Academic journal article Cognitive, Affective and Behavioral Neuroscience

Dissociable Yet Tied Inhibitory Processes: The Structure of Inhibitory Control

Academic journal article Cognitive, Affective and Behavioral Neuroscience

Dissociable Yet Tied Inhibitory Processes: The Structure of Inhibitory Control

Article excerpt

Published online: 10 January 2014

© Psychonomic Society, Inc. 2014

Abstract Cognitive and neural models have proposed the existence of a single inhibitory process that regulates behavior and depends on the right frontal operculum (rFO). The aim of this study was to make a contribution to the ongoing debate as to whether inhibition is a single process or is composed of multiple, independent processes. Here, within a single paradigm, we assessed the links between two inhibitory phenomena-namely, resistance to involuntary visual capture by abrupt onsets and resolving of spatial stimulus-response conflict. We did so by conducting three experiments, two involving healthy volunteers (Exps. 1 and 3), and one with the help of a well-documented patient, R.J., with selectively weakened inhibition following a lesion of the rFO. The results suggest that resistance to capture and stimulus-response conflict are independent, because (a) additive effects were found (Exps. 1 and 3), (b) capture did not correlate with compatibility effects (Exp. 1), (c) dual tasking affected the two phenomena differently (Exp. 3), and (d) a dissociation was found between the two in patient R.J. (Exp. 2). However, the results also show that these two phenomena may share some processing components, given that (a) both were affected in patient R.J., but to different degrees (Exp. 2), and (b) increasing the difficulty of dual tasking produced an increasingly negative correlation between capture and compatibility (Exp. 3), which suggests that when resources are withdrawn from the control of the former, they are used to control the latter.

Keywords Inhibition . Attentional capture . Stimulus- response compatibility . Dual task . Inferior frontal gyrus . Frontal operculum

The abilities to avoid being distracted by irrelevant items and to put a stop to undesired or incorrect actions are fundamental for everyday regulation of coherent and appropriate behavior. The question of whether multiple independent inhibitory processes or just one such process orchestrates behavior is the subject of ongoing debate. In a comprehensive review, Kok (1999) concluded that different kinds of inhibition might exist, with inhibition being organized in the form of a hierarchical network including different sections of the brain. His evidence stemmed from psychophysical, developmental, and electrophysiological studies conducted with the aid of a variety of paradigms. The diversity of inhibitory processes is a conclusion that has also been drawn in other reviews (Dagenbach & Carr, 1994; Dempster & Brainerd, 1995; Nee, Wager, & Jonides, 2007) and in empirical studies that have reported very low correlations among tasks supposed to involve inhibition (e.g., Casey et al., 2000; Fan, Flombaum, McCandliss, Thomas, & Posner, 2003; Kramer, Humphrey, Larish, & Logan, 1994; Shilling, Chetwynd, & Rabbitt, 2002; Simon & Berbaum, 1990). The rather constant lack of such a correlation has been interpreted as evidence that different inhibition tasks call upon fundamentally different kinds of conflict resolution processes. It has also been suggested that, in such cases, these processes should not relate to each other, because they apply independently to several information-processing streams (Fan et al., 2003). In a comprehensive meta-analysis of neuroimaging tasks, Nee et al. found that the activations in different inhibition tasks overlapped in a number of brain areas, but that there were also task-specific activations. The authors proposed that different inhibitory processes act on different stages of processing. However, the results of neuropsychological and brain-imaging studies have suggested that only one inhibitory process may regulate behavior (Aron, Fletcher, Bullmore, Sahakian, & Robbins, 2003; Konishi et al., 1999; Stelzel, Schumacher, Schubert, & D'Esposito, 2006), an idea also adopted by a number of neuroanatomical and cognitive models (Aron, 2007, 2011; Aron, Robbins, & Poldrack, 2004; Michael, Garcia, Fernandez, Sellal, & Boucart, 2006; Michael, Lété, & Ducrot, 2013; Watson & Humphreys, 1997). …

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