Differential patterns of functional and structural plasticity within and between inferior frontal gyri support training‐induced improvements in inhibitory control proficiency

Abstract

Ample evidence indicates that inhibitory control (IC), a key executive component referring to the ability to suppress cognitive or motor processes, relies on a right-lateralized fronto-basal brain network. However, whether and how IC can be improved with training and the underlying neuroplastic mechanisms remains largely unresolved. We used functional and structural magnetic resonance imaging to measure the effects of 2 weeks of training with a Go/NoGo task specifically designed to improve frontal top-down IC mechanisms. The training-induced behavioral improvements were accompanied by a decrease in neural activity to inhibition trials within the right pars opercularis and triangularis, and in the left pars orbitalis of the inferior frontal gyri. Analyses of changes in brain anatomy induced by the IC training revealed increases in grey matter volume in the right pars orbitalis and modulations of white matter microstructure in the right pars triangularis. The task-specificity of the effects of training was confirmed by an absence of change in neural activity to a control working memory task. Our combined anatomical and functional findings indicate that differential patterns of functional and structural plasticity between and within inferior frontal gyri enhanced the speed of topdown inhibition processes and in turn IC proficiency. The results suggest that training-based interventions might help overcoming the anatomic and functional deficits of inferior frontal gyri manifesting in inhibition-related clinical conditions. More generally, we demonstrate how multimodal neuroimaging Additional Supporting Information may be found in the online version of this article.

Enhancing frontal top-down inhibitory control with Go/NoGo training

“…However, while a reinforcement of frontal inhibitory mechanisms has been demonstrated following short training with a stop-signal task, only one study found corresponding effects after training with a Go/NoGo task with varying S-R mapping rules (Chavan et al 2015). These authors showed that 2 weeks of such training yielded a decrease in the neural activity within the left and right IFG, as well as changes in both grey and white matter frontal microstructure.…”

“…10-15 h in Thorell et al 2009;Johnstone et al 2012;Berkman et al 2014;Chavan et al 2015). For example, training IC with stop-signal tasks (SST) or Go/ NoGo tasks has been found to decrease stop-signal reaction times (SSRT; Guerrieri et al 2012;Manuel et al 2013), or to decrease false alarm rate and/or response time in the trained task, respectively (Schapkin et al 2007;Manuel et al 2010;Johnstone et al 2012;Benikos et al 2013).…”

“…A few studies, however, did not find such a decrease (e.g., Cohen and Poldrack, 2008), or only in some conditions (Ditye et al 2012). These patterns of behavioral improvements have been hypothesized to follow from improvements in the speed of inhibition processes (White et al 2014;Chavan et al 2015).…”

“…Functional neuroimaging studies revealed that traininginduced improvements in IC were supported by plastic modifications within the cortico-subcortical inhibitory control brain network (inferior frontal gyri, pre-supplementary motor area and basal ganglia; IFG, SMA, and BG, respectively; Manuel et al 2013;Berkman et al 2014;Chavan et al 2015) according to two distinct, non-exclusive neurocognitive mechanisms.…”

“…Second, inhibitory control performance improvement can be achieved via the enhancement of controlled topdown inhibition processes Chavan et al 2015): when the task used to train IC is designed to prevent automatic inhibition to develop, i.e., with varying S-R mapping rules, controlled fronto-basal IC neurocognitive mechanisms are repeatedly solicited during the training and thus ultimately enhanced Spierer et al 2013;Chavan et al 2015). Neurophysiologically, such optimizations of frontal inhibition processes have been shown to manifest as decreases in the activity of right inferior frontal cortices around 200 ms to 300 ms after the onset of stop stimuli (Benikos et al 2013).…”