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Executive attention networks show altered relationship with default mode network in PD

View Article: PubMed Central - PubMed

ABSTRACT

Attention dysfunction is a common but often undiagnosed cognitive impairment in Parkinson's disease that significantly reduces quality of life. We sought to increase understanding of the mechanisms underlying attention dysfunction using functional neuroimaging. Functional MRI was acquired at two repeated sessions in the resting state and during the Attention Network Test, for 25 non-demented subjects with Parkinson's disease and 21 healthy controls. Behavioral and MRI contrasts were calculated for alerting, orienting, and executive control components of attention. Brain regions showing group differences in attention processing were used as seeds in a functional connectivity analysis of a separate resting state run. Parkinson's disease subjects showed more activation during increased executive challenge in four regions of the dorsal attention and frontoparietal networks, namely right frontal eye field, left and right intraparietal sulcus, and precuneus. In three regions we saw reduced resting state connectivity to the default mode network. Further, whereas higher task activation in the right intraparietal sulcus correlated with reduced resting state connectivity between right intraparietal sulcus and the precuneus in healthy controls, this relationship was absent in Parkinson's disease subjects. Our results suggest that a weakened interaction between the default mode and task positive networks might alter the way in which the executive response is processed in PD.

No MeSH data available.


Related in: MedlinePlus

Attention network test schematic showing the timing and different conditions for each trial. A trial begins by presenting one of three cue conditions for 200 ms (no cue, center cue, spatial cue). A variable delay period of 300 to 11,800 ms elapses before one of two target conditions is presented (congruent, incongruent). The target disappears after 2000 ms, or when a response button is pressed. From the moment the target appears the trial continues for a variable delay period of 3000 to 15,000 ms.
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f0010: Attention network test schematic showing the timing and different conditions for each trial. A trial begins by presenting one of three cue conditions for 200 ms (no cue, center cue, spatial cue). A variable delay period of 300 to 11,800 ms elapses before one of two target conditions is presented (congruent, incongruent). The target disappears after 2000 ms, or when a response button is pressed. From the moment the target appears the trial continues for a variable delay period of 3000 to 15,000 ms.

Mentions: All subjects performed the ANT (Fan et al., 2005) while in the MRI scanner. The ANT combines cues and targets within a single reaction time task (Fig. 2) to measure the efficiency of the alerting, orienting, and executive attention networks. We replicated the fMRI implementation of the ANT as described by Fan et al. (2005), and described here in brief. Subjects performed two scanning sessions one to three weeks apart. The purpose of acquiring two sessions was to serve as a baseline measurement for a third session taken after a cholinergic intervention, results of which are to be reported separately. Each session comprised of six separate runs, where subjects performed two buffer trials (discarded prior to analysis) followed by 36 reaction time trials (a total of 432 trials per subject). Trials consisted of a visual cue stimulus, a variable delay period, and a target stimulus. The intertrial period was also jittered. A fixation cross was presented in the center of the screen for the entire length of the run, with cue and targets superimposed. The target presented a row of five horizontal black arrows with either all arrows in the same direction (left or right; congruent condition) or with the center arrow in the opposite direction to the flanking arrows (incongruent condition). Subjects were required to press a button in their left or right hand according to the direction of the center arrow. The row of target arrows were positioned pseudorandomly with half above and half below a center fixation cross. The cue stimulus consisted of either no cue (no cue condition), a center asterisk (center cue), or an asterisk placed above or below the center fixation cross (spatial cue), in the same location as the subsequent target stimulus. Behavioral and imaging contrasts were then constructed to probe the efficiencies of the three attention networks:


Executive attention networks show altered relationship with default mode network in PD
Attention network test schematic showing the timing and different conditions for each trial. A trial begins by presenting one of three cue conditions for 200 ms (no cue, center cue, spatial cue). A variable delay period of 300 to 11,800 ms elapses before one of two target conditions is presented (congruent, incongruent). The target disappears after 2000 ms, or when a response button is pressed. From the moment the target appears the trial continues for a variable delay period of 3000 to 15,000 ms.
© Copyright Policy - CC BY
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5121155&req=5

f0010: Attention network test schematic showing the timing and different conditions for each trial. A trial begins by presenting one of three cue conditions for 200 ms (no cue, center cue, spatial cue). A variable delay period of 300 to 11,800 ms elapses before one of two target conditions is presented (congruent, incongruent). The target disappears after 2000 ms, or when a response button is pressed. From the moment the target appears the trial continues for a variable delay period of 3000 to 15,000 ms.
Mentions: All subjects performed the ANT (Fan et al., 2005) while in the MRI scanner. The ANT combines cues and targets within a single reaction time task (Fig. 2) to measure the efficiency of the alerting, orienting, and executive attention networks. We replicated the fMRI implementation of the ANT as described by Fan et al. (2005), and described here in brief. Subjects performed two scanning sessions one to three weeks apart. The purpose of acquiring two sessions was to serve as a baseline measurement for a third session taken after a cholinergic intervention, results of which are to be reported separately. Each session comprised of six separate runs, where subjects performed two buffer trials (discarded prior to analysis) followed by 36 reaction time trials (a total of 432 trials per subject). Trials consisted of a visual cue stimulus, a variable delay period, and a target stimulus. The intertrial period was also jittered. A fixation cross was presented in the center of the screen for the entire length of the run, with cue and targets superimposed. The target presented a row of five horizontal black arrows with either all arrows in the same direction (left or right; congruent condition) or with the center arrow in the opposite direction to the flanking arrows (incongruent condition). Subjects were required to press a button in their left or right hand according to the direction of the center arrow. The row of target arrows were positioned pseudorandomly with half above and half below a center fixation cross. The cue stimulus consisted of either no cue (no cue condition), a center asterisk (center cue), or an asterisk placed above or below the center fixation cross (spatial cue), in the same location as the subsequent target stimulus. Behavioral and imaging contrasts were then constructed to probe the efficiencies of the three attention networks:

View Article: PubMed Central - PubMed

ABSTRACT

Attention dysfunction is a common but often undiagnosed cognitive impairment in Parkinson's disease that significantly reduces quality of life. We sought to increase understanding of the mechanisms underlying attention dysfunction using functional neuroimaging. Functional MRI was acquired at two repeated sessions in the resting state and during the Attention Network Test, for 25 non-demented subjects with Parkinson's disease and 21 healthy controls. Behavioral and MRI contrasts were calculated for alerting, orienting, and executive control components of attention. Brain regions showing group differences in attention processing were used as seeds in a functional connectivity analysis of a separate resting state run. Parkinson's disease subjects showed more activation during increased executive challenge in four regions of the dorsal attention and frontoparietal networks, namely right frontal eye field, left and right intraparietal sulcus, and precuneus. In three regions we saw reduced resting state connectivity to the default mode network. Further, whereas higher task activation in the right intraparietal sulcus correlated with reduced resting state connectivity between right intraparietal sulcus and the precuneus in healthy controls, this relationship was absent in Parkinson's disease subjects. Our results suggest that a weakened interaction between the default mode and task positive networks might alter the way in which the executive response is processed in PD.

No MeSH data available.


Related in: MedlinePlus