Are individual responses to theta-burst rTMS in cortical excitability related to changes in motor network connectivity?

AbstractTheta-burst stimulation (TBS) is a form of non-invasive neuromodulation which is delivered in an intermittent (iTBS) or continuous (cTBS) manner. Although 600 pulses is the most common dose, the goal of these experiments was to evaluate the effect of higher per-dose pulse numbers on cortical excitability. Sixty individuals were recruited for 2 experiments. In Experiment 1, participants received 600, 1200, 1800, or sham (600) iTBS (4 visits, counterbalanced, left motor cortex, 80% active threshold). In Experiment 2, participants received 600, 1200, 1800, 3600, or sham (600) cTBS (5 visits, counterbalanced). Motor evoked potentials (MEP) were measured in 10-min increments for 60 min. For iTBS, there was a significant interaction between dose and time (F = 3.8296, p = 0.01), driven by iTBS (1200) which decreased excitability for up to 50 min (t = 3.1267, p = 0.001). For cTBS, there was no overall interaction between dose and time (F = 1.1513, p = 0.33). Relative to sham, cTBS (3600) increased excitability for up to 60 min (t = 2.0880, p = 0.04). There were no other significant effects of dose relative to sham in either experiment. Secondary analyses revealed high within and between subject variability. These results suggest that iTBS (1200) and cTBS (3600) are, respectively, the most effective doses for decreasing and increasing cortical excitability.

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Ventral attention and motor network connectivity is relevant to functional impairment in spatial neglect after right brain stroke

Brain and Cognition ◽

10.1016/j.bandc.2018.11.013 ◽

2019 ◽

Vol 129 ◽

pp. 16-24 ◽

Cited By ~ 6

Author(s):

A.M. Barrett ◽

Olga Boukrina ◽

Soha Saleh

Keyword(s):

Functional Impairment ◽

Network Connectivity ◽

Spatial Neglect ◽

Right Brain ◽

Motor Network ◽

Brain Stroke

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Dose-Dependent Effects of Theta Burst rTMS on Cortical Excitability and Resting-State Connectivity of the Human Motor System

Journal of Neuroscience ◽

10.1523/jneurosci.4993-13.2014 ◽

2014 ◽

Vol 34 (20) ◽

pp. 6849-6859 ◽

Cited By ~ 91

Author(s):

C. Nettekoven ◽

L. J. Volz ◽

M. Kutscha ◽

E.-M. Pool ◽

A. K. Rehme ◽

...

Keyword(s):

Resting State ◽

Motor System ◽

Cortical Excitability ◽

Human Motor ◽

Resting State Connectivity ◽

Dose Dependent ◽

Theta Burst

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Effects of a single session of cathodal transcranial direct current stimulation primed intermittent theta-burst stimulation on heart rate variability and cortical excitability measures

Indian Journal of Physiology and Pharmacology ◽

10.25259/ijpp_339_2020 ◽

2021 ◽

Vol 65 ◽

pp. 162-166

Author(s):

B. N. Keerthy ◽

Sai Sreevalli Sarma Sreepada ◽

Shalini S. Naik ◽

Anushree Bose ◽

Raju Hanumegowda ◽

...

Keyword(s):

