The goal of the present study was to characterise precisely

The goal of the present study was to characterise precisely the spatio-temporal Ezetimibe cost dynamics of AER in children. To do so, we used magnetoencephalography (MEG) which offers a unique opportunity to investigate both the spatial and temporal brain patterns that underlie inhibitory brain mechanisms. We determined how these brain processes were modulated by an incidental exposure to negative (angry faces) vs. positive (happy faces) emotions, thus, allowing adaptive functioning in children. As MEG provides excellent time resolution and better spatial localisation than ERPs, it represents a remarkable tool for studying such complex cognitive processes (e.g., see Hari et al., 2010 for a review). The MEG analyses compared the timing and localisation of inhibition-related brain activity which occurred with incidental exposure to positive vs. negative emotional faces. Moreover, to prevent the usual confound of movement-related activity (when go and no–go trials are contrasted), we compared no–go trials associated with stimuli in an inhibitory condition to no–go trials occurring within a vigilance condition (same no–go stimuli in a non-inhibitory context) to ensure the specificity of the inhibition task effect. We hypothesised that the emotional context, particularly the presence of angry faces, would affect inhibitory brain processes and this would be expressed by greater activation in brain areas classically linked to inhibition.
Material and methods
Results
Discussion Behavioural results showed that children had more difficulty inhibiting their responses in the context of Angry than Happy faces, suggesting greater attentional regulation in the presence of aversive socio-emotional cues (Lamm and Lewis, 2010), consistent with adolescent and adult studies (Albert et al., 2010; Cohen Kadosh et al., 2014). The early sensitivity of the angular gyrus and occipital cortex to emotion regulation mechanisms (Inhibition: Angry>Happy) was unanticipated. While previous ERP studies reported a crucial role of the P100, located over posterior occipito-parietal sites, for inhibition processes or face processing (Batty and Taylor, 2006), the sensitivity of this early component to emotion regulation was not systematically reported in other EEG studies (Hum et al., 2013a,b). However, adult fMRI studies found stronger activity in the right angular gyrus when inhibition processes occurred with the incidental exposure to aversive compared to neutral pictures (Brown et al., 2012) but fMRI cannot provide information on the timing of activation. Both the P1 and the angular gyrus have been related to processes of visual attention and conflict monitoring during go/no–go tasks (Corbetta, 1998; Hillyard et al., 1998; Corbetta and Shulman, 2002; Singh-Curry and Husain, 2009; Seghier, 2013). Thus, our results suggest that the early activity in the right angular gyrus may reflect neural recruitment to meet the higher visual attention demands required to mediate impulse control due to the emotional context. The combination of high temporal and spatial resolution provided by our MEG study, also helped clarify the N2 generators, reported as a key component of inhibition and emotion regulation processes by several ERP studies (e.g., Lewis et al., 2007; Todd et al., 2008). In particular, our results showed that the incidental exposure to Angry compared to Happy faces was associated with stronger, longer-lasting brain inhibition-related activations in the right OFG from 225 to 325ms. Worth noticing, activations reported in the orbito-frontal gyrus were the only ones surviving the correction for multiple comparisons threshold (p<0.05 corrected), other activations discussed here were significant at p<0.005 uncorrected (see Table 1 in bold). The OFG is known to be modulated by interactions between response inhibition (go/no–go task) and stimulus valence, both in children (Todd et al., 2012) and adults (Shafritz et al., 2006; Goldstein et al., 2007). Moreover, convergent research studies indicate that the orbitofrontal region evaluates and regulates how emotion influences control mechanisms which guide ongoing actions (Pessoa, 2009) and, thus plays an important role in flexible social behaviour [for reviews see, Schoenbaum et al., 2009; Nelson and Guyer, 2011]. For instance, it has been shown that the OFG is implicated in evaluating the degree of control required to modify or inhibit actions elicited by the facial expression (e.g., unpleasant or discouraging) in children (Blair et al., 1999; Todd et al., 2012). Our results suggest that OFG-related changes in amplitude associated with inhibition processes occurring from 225 to 325ms after no-go (inhibitory) trials would help guide further behaviour in response to facial expressions (i.e., towards action vs. inaction). In addition, our results showed that automatic emotion regulation processes related to the OFG were right lateralized. This is consistent with adult studies showing that negative affect (see Davidson, 2004) or avoidance behaviour (Harmon-Jones, 2004) will trigger greater right-lateralized frontal responses. As well, earlier studies of facial affect in children which also showed right-lateralised OFG activity (Todd et al., 2008, 2012).