypothalamic resting state functional connectivity changes and migraine patients’ clinical characteristics and disease progression over the years. Methods Ninety-one patients with episodic migraine and 73 controls underwent interictal resting state functional magnetic resonance imaging. Twenty-three patients and controls were re-examined after a median of 4.5 years. Hypothalamic resting state functional connectivity changes were investigated using a seed-based correlation approach. Results At baseline, a decreased functional interaction between the hypothalamus and the parahippocampus, cerebellum, temporal, lingual and orbitofrontal gyrus was found in migraine patients versus controls. Increased resting state functional connectivity between the hypothalamus and bilateral orbitofrontal gyrus was demonstrated in migraine patients at follow-up versus baseline. Migraine patients also experienced decreased right hypothalamic resting state functional connectivity with ipsilateral lingual gyrus. A higher migraine attack frequency was associated with decreased hypothalamic-lingual gyrus resting state functional connectivity at baseline, while greater headache impact at follow-up correlated with decreased hypothalamic-orbitofrontal gyrus resting state functional connectivity at baseline. At follow-up, a lower frequency of migraine attacks was associated with higher hypothalamic-orbitofrontal gyrus resting state functional connectivity. Conclusions During the interictal phase, the hypothalamus modulates the activity of pain and visual processing areas in episodic migraine patients. The hypothalamic-cortical interplay changes dynamically over time according to patients’ clinical features.

scholarly journals Retinal functional imager (RFI): Non-invasive functional imaging of the retina

2013 ◽  
Vol 5 (2) ◽  
pp. 250-257 ◽  
Author(s):  
Sunil Ganekal
Keyword(s):  
Functional Imaging ◽  
Structural Changes ◽  
Imaging System ◽  
Retinal Blood Flow ◽  
Capillary Perfusion ◽  
Functional Changes ◽  
Non Invasive ◽  
Retinal Disorders ◽  
Retinal Blood Flow Velocity ◽  
Perfusion Maps

Retinal functional imager (RFI) is a unique non-invasive functional imaging system with novel capabilities for visualizing the retina. The objective of this review was to show the utility of non-invasive functional imaging in various disorders. Electronic literature search was carried out using the websites www.pubmed.gov and www.google.com. The search words were retinal functional imager and non-invasive retinal imaging used in combination. The articles published or translated into English were studied. The RFI directly measures hemodynamic parameters such as retinal blood-flow velocity, oximetric state, metabolic responses to photic activation and generates capillary perfusion maps (CPM) that provides retinal vasculature detail similar to flourescein angiography. All of these parameters stand in a direct relationship to the function and therefore the health of the retina, and are known to be degraded in the course of retinal diseases. Detecting changes in retinal function aid early diagnosis and treatment as functional changes often precede structural changes in many retinal disorders. Nepal J Ophthalmol 2013; 5(10): 250-257 DOI: http://dx.doi.org/10.3126/nepjoph.v5i2.8738

scholarly journals Region-specific maladaptive gray matter myelination is associated with differential susceptibility to stress-induced behavior in male rodents and humans

2021 ◽  
Author(s):  
Kimberly L. P. Long ◽  
Linda L. Chao ◽  
Yurika Kazama ◽  
Anjile An ◽  
Kelsey Y. Hu ◽  
...  
Keyword(s):  
Gray Matter ◽  
Traumatic Stress ◽  
Adult Brain ◽  
Fear Learning ◽  
Male Rats ◽  
Adult Rats ◽  
Behavioral Variation ◽  
Weighted Estimates ◽  
Functional Changes ◽  
Symptom Profiles

AbstractBackgroundIndividual reactions to traumatic stress vary dramatically, yet the biological basis of this variation remains poorly understood. Recent studies have demonstrated surprising plasticity of oligodendrocytes and myelin in the adult brain, providing a potential mechanism by which aberrant structural and functional changes arise in the brain following trauma exposure.MethodsWe tested the hypothesis that gray matter myelin contributes to traumatic stress-induced behavioral variation. We exposed adult rats to a single, severe stressor and used a multimodal approach to characterize avoidance, startle, and fear-learning behavior. We quantified oligodendrocyte and myelin content in multiple brain areas and compared these measures to behavioral metrics. We then induced overexpression of the oligodendrogenic transcription factor Olig1 in the adult rat dentate gyrus (DG) to test the potential, causal role of oligodendrogenesis in behavioral variation. Lastly, T1-/T2-weighted estimates of myelin were compared to trauma-induced symptom profiles in humans.ResultsOligodendrocytes and myelin in the DG of the hippocampus positively correlated with stress-induced avoidance behaviors in male rats. In contrast, myelin levels in the amygdala positively correlated with contextual fear learning. Olig1 overexpression increased place avoidance compared to control virus animals, indicating that increased oligodendrocyte drive in the DG is sufficient to induce an avoidance behavioral phenotype. Finally, variation in myelin correlated with trauma-induced symptom profiles in humans in a region-specific manner that mirrored our rodent findings.ConclusionsThese results demonstrate a species-independent relationship between region-specific, gray matter oligodendrocytes and myelin and differential behavioral phenotypes following traumatic stress exposure. This study provides a novel biological framework for understanding the mechanisms that underlie individual variance in sensitivity to traumatic stress.

