Attentional control: Temporal relationships within the fronto-parietal network

Department of Psychology, George Washington University, Washington, DC 20015, United States.
Neuropsychologia (Impact Factor: 3.3). 02/2012; 50(6):1202-10. DOI: 10.1016/j.neuropsychologia.2012.02.009
Source: PubMed


Selective attention to particular aspects of incoming sensory information is enabled by a network of neural areas that includes frontal cortex, posterior parietal cortex, and, in the visual domain, visual sensory regions. Although progress has been made in understanding the relative contribution of these different regions to the process of visual attentional selection, primarily through studies using neuroimaging, rather little is known about the temporal relationships between these disparate regions. To examine this, participants viewed two rapid serial visual presentation (RSVP) streams of letters positioned to the left and right of fixation point. Before each run, attention was directed to either the left or the right stream. Occasionally, a digit appeared within the attended stream indicating whether attention was to be maintained within the same stream ('hold' condition) or to be shifted to the previously ignored stream ('shift' condition). By titrating the temporal parameters of the time taken to shift attention for each participant using a fine-grained psychophysics paradigm, we measured event-related potentials time-locked to the initiation of spatial shifts of attention. The results revealed that shifts of attention were evident earlier in the response recorded over frontal than over parietal electrodes and, importantly, that the early activity over frontal electrodes was associated with a successful shift of attention. We conclude that frontal areas are engaged early for the purpose of executing an attentional shift, likely triggering a cascade through the fronto-parietal network ultimately, resulting in the attentional modulation of sensory events in posterior cortices.

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    • "It has been suggested that the FPN and VN cooperate to support visual attention [97]. A pioneering study revealed that visual cortical areas that selectively process relevant information are functionally connected with the FPN [98], which is associated with top-down enhancement of task-relevant stimuli [72]. "
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  • No preview · Article · May 2012 · Neuropsychologia
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    ABSTRACT: Background Previous studies have demonstrated task-dependent functional interactions of a frontal–parietal control system with the competing dorsal attention (DA) and default mode networks (DM). However, evidence suggests that the frontal–parietal control system is functionally heterogeneous, consisting of two distinct sub-networks that demonstrate dissociable intrinsic functional connectivity (FC) patterns: a frontal–parietal “executive control network” (CON) and a cingulo-opercular “salience network” (SAL). In this study, we aimed to test the hypothesis that CON and SAL would show dissociable task-dependent changes in connectivity with regard to the competing DA and DM when switching from rest to external task performance. Methods Nineteen healthy adults underwent four functional MRI scans: two during rest and two while performing a global–local selective attention task. Seed-based FC defined the CON and SAL. Connectivity changes between task and rest states were assessed by analysis of variance. The relationship of task-dependent changes in connectivity for each of these networks with behavioral measures was also characterized. Results CON and SAL demonstrated distinct stable and task-dependent regional connectivity. Whereas CON primarily increased FC with visual cortex regions associated with the DA during task performance versus rest, the SAL increased coupling with regions belonging to the DM. Greater dissociation between CON and SAL and between regions with which they coupled during task was associated with better task accuracy. Conclusions The divergent task-dependent dynamics of CON and SAL connectivity with the anti-correlated DA and DM support distinct functional roles of these two “control” networks.
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