Delayed grip relaxation and altered modulation of intracortical inhibition with aging

AbstractInhibitory control is the ability to suppress inappropriate movements and unwanted actions, allowing to regulate impulses and responses. This ability can be measured via the Stop Signal Task, which provides a temporal index of response inhibition, namely the stop signal reaction time (SSRT). At the neural level, Transcranial Magnetic Stimulation (TMS) allows to investigate motor inhibition within the primary motor cortex (M1), such as the cortical silent period (CSP) which is an index of GABAB-mediated intracortical inhibition within M1. Although there is strong evidence that intracortical inhibition varies during action stopping, it is still not clear whether differences in the neurophysiological markers of intracortical inhibition contribute to behavioral differences in actual inhibitory capacities. Hence, here we explored the relationship between intracortical inhibition within M1 and behavioral response inhibition. GABABergic-mediated inhibition in M1 was determined by the duration of CSP, while behavioral inhibition was assessed by the SSRT. We found a significant positive correlation between CSP’s duration and SSRT, namely that individuals with greater levels of GABABergic-mediated inhibition seem to perform overall worse in inhibiting behavioral responses. These results support the assumption that individual differences in intracortical inhibition are mirrored by individual differences in action stopping abilities.

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Examining motor evoked potential amplitude and short‐interval intracortical inhibition on the up‐going and down‐going phases of a transcranial alternating current stimulation (tacs) imposed alpha oscillation

European Journal of Neuroscience ◽

10.1111/ejn.15124 ◽

2021 ◽

Author(s):

Ann‐Maree Vallence ◽

Kathryn Dansie ◽

Mitchell R. Goldsworthy ◽

Suzanne M. McAllister ◽

Ruiting Yang ◽

...

Keyword(s):

Evoked Potential ◽

Short Interval ◽

Motor Evoked Potential ◽

Intracortical Inhibition ◽

Alternating Current ◽

Potential Amplitude ◽

Alpha Oscillation ◽

Transcranial Alternating Current Stimulation

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Modulation of intracortical inhibition during physically performed and mentally simulated balance tasks

European Journal of Applied Physiology ◽

10.1007/s00421-020-04577-1 ◽

2021 ◽

Vol 121 (5) ◽

pp. 1379-1388

Author(s):

A. Mouthon ◽

J. Ruffieux ◽

W. Taube

Keyword(s):

Motor Evoked Potentials ◽

Action Observation ◽

Short Interval ◽

Intracortical Inhibition ◽

Mental Simulation ◽

Task Execution ◽

Postural Tasks ◽

Execution Condition ◽

The One ◽

Postural Task

Abstract Purpose Action observation (AO) during motor imagery (MI), so-called AO + MI, has been proposed as a new form of non-physical training, but the neural mechanisms involved remains largely unknown. Therefore, this study aimed to explore whether there were similarities in the modulation of short-interval intracortical inhibition (SICI) during execution and mental simulation of postural tasks, and if there was a difference in modulation of SICI between AO + MI and AO alone. Method 21 young adults (mean ± SD = 24 ± 6.3 years) were asked to either passively observe (AO) or imagine while observing (AO + MI) or physically perform a stable and an unstable standing task, while motor evoked potentials and SICI were assessed in the soleus muscle. Result SICI results showed a modulation by condition (F2,40 = 6.42, p = 0.009) with less SICI in the execution condition compared to the AO + MI (p = 0.009) and AO (p = 0.002) condition. Moreover, switching from the stable to the unstable stance condition reduced significantly SICI (F1,20 = 8.34, p = 0.009) during both, physically performed (− 38.5%; p = 0.03) and mentally simulated balance (− 10%, p < 0.001, AO + MI and AO taken together). Conclusion The data demonstrate that SICI is reduced when switching from a stable to a more unstable standing task during both real task execution and mental simulation. Therefore, our results strengthen and further support the existence of similarities between executed and mentally simulated actions by showing that not only corticospinal excitability is similarly modulated but also SICI. This proposes that the activity of the inhibitory cortical network during mental simulation of balance tasks resembles the one during physical postural task execution.

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Remote muscle priming anodal transcranial direct current stimulation attenuates short interval intracortical inhibition and increases time to task failure of a constant workload cycling exercise

Experimental Brain Research ◽

10.1007/s00221-021-06103-x ◽

2021 ◽

Author(s):

Simranjit K. Sidhu

Keyword(s):

Direct Current ◽

Transcranial Direct Current Stimulation ◽

Short Interval ◽

Intracortical Inhibition ◽

Cycling Exercise ◽

Task Failure ◽

Direct Current Stimulation

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The Functional Role of Response Suppression during an Urge to Relieve Pain

Journal of Cognitive Neuroscience ◽

10.1162/jocn_a_01423 ◽

2019 ◽

Vol 31 (9) ◽

pp. 1404-1421

Author(s):

Kelsey K. Sundby ◽

Johanna Wagner ◽

Adam R. Aron

Keyword(s):

Short Interval ◽

Intracortical Inhibition ◽

Gabaergic Interneuron ◽

Response Suppression ◽

Active Response ◽

Relieve Pain ◽

Clinical Disorders ◽

Functional Relevance ◽

Interneuron Activity

Being in the state of having both a strong impulse to act and a simultaneous need to withhold is commonly described as an “urge.” Although urges are part of everyday life and also important to several clinical disorders, the components of urge are poorly understood. It has been conjectured that withholding an action during urge involves active response suppression. We tested that idea by designing an urge paradigm that required participants to resist an impulse to press a button and gain relief from heat (one hand was poised to press while the other arm had heat stimulation). We first used paired-pulse TMS over motor cortex (M1) to measure corticospinal excitability of the hand that could press for relief, while participants withheld movement. We observed increased short-interval intracortical inhibition, an index of M1 GABAergic interneuron activity that was maintained across seconds and specific to the task-relevant finger. A second experiment replicated this. We next used EEG to better “image” putative cortical signatures of motor suppression and pain. We found increased sensorimotor beta contralateral to the task-relevant hand while participants withheld the movement during heat. We interpret this as further evidence of a motor suppressive process. Additionally, there was beta desynchronization contralateral to the arm with heat, which could reflect a pain signature. Strikingly, participants who “suppressed” more exhibited less of a putative “pain” response. We speculate that, during urge, a suppressive state may have functional relevance for both resisting a prohibited action and for mitigating discomfort.

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