Healthy Volunteers ◽

Dorsolateral Prefrontal Cortex ◽

Cortical Excitability ◽

Single Session ◽

Theta Burst Stimulation ◽

Burst Stimulation ◽

Cathodal Tdcs ◽

Dorsolateral Prefrontal ◽

Before And After ◽

Theta Burst

Objectives: Transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) have been used as neuromodulators in neuropsychiatric conditions. This study is aimed to find the effects of a single session of priming cathodal tDCS with intermittent theta-burst stimulation (iTBS) over left dorsolateral prefrontal cortex on heart rate variability (HRV) and cortical excitability parameters before and after perturbation. Materials and Methods: The neuromodulatory techniques used in the study were Cathodal tDCS for 20 min followed by iTBS for 3 min on the left dorsolateral prefrontal cortex (DLPFC). HRV variables and TMS parameters were recorded before and after this intervention of combined neuromodulation in 31 healthy volunteers (20 males and 11 females; age range of 19–35 years with Mean ± SD = 24.2 ± 4.7 years). Results: The results showed an overall increase in cortical excitability and parasympathetic dominance in healthy volunteers. Other measures of cortical excitability and HRV did not change significantly following single session of combined neuromodulation. Conclusion: This study showed that there is an overall increase in cortical excitability and parasympathetic dominance in the cohort of healthy volunteers following a combination of neuromodulation involving cathodal tDCS followed by iTBS over left DLPFC. Future studies exploring the effects of other possible combinations with sham stimulation could be carried out to explore the utility of dual stimulation as add-on therapy in disorders.

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Local GABA concentration is related to network-level resting functional connectivity

eLife ◽

10.7554/elife.01465 ◽

2014 ◽

Vol 3 ◽

Cited By ~ 86

Author(s):

Charlotte J Stagg ◽

Velicia Bachtiar ◽

Ugwechi Amadi ◽

Christel A Gudberg ◽

Andrei S Ilie ◽

...

Keyword(s):

Functional Connectivity ◽

Resting State ◽

Primary Motor Cortex ◽

Empirical Studies ◽

Network Connectivity ◽

Resting State Fmri ◽

Resonance Spectroscopy ◽

Resting State Networks ◽

Inhibitory Neurotransmitter ◽

Motor Network

Anatomically plausible networks of functionally inter-connected regions have been reliably demonstrated at rest, although the neurochemical basis of these ‘resting state networks’ is not well understood. In this study, we combined magnetic resonance spectroscopy (MRS) and resting state fMRI and demonstrated an inverse relationship between levels of the inhibitory neurotransmitter GABA within the primary motor cortex (M1) and the strength of functional connectivity across the resting motor network. This relationship was both neurochemically and anatomically specific. We then went on to show that anodal transcranial direct current stimulation (tDCS), an intervention previously shown to decrease GABA levels within M1, increased resting motor network connectivity. We therefore suggest that network-level functional connectivity within the motor system is related to the degree of inhibition in M1, a major node within the motor network, a finding in line with converging evidence from both simulation and empirical studies.

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Dynamics of brain connectivity after stroke

Reviews in the Neurosciences ◽

10.1515/revneuro-2018-0082 ◽

2019 ◽

Vol 30 (6) ◽

pp. 605-623 ◽

Cited By ~ 5

Author(s):

Adela Desowska ◽

Duncan L. Turner

Keyword(s):

Brain Connectivity ◽

Effective Connectivity ◽

Network Connectivity ◽

Connectivity Pattern ◽

Compensatory Mechanisms ◽

Neural Structure ◽

Motor Network ◽

The Central Nervous System ◽

Dynamic Time ◽

The Impact

Abstract Recovery from a stroke is a dynamic time-dependent process, in which the central nervous system reorganises to accommodate for the impact of the injury. The purpose of this paper is to review recent longitudinal studies of changes in brain connectivity after stroke. A systematic review of research papers reporting functional or effective connectivity at two or more time points in stroke patients was conducted. Stroke leads to an early reduction of connectivity in the motor network. With recovery time, the connectivity increases and can reach the same levels as in healthy participants. The increase in connectivity is correlated with functional motor gains. A new, more randomised pattern of connectivity may then emerge in the longer term. In some instances, a pattern of increased connectivity even higher than in healthy controls can be observed, and is related either to a specific time point or to a specific neural structure. Rehabilitation interventions can help improve connectivity between specific regions. Moreover, motor network connectivity undergoes reorganisation during recovery from a stroke and can be related to behavioural recovery. A detailed analysis of changes in connectivity pattern may enable a better understanding of adaptation to a stroke and how compensatory mechanisms in the brain may be supported by rehabilitation.

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