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Attentional set-shifting deficit in Parkinson's disease is associated with prefrontal dysfunction: an FDG-PET study.

Sawada Y, Nishio Y, Suzuki K, Hirayama K, Takeda A, Hosokai Y, Ishioka T, Itoyama Y, Takahashi S, Fukuda H, Mori E - PLoS ONE (2012)

Bottom Line: Although several neuroimaging studies have addressed this issue, the results of these studies were confounded by the use of tasks that required other cognitive processes in addition to set-shifting, such as rule learning and working memory.Shift cost, which is a measure of attentional set-shifting ability, was significantly correlated with hypometabolism in the right dorsolateral prefrontal cortex, including the putative human frontal eye field.Our results provide direct evidence that dysfunction in the dorsolateral prefrontal cortex makes a primary contribution to the attentional set-shifting deficit that has been observed in PD patients.

View Article: PubMed Central - PubMed

Affiliation: Department of Behavioral Neurology and Cognitive Neuroscience, Tohoku University Graduate School of Medicine, Sendai, Japan.

ABSTRACT
The attentional set-shifting deficit that has been observed in Parkinson's disease (PD) has long been considered neuropsychological evidence of the involvement of meso-prefrontal and prefrontal-striatal circuits in cognitive flexibility. However, recent studies have suggested that non-dopaminergic, posterior cortical pathologies may also contribute to this deficit. Although several neuroimaging studies have addressed this issue, the results of these studies were confounded by the use of tasks that required other cognitive processes in addition to set-shifting, such as rule learning and working memory. In this study, we attempted to identify the neural correlates of the attentional set-shifting deficit in PD using a compound letter task and 18F-fluoro-deoxy-glucose (FDG) positron emission tomography during rest. Shift cost, which is a measure of attentional set-shifting ability, was significantly correlated with hypometabolism in the right dorsolateral prefrontal cortex, including the putative human frontal eye field. Our results provide direct evidence that dysfunction in the dorsolateral prefrontal cortex makes a primary contribution to the attentional set-shifting deficit that has been observed in PD patients.

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Related in: MedlinePlus

Schematic illustrations of the psychophysical tasks.In both the Global and Local tasks, compound letter stimuli appeared after a 2-second presentation of a visual cue that indicated whether the target was a global or local letter. The subjects were instructed to respond orally to the target component of each compound letter stimulus as quickly as possible. In these tasks, the subjects maintained their attention on a single component of the compound letters (either the local or global component of the stimuli), and they were not required to reorient their attention. However, in the Mixed task, the cue that indicated the target component of the compound letter changed from trial to trial in a pseudorandom manner. The task required that the subjects switch their attention on the basis of the cue that was presented to them on each trial.
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pone-0038498-g001: Schematic illustrations of the psychophysical tasks.In both the Global and Local tasks, compound letter stimuli appeared after a 2-second presentation of a visual cue that indicated whether the target was a global or local letter. The subjects were instructed to respond orally to the target component of each compound letter stimulus as quickly as possible. In these tasks, the subjects maintained their attention on a single component of the compound letters (either the local or global component of the stimuli), and they were not required to reorient their attention. However, in the Mixed task, the cue that indicated the target component of the compound letter changed from trial to trial in a pseudorandom manner. The task required that the subjects switch their attention on the basis of the cue that was presented to them on each trial.

Mentions: Three different compound letter decision tasks were administered: the Global, Local, and Mixed tasks (Figure 1). Each subject completed five training trials and 24 test trials for each of the three tasks. The orders of the Global and Local tasks were counterbalanced between subjects. Visual stimuli were presented in the center of either a 17- or 15-inch liquid crystal display that was located at a distance of 70 cm from the subject. Two different compound letter stimuli were used throughout the tasks; one was a global “” that consisted of local “”s, and the other was a global “” that consisted of local “”s (“” and “” are both Japanese Kana (phonographic characters). In each of the compound letter stimuli, a global letter (8.0 cm×8.0 cm, which subtended 6.5 degrees of visual angle) was composed of 11 small local letters (1.0 cm×1.0 cm, which subtended 0.8 degrees of visual angle). Subjects were instructed to read either the global letter or the local letter that was embedded in a compound letter stimulus aloud in accordance with the identity of a preceding cue as quickly as possible. Their oral responses were digitally recorded, and the reaction time (RT) of each trial was measured as the time between the onset of the visual stimulus and the onset of the oral response.


