Dissociation between unconscious motor response facilitation and conflict in medial frontal areas

Abstract

Masked prime tasks have shown that sensory information that has not been consciously perceived can nevertheless modulate behavior. The neuronal correlates of behavioral manifestations of visuomotor priming remain debated, particularly with respect to the distribution and direction (i.e. increase or decrease) of activity changes in medial frontal areas. Here, we predicted that these discrepant results could be accounted for by two automatic and unconscious processes embedded in this task: response conflict and facilitation. We used event-related functional magnetic resonance imaging (fMRI), as 24 healthy participants had to respond, as fast as possible, to a target arrow presented immediately after a subliminal masked prime arrow. There were three experimental conditions defined by the prime-target relationship: compatible, incompatible, and neutral. The classical visuomotor priming effect was reproduced, with relatively longer reaction times (RTs) in incompatible trials. Longer RTs in incompatible than in neutral trials were specifically associated with stronger blood oxygen level-dependent (BOLD) activity in a conflict-related network comprising the anterior cingulate cortex and right frontal associative areas. Motor response facilitation as shown by shorter RTs in compatible than in neutral trials was associated with reduced activation in a motor preparation network including the medial and lateral premotor cortices, as a result of the repetition suppression of the fMRI BOLD signal. The present results provide new insights into automatic and unconscious visuomotor priming processes, suggesting an involvement of either a cognitive or motor network, depending on the prime-target relationship.

Exogenous capture of medial–frontal oscillatory mechanisms by unattended conflicting information

“…A positive correlation between the conflict-induced medial-frontal theta power and the magnitude of participant's slowdown further suggested that theta oscillations in the mPFC not only participate in the monitoring of attended conflicting events, but also may regulate inappropriate responses triggered by unattended conflicting information presented in the periphery. These findings cast doubts on traditional views which have stressed that high-level control functions of the mPFC, such as conflict-monitoring, rely exclusively on top-down and conscious processes (Dehaene et al, 2003;Jack and Shallice, 2001;Posner, 1994;Posner and DiGirolamo, 1998;Ridderinkhof et al, 2004) and give support to new evidence suggesting that mPFC control functions can potentially operate without conscious awareness (D'Ostillio and Garraux, 2012;Sumner et al, 2007;van Gaal et al, 2008;van Gaal et al, 2010b;van Gaal et al, 2011;Wang et al, 2013).…”

“…Consequently, it is possible that the mPFC responds to all kinds of non-conscious conflicting and errorprone events in a graded manner depending on the robustness of the representation of the experienced conflict (Horga and Maia, 2012). In agreement with this idea, previous studies using subliminal-priming paradigms have shown that the mPFC is sensitive to response conflict and related compensatory control processes even in conditions of reduced perceptual awareness (D'Ostillio and Garraux, 2012;Sumner et al, 2007;van Gaal et al, 2010b) and is responsive to unaware error responses (Hester et al, 2005;Nieuwenhuis et al, 2001).…”

“…4 1994; Posner and DiGirolamo, 1998;Ridderinkhof et al, 2004). However, new findings have challenged these traditional views by showing that 'high-level' functions of the prefrontal cortex such as conflict-monitoring, response inhibition and error detection can unfold without conscious awareness (D'Ostillio and Garraux, 2012;Nieuwenhuis et al, 2001;Sumner et al, 2007;van Gaal et al, 2008;van Gaal et al, 2011). To examine the influence of unconscious processing on cognitive control functions most studies have used masked-prime paradigms (see review by van Gaal et al, 2012).…”

Can the meaning of multiple words be integrated unconsciously?

“…The invisible stop signal triggered a wave of brain activity that could be tracked by electroencephalographic recordings (EEG) and functional magnetic resonance imaging deep into the 'executive networks' of the frontal cortex that are crucial for controlling our actions [1,[4][5][6]. Similarly, in recent years it has been shown that frontal executive networks of our brain can unconsciously register the occurrence of response errors [7][8][9], conflicting response alternatives [10][11][12] and competing task sets [13,14].…”

Prediction and unconscious attention operate synergistically to facilitate stimulus processing: An fMRI study

“…Under this account, unconscious attention and prediction may operate synergistically to facilitate stimulus processing. Importantly, it has been suggested that prefrontal cortical regions, particularly the dlPFC, are functionally implicated in top-down prediction and unconscious processing (Brown et al, 2008;D'Ostilio & Garraux, 2012;Walsh & Phillips, 2009). In this case, unconscious attention and prediction might interact in the dlPFC.…”