Diurnal Patterns of Activity of the Orienting and Executive Attention Neuronal Networks in Subjects Performing a Stroop-Like Task: A Functional Magnetic Resonance Imaging Study

Abstract

Attentional processes are fundamental to good cognitive functioning of human operators. The purpose of this study was to analyze the activity of neuronal networks involved in the orienting attention and executive control processes from the perspective of diurnal variability. Twenty-three healthy male volunteers meeting magnetic resonance (MR) inclusion criteria performed the Stroop Color-Word task (block design) in the MR scanner five times/day (06:00, 10:00, 14:00, 18:00, 22:00 h). The first scanning session was scheduled 1-1.5 h after waking. Between MR sessions, subjects performed simulated driving tasks in stable environmental conditions, with controlled physical activity and diet. Significant activation was found in brain regions related to the orienting attentional system: the parietal lobe (BA40) and frontal eye-fields (FEFs). There were also activations in areas of the executive control system: the fronto-insular cortex (FIC), dorsal anterior cingulate cortex (dACC), presupplementary motor area (preSMA), supplementary motor area (SMA), basal ganglia, middle temporal (MT; BA21), and dorsolateral prefrontal cortex (DLPFC), as a part of the central executive network. Significant deactivations were observed in the rostral anterior cingulate cortex (rACC), posterior cingulate cortex (PCC), superior frontal gyrus (SF), parietal lobe (BA39), and parahippocampal that are thought to comprise the default mode network (DMN). Additionally, the activated regions included bilaterally lingual gyrus and fusiform gyrus. The insula was bilaterally deactivated. Visual attention controlled by the goal-oriented attention system and comprising top-down and bottom-up mechanisms, activated by Stroop-like task, turned out to be prone to diurnal changes. The study results show the occurrence of time-of-day-related variations in neural activity of brain regions linked to the orienting attentional system (left parietal lobe-BA40, left and right FEFs), simultaneously providing arguments for temporal stability of the executive system and default mode network. These results also seem to suggest that the involuntary, exogenous (bottom-up) mechanism of attention is more vulnerable to circadian and fatigue factors than the voluntary (top-down) mechanism, which appear to be maintained at the same functional level during the day. The above phenomena were observed at the neural level.

Neural networks related to pro-saccades and anti-saccades revealed by independent component analysis

“…biasing, the saccade circuitry before the anti-saccade occurrence. The anterior insula has been shown to be a part of the executive system (Klein et al, 2007;Marek et al, 2010) and was found to play a role in response inhibition as well (Brass and Haggard, 2007;Swick et al, 2011). Finally, the thalamus has been associated with the definite inhibition of the prepared action and, consequently, involved in executive operations (Marzinzik and Wahl, 2008).…”

Enhanced Motor Learning in Older Adults Is Accompanied by Increased Bilateral Frontal and Fronto-Parietal Connectivity

“…The ROI approach served as a secondary exploration for our primary voxelwise PPI analysis above. In addition to the seed regions within the right DLPFC or PMd used in the primary PPI analyses, we also included regions known to be critical to the functional networks with respect to the DLPFC or the PMd, including inferior parietal cortex for the PMd-seeded networks (Keisker et al, 2009), and supplementary motor area (SMA), inferior frontal gyrus, rostral frontal area, and the contralateral (left) DLPFC for the DLPFC-seeded networks (Marek et al, 2010). Correlations between the IÀR contrast in functional connectivity and the RÀI difference in the mean RT were then tested using the Pearson's correlation method.…”

Timing is everything: Age differences in the cognitive control network are modulated by time of day.

“…Marek et al, 2010) showing time of day differences in the ability to regulate strong but incorrect responses in the orienting attentional network -a division of the task-positive network that regulates where and when attention is directed in response to external cues (Schmidt et al, 2012).…”