Alzheimer's disease (AD) is characterized by altered functional cortico-cortical connectivity likely due to loss of afferent and efferent connections between different cortical areas. Here we explored parieto-frontal functional connectivity in 15 AD patients and 12 healthy control subjects by means of bifocal transcranial magnetic stimulation (TMS). Conditioning stimuli were applied over the right posterior parietal cortex (PPC) at different intensities (90% and 110% of resting motor threshold, RMT). Motor evoked potentials (MEPs) were then recorded from the ipsilateral primary motor cortex at different interstimulus intervals (ISIs) ranging between 2 and 15 ms. Results showed that in healthy subjects, a conditioning TMS pulse applied over the ipsilateral PPC at 90%, but not at 110%, of RMT intensity was able to increase the excitability of the right M1. This functional interaction peaked at ISI = 6 ms. Conversely, in AD patients the facilitatory pattern of parieto-motor connections was evident only when TMS was delivered at an intensity of 110% of RMT with a peak at ISI = 8 ms. Moreover in AD patients, treatment with cholinesterase inhibitors did not induce any significant modification in the strength of the connection. In subsequent analyses, we found that, in AD patients, the effects induced by PPC conditioning at 110% RMT correlated with neuropsychological measures of episodic memory and executive functions, implying that patients with better cognitive performance had less impaired connectivity. Our findings reveal that parieto-frontal cortico-cortical functional connectivity is altered in AD patients, providing further evidence for a disconnection-based interpretation of AD symptoms. © 2013 - IOS Press and the authors. All rights reserved

Bonnì, S., Lupo, F., LO GERFO, E., Martorana, A., Perri, R., Caltagirone, C., et al. (2013). Altered parietal-motor connections in Alzheimer's disease patients. JOURNAL OF ALZHEIMER'S DISEASE, 33(2), 525-533 [10.3233/JAD-2012-121144].

Altered parietal-motor connections in Alzheimer's disease patients

LO GERFO, EMANUELE;
2013

Abstract

Alzheimer's disease (AD) is characterized by altered functional cortico-cortical connectivity likely due to loss of afferent and efferent connections between different cortical areas. Here we explored parieto-frontal functional connectivity in 15 AD patients and 12 healthy control subjects by means of bifocal transcranial magnetic stimulation (TMS). Conditioning stimuli were applied over the right posterior parietal cortex (PPC) at different intensities (90% and 110% of resting motor threshold, RMT). Motor evoked potentials (MEPs) were then recorded from the ipsilateral primary motor cortex at different interstimulus intervals (ISIs) ranging between 2 and 15 ms. Results showed that in healthy subjects, a conditioning TMS pulse applied over the ipsilateral PPC at 90%, but not at 110%, of RMT intensity was able to increase the excitability of the right M1. This functional interaction peaked at ISI = 6 ms. Conversely, in AD patients the facilitatory pattern of parieto-motor connections was evident only when TMS was delivered at an intensity of 110% of RMT with a peak at ISI = 8 ms. Moreover in AD patients, treatment with cholinesterase inhibitors did not induce any significant modification in the strength of the connection. In subsequent analyses, we found that, in AD patients, the effects induced by PPC conditioning at 110% RMT correlated with neuropsychological measures of episodic memory and executive functions, implying that patients with better cognitive performance had less impaired connectivity. Our findings reveal that parieto-frontal cortico-cortical functional connectivity is altered in AD patients, providing further evidence for a disconnection-based interpretation of AD symptoms. © 2013 - IOS Press and the authors. All rights reserved
Articolo in rivista - Articolo scientifico
Alzheimer's disease; connectivity; parietal cortex; transcranial magnetic stimulation; Aged; Aged, 80 and over; Alzheimer Disease; Cholinesterase Inhibitors; Efferent Pathways; Evoked Potentials, Motor; Female; Humans; Male; Motor Cortex; Neuropsychological Tests; Parietal Lobe; Phenylcarbamates; Transcranial Magnetic Stimulation; Psychiatry and Mental Health; Geriatrics and Gerontology; Clinical Psychology
English
2013
33
2
525
533
none
Bonnì, S., Lupo, F., LO GERFO, E., Martorana, A., Perri, R., Caltagirone, C., et al. (2013). Altered parietal-motor connections in Alzheimer's disease patients. JOURNAL OF ALZHEIMER'S DISEASE, 33(2), 525-533 [10.3233/JAD-2012-121144].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/66226
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