Attentional set-shifting deficit in Parkinson's disease is associated with prefrontal dysfunction: an FDG-PET study.

Sawada Y, Nishio Y, Suzuki K, Hirayama K, Takeda A, Hosokai Y, Ishioka T, Itoyama Y, Takahashi S, Fukuda H, Mori E - PLoS ONE (2012)

Schematic illustrations of the psychophysical tasks.In both the Global and Local tasks, compound letter stimuli appeared after a 2-second presentation of a visual cue that indicated whether the target was a global or local letter. The subjects were instructed to respond orally to the target component of each compound letter stimulus as quickly as possible. In these tasks, the subjects maintained their attention on a single component of the compound letters (either the local or global component of the stimuli), and they were not required to reorient their attention. However, in the Mixed task, the cue that indicated the target component of the compound letter changed from trial to trial in a pseudorandom manner. The task required that the subjects switch their attention on the basis of the cue that was presented to them on each trial.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3369918&req=5

pone-0038498-g001: Schematic illustrations of the psychophysical tasks.In both the Global and Local tasks, compound letter stimuli appeared after a 2-second presentation of a visual cue that indicated whether the target was a global or local letter. The subjects were instructed to respond orally to the target component of each compound letter stimulus as quickly as possible. In these tasks, the subjects maintained their attention on a single component of the compound letters (either the local or global component of the stimuli), and they were not required to reorient their attention. However, in the Mixed task, the cue that indicated the target component of the compound letter changed from trial to trial in a pseudorandom manner. The task required that the subjects switch their attention on the basis of the cue that was presented to them on each trial.
Mentions: Three different compound letter decision tasks were administered: the Global, Local, and Mixed tasks (Figure 1). Each subject completed five training trials and 24 test trials for each of the three tasks. The orders of the Global and Local tasks were counterbalanced between subjects. Visual stimuli were presented in the center of either a 17- or 15-inch liquid crystal display that was located at a distance of 70 cm from the subject. Two different compound letter stimuli were used throughout the tasks; one was a global “” that consisted of local “”s, and the other was a global “” that consisted of local “”s (“” and “” are both Japanese Kana (phonographic characters). In each of the compound letter stimuli, a global letter (8.0 cm×8.0 cm, which subtended 6.5 degrees of visual angle) was composed of 11 small local letters (1.0 cm×1.0 cm, which subtended 0.8 degrees of visual angle). Subjects were instructed to read either the global letter or the local letter that was embedded in a compound letter stimulus aloud in accordance with the identity of a preceding cue as quickly as possible. Their oral responses were digitally recorded, and the reaction time (RT) of each trial was measured as the time between the onset of the visual stimulus and the onset of the oral response.

Bottom Line: Although several neuroimaging studies have addressed this issue, the results of these studies were confounded by the use of tasks that required other cognitive processes in addition to set-shifting, such as rule learning and working memory.Shift cost, which is a measure of attentional set-shifting ability, was significantly correlated with hypometabolism in the right dorsolateral prefrontal cortex, including the putative human frontal eye field.Our results provide direct evidence that dysfunction in the dorsolateral prefrontal cortex makes a primary contribution to the attentional set-shifting deficit that has been observed in PD patients.

View Article: PubMed Central - PubMed

Affiliation: Department of Behavioral Neurology and Cognitive Neuroscience, Tohoku University Graduate School of Medicine, Sendai, Japan.

ABSTRACT
The attentional set-shifting deficit that has been observed in Parkinson's disease (PD) has long been considered neuropsychological evidence of the involvement of meso-prefrontal and prefrontal-striatal circuits in cognitive flexibility. However, recent studies have suggested that non-dopaminergic, posterior cortical pathologies may also contribute to this deficit. Although several neuroimaging studies have addressed this issue, the results of these studies were confounded by the use of tasks that required other cognitive processes in addition to set-shifting, such as rule learning and working memory. In this study, we attempted to identify the neural correlates of the attentional set-shifting deficit in PD using a compound letter task and 18F-fluoro-deoxy-glucose (FDG) positron emission tomography during rest. Shift cost, which is a measure of attentional set-shifting ability, was significantly correlated with hypometabolism in the right dorsolateral prefrontal cortex, including the putative human frontal eye field. Our results provide direct evidence that dysfunction in the dorsolateral prefrontal cortex makes a primary contribution to the attentional set-shifting deficit that has been observed in PD patients.

Show MeSH
Related in: MedlinePlus