İnhibitör kontrolün GABAerjik ve glutamaterjik reseptörle ilişkisi: Kortikal uyarilabilirlik ve durdurma sinyali görevi performansindan elde edilen bulgular

Inhibitory control, a core component of executive functions (EFs), is the ability to regulate attention, behavior, thoughts, and emotions to override automatic or prepotent responses. It enables individuals to resist distractions, delay gratification, and adapt to changing goals or environments. Inhibitory control operates at multiple levels, including interference control (suppressing irrelevant stimuli) and cognitive inhibition (resisting unwanted thoughts or memories). Neural mechanisms underlying inhibitory control involve GABAergic and glutamatergic processes in the motor cortex, which can be measured via Transcranial Magnetic Stimulation (TMS). While GABAergic inhibition has been linked to inhibition control, the relationship between cortical excitability and broader cognitive control remains unclear. This study seeks to deepen understanding of how cortical excitability influences inhibitory processes across age groups and individual differences. Forty-eight healthy participants underwent a TMS session to assess cortical excitability, measuring Short-Interval Intracortical Inhibition (SICI), Intracortical Facilitation (ICF), and Short-Latency Afferent Inhibition (SAI). Participants also completed cognitive tasks, including the Stroop Task, Flanker Task, and Stop-Signal Task (SST), to evaluate cognitive control performance. Behavioral metrics such as reaction time (RT), stop-signal delay (SSD), and stop-signal reaction time (SSRT) were recorded. Data analysis showed, faster RT in congruent trials of the Stroop task was correlated with stronger SICI 3 ms. (r = 0.38, p = 0.04), and faster RT in-congruent trials of the Flanker task was correlated with reduced ICF 12 ms. (r = 0.33, p = 0.03). Furthermore, for SST: shorter SSD correlated with decreased CSP (r = 0.33, p = 0.04), increased SICI 2 ms. (r = -0.42, p = 0.012), and increased ICF at 10 ms (r = -0.38, p = 0.017) and 12 ms (r = -0.37, p = 0.023), on the other hand, faster SSRT correlated with increased SAI 20 ms. (r = 0.34, p = 0.044). Finally, group comparisons revealed Good Inhibitors demonstrated significantly higher SICI at 2 ms (p = 0.019) and ICF at 10 ms (p = 0.03), and 12 ms (p = 0.044), than Poor Inhibitors. Fast SSRT individuals showed increased SAI at 20 ms (p = 0.035) compared to Slow SSRT individuals. Age correlated with Flanker RT (r = 0.40, p = 0.01), but no other age-related effects were significant. The study underscores the dynamic interplay between GABAergic inhibition and glutamatergic facilitation in inhibitory control performance. GABAergic inhibition is essential for optimizing brain function by suppressing irrelevant or competing neural activity, thereby refining signal processing and behavioral responses. Conversely, glutamatergic facilitation enhances cortical excitability, priming motor circuits for rapid engagement and enhancing the readiness of inhibitory processes.