Age-related changes in TMS-based gamma-aminobutyric acid (GABA) modulation during a unimanual simple and choice reaction time task.
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1
Movement Control and Neuroplasticity Research Group, Department of Kinesiology, Biomedical Sciences Group, KU Leuven, Belgium
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2
REVAL Rehabilitation Research Center, Belgium
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3
Leuven Research Institute for Neuroscience & Disease (LIND), Belgium
Objectives: We explored age-related changes in gamma-aminobutyric acid (GABA) modulation in the dominant primary motor cortex (M1) during a simple (SRT) and choice reaction time task (CRT) assessed by transcranial magnetic stimulation (TMS) based short-interval intracortical inhibition (SICI).
Methods: 15 healthy older (65-80 years, 70.73±4.11 (mean ± SD); 7 male; R-handed: lateralization quotient: 95.58±7.87 (mean ± SD)) and 15 young adults (aged 20-28 years, 23.40±2.20 (mean ± SD); 7 male; R-handed: lateralization quotient: 91.40±9.75 (mean ± SD)) were included.
Participants performed a unimanual SRT and CRT task, which required responses of the dominant right index or pinky finger corresponding to a left or right green (imperative) signal visualized by an LED signaling box. TMS was used to measure SICI for the first dorsal interosseus (FDI) muscle of the right index finger. Timing of TMS pulses was semi-randomized at four different time points during each trial: during the preparation period at the presentation of the warning signal (WS; red light signal) or the imperative signal (IS), and during the action selection period at 25% or at 75% of the EMG activity onset.
Results: Preliminary results are shown for SRT and CRT in respectively figure 1 and 2. Overall, both age groups show a similar pattern and a clear inhibition during the preparation and the action selection period of the SRT and the CRT. However, as compared to younger adults, older adults showed less inhibition in the preparation and action selection period of the SRT. In the CRT there were no age-related differences in GABAergic inhibition, except for the 75% EMG reaction time (RT) condition in the younger group, where a pinky finger reaction was requested. A possible interpretation for this result might be that younger adults are able to selectively suppress the effector that is not selected for movement execution and that this is not possible for older adults due to a compromised inhibitory functionality.
Conclusion: Although inhibition profiles are similar for both SRT and CRT, older adults show less GABAergic inhibition as compared to their younger counterparts during the SRT task. In contrast, for the CRT task, there is no difference in GABAergic inhibition of the FDI between groups, except for the condition in which the pinky finger had to move in the time window just before movement initiation. We tentatively propose that younger adults might be better able to selectively suppress the effector that is not selected for movement execution.
Acknowledgements
The authors wish to thank P. Meugens and R. Clerckx (Movement Control and Neuroplasticity Research Group, Department of Kinesiology, Biomedical Sciences Group, KU Leuven , Leuven , Belgium) for their crucial assistance in respectively the development of the setup and the automatization of the data-processing.
Keywords:
transcrancial magnetic stimulation (TMS),
Short interval intracortical inhibition (SICI),
Gamma amino acid butyric acid,
Aging,
motor control
Conference:
13th National Congress of the Belgian Society for Neuroscience , Brussels, Belgium, 24 May - 24 May, 2019.
Presentation Type:
Poster presentation
Topic:
Behavioral/Systems Neuroscience
Citation:
Cuypers
K,
Hehl
M and
Swinnen
SP
(2019). Age-related changes in TMS-based gamma-aminobutyric acid (GABA) modulation during a unimanual simple and choice reaction time task..
Front. Neurosci.
Conference Abstract:
13th National Congress of the Belgian Society for Neuroscience .
doi: 10.3389/conf.fnins.2019.96.00017
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Received:
27 Apr 2019;
Published Online:
27 Sep 2019.
*
Correspondence:
Dr. Koen Cuypers, Movement Control and Neuroplasticity Research Group, Department of Kinesiology, Biomedical Sciences Group, KU Leuven, Leuven, 3000, Belgium, koen.cuypers@uhasselt.be