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| Research article summary (published 8 Mar 2009): |
Mild cognitive impairment: loss of linguistic task-induced changes in motor cortex excitability.
Full Abstract
BACKGROUND: In amnestic mild cognitive impairment (aMCI), functional neuronal connectivity may be altered, as suggested by quantitative EEG and neuroimaging data. In young healthy humans, the execution of linguistic tasks modifies the excitability of the hand area of the dominant primary motor cortex (M1(hand)), as tested by transcranial magnetic stimulation (TMS). We used TMS to investigate functional connectivity between language-related cortical areas and M1(hand) in aMCI. METHODS: Ten elderly women with aMCI and 10 age-matched women were recruited. All participants were right handed and underwent a neuropsychological evaluation. In the first TMS experiment, participants performed three different tasks: reading aloud, viewing of non-letter strings (baseline), and nonverbal oral movements. The second experiment included the baseline condition and three visual searching/matching tasks using letters, geometric shapes, or digits as target stimuli. RESULTS: In controls, motor evoked potentials (MEP) elicited by suprathreshold TMS of the left M1(hand) were significantly larger during reading aloud (170% baseline) than during nonverbal oral movements, whereas no difference was seen for right M1(hand) stimulation. Similarly, MEP elicited by left M1(hand) stimulation during letter and shape searching/matching tasks were significantly larger compared to digit task. In contrast, linguistic task performance did not produce any significant MEP modulation in patients with aMCI, although neuropsychological evaluation showed normal language abilities. CONCLUSIONS: Findings suggest that functional connectivity between the language-related brain regions and the dominant M1(hand) may be altered in amnestic mild cognitive impairment. Follow-up studies will reveal whether transcranial magnetic stimulation application during linguistic tasks may contribute to characterize the risk of conversion to Alzheimer disease.
Author information
Author/s: Bracco, L (L); Giovannelli, F (F); Bessi, V (V); Borgheresi, A (A); Di Tullio, A (A); Sorbi, S (S); Zaccara, G (G); Cincotta, M (M);
Affiliation: Department of Neurological and Psychiatric Sciences, University of Florence, Florence Health Authority, Florence, Italy.
Journal and publication information
Publication Type: Journal Article; Research Support, Non-U.S. Gov't
Journal: Neurology (Neurology), published in United States. (Language: eng)
Reference: 2009-Mar; vol 72 (issue 10) : pp 928-34
Dates: Created 2009/03/10; Completed 2009/04/10;
PMID: 19273828, status: MEDLINE (last retrieval date: 4/10/2009, IMS Date: 10 Apr 2009 00:00:00)
Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.
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