Neurochemical profiles of the anterior temporal lobe predict response of repetitive transcranial magnetic stimulation on semantic processing

2021 ◽  
Author(s):  
JeYoung Jung ◽  
Stephen Williams ◽  
Faezeh Sanae Nezhad ◽  
Matthew Lambon Ralph
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Temporal Lobe ◽  
Magnetic Stimulation ◽  
Semantic Processing ◽  
Cortical Excitability ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Semantic Representation ◽  
Cortical Region ◽  
Anterior Temporal Lobe ◽  
Neurochemical Profiles

Abstract The effect of repetitive transcranial magnetic stimulation can vary considerably across individuals, but the reasons for this still remain unclear. Here, we investigated whether the response to continuous theta-burst stimulation (cTBS) – an effective protocol for decreasing cortical excitability – related to individual differences in glutamate and GABA neurotransmission. We applied cTBS over the anterior temporal lobe (ATL), a hub for semantic representation, to explore the relationship between the baseline neurochemical profiles in this region and the response to this stimulation. Our experiments revealed that non-responders (subjects who did not show an inhibitory effect of cTBS on subsequent semantic performance) had higher excitatory-inhibitory balance (glutamate + glutamine/GABA ratio) in the ATL, which led to up-regulated task-induced regional activity as well as increased ATL-connectivity with other semantic regions compared to responders. These results disclose that the baseline neurochemical state of a cortical region can be a significant factor in predicting responses to cTBS.

scholarly journals An Effect of Chronic Stress on Prospective Memory via Alteration of Resting-State Hippocampal Subregion Functional Connectivity

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Jierong Chen ◽  
Zhen Wei ◽  
Hongying Han ◽  
Lili Jin ◽  
Chuanyong Xu ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Chronic Stress ◽  
Prospective Memory ◽  
Resting State ◽  
Functional Magnetic Resonance ◽  
Supramarginal Gyrus ◽  
Functional Changes ◽  
Cornu Ammonis ◽  
The Right ◽  
Left Middle

AbstractThe alteration of hippocampal function by chronic stress impairs higher order cognitive functions such as prospective memory (PM). However, how chronic stress affects hippocampal subregions related to PM remains largely unknown. In this study, the altered functional network of hippocampal subregions related to PM in chronic stress was explored. College students (N = 21) completed PM tasks and resting-state functional magnetic resonance imaging scans one month prior to (baseline) and during the final examination week (chronic stress). Hippocampal subregions’ seed-based functional connectivity (FC) and PM were compared between baseline and chronic stress. PM performance declined in chronic stress. The FC of the cornu ammonis 2, 3 and dentate gyrus (CA23DG) with the bilateral caudate and precuneus was increased in chronic stress, while the FC of the subicular complex (SUBC) with the left middle frontal gyrus, the left inferior parietal gyrus and the right supramarginal gyrus was decreased. There was a negative correlation between PM performance and the FC of hippocampal subregions. We found chronic stress impairs PM by decreasing the FC of SUBC and increasing the FC of CA23DG. These findings suggest functional changes in hippocampal subregion networks as a mechanism underlying the impairment of PM in chronic stress.

scholarly journals Geometry-dependent functional changes in iPSC-derived cardiomyocytes probed by functional imaging and RNA sequencing

PLoS ONE ◽  
2017 ◽  
Vol 12 (3) ◽  
pp. e0172671 ◽  
Author(s):  
Christopher A. Werley ◽  
Miao-Ping Chien ◽  
Jellert Gaublomme ◽  
Karthik Shekhar ◽  
Vincent Butty ◽  
...  
Keyword(s):  
Rna Sequencing ◽  
Functional Imaging ◽  
Functional Changes
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