Grammatical and resource components of sentence processing in Parkinson's disease: An fMRI study

Sentence comprehension is a complex process involving at least a grammatical processor and a procedural component that supports language computations. One type of cerebral architecture that may underlie sentence processing is a network of distributed brain regions. We report two experiments designed to evaluate the cognitive and physiological substrate of sentence processing diaculties in nondemented patients with Parkinson's disease (PD). In the first experiment, patients answered simple questions about sentences that varied in their computational demands. Group and individual patient analyses indicated that PD patients are significantly compromised on this task, and that their difficulties become more prominent as the computational demands of the sentences increase. We manipulated the set of sentences to stress performance aspects of sentence processing. PD patients were compromised in their ability to detect errors in the presence and nature of a sentence's grammatical morphemes, suggesting a deficit in selective attention, but their ability to answer questions about a sentence was not afFected by short-term memory factors. In the second experiment, positron emission tomography was used to correlate this pattern of sentence comprehension impairment with regional cerebral glucose metabolism (rCMRgl) obtained at rest in a representative subset of these PD patients. Grammatical comprehension and attention in sentence processing correlated significantly with mesial frontal rCMRgl. Regression analyses confirmed the central role of left mesial frontal cortex, and identified a subsidiary role for left caudate in overall sentence comprehension, for left dorsolateral frontal cortex in grammatical processing, and for bilateral dorsolateral frontal cortex in attending to the presence of grammatical features. We conclude that compromised mesial frontal functioning underlies in part the sentence processing deficit of these patients, and these data illustrate one method for mapping portions of a sentence processing mechanism onto a distributed cerebral architecture.

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The Neural Correlates of Spatial and Object Working Memory in Elderly and Parkinson’s Disease Subjects

Behavioural Neurology ◽

10.1155/2015/123636 ◽

2015 ◽

Vol 2015 ◽

pp. 1-10 ◽

Cited By ~ 6

Author(s):

Silvia P. Caminiti ◽

Chiara Siri ◽

Lucia Guidi ◽

Angelo Antonini ◽

Daniela Perani

Keyword(s):

Parkinson’S Disease ◽

Working Memory ◽

Parkinson's Disease ◽

Neural Correlates ◽

Elderly Subjects ◽

Task Execution ◽

Compensatory Mechanisms ◽

Frontoparietal Network ◽

Fmri Study ◽

Comparable Performance

This fMRI study deals with the neural correlates of spatial and objects working memory (SWM and OWM) in elderly subjects (ESs) and idiopathic Parkinson’s disease (IPD). Normal aging and IPD can be associated with a WM decline. In IPD population, some studies reported similar SWM and OWM deficits; others reported a greater SWM than OWM impairment. In the present fMRI research, we investigated whether compensated IPD patients and elderly subjects with comparable performance during the execution of SWM and OWM tasks would present differences in WM-related brain activations. We found that the two groups recruited a prevalent left frontoparietal network when performing the SWM task and a bilateral network during OWM task execution. More specifically, the ESs showed bilateral frontal and subcortical activations in SWM, at difference with the IPD patients who showed a strict left lateralized network, consistent with frontostriatal degeneration in IPD. The overall brain activation in the IPD group was more extended as number of voxels with respect to ESs, suggesting underlying compensatory mechanisms. In conclusion, notwithstanding comparable WM performance, the two groups showed consistencies and differences in the WM activated networks. The latter underline the compensatory processes of normal typical and pathological aging.

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