title: Improving ideomotor limb apraxia by electrical stimulation of the left posterior parietal cortex.
abstract: Limb apraxia, a deficit of planning voluntary gestures, is most frequently caused by damage to the left hemisphere, where, according to an influential neurofunctional model, gestures are planned, before being executed through the motor cortex of the hemisphere contralateral to the acting hand. We used anodal transcranial direct current stimulation delivered to the left posterior parietal cortex (PPC), the right motor cortex (M1), and a sham stimulation condition, to modulate the ability of six left-brain-damaged patients with ideomotor apraxia, and six healthy control subjects, to imitate hand gestures, and to perform skilled hand movements using the left hand. Transcranial direct current stimulation delivered to the left PPC reduced the time required to perform skilled movements, and planning, but not execution, times in imitating gestures, in both patients and controls. In patients, the amount of decrease of planning times brought about by left PPC transcranial direct current stimulation was influenced by the size of the parietal lobe damage, with a larger parietal damage being associated with a smaller improvement. Of interest from a clinical perspective, left PPC stimulation also ameliorated accuracy in imitating hand gestures in patients. Instead, transcranial direct current stimulation to the right M1 diminished execution, but not planning, times in both patients and healthy controls. In conclusion, by using a transcranial stimulation approach, we temporarily improved ideomotor apraxia in the left hand of left-brain-damaged patients, showing a role of the left PPC in planning gestures. This evidence opens up novel perspectives for the use of transcranial direct current stimulation in the rehabilitation of limb apraxia.
authors.affiliation: 1 Department of Psychology and NeuroMI-Milan Centre for Neuroscience, University of Milano-Bicocca, Milan, Italy 2 Laboratory of Neuropsychology, IRCSS Italian Auxological Institute, Milan, Italy.
authors.forename: Nadia
authors.initials: N
authors.lastname: Bolognini
authors.affiliation: 1 Department of Psychology and NeuroMI-Milan Centre for Neuroscience, University of Milano-Bicocca, Milan, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Convento
authors.affiliation: 2 Laboratory of Neuropsychology, IRCSS Italian Auxological Institute, Milan, Italy 3 Department of Neurorehabilitation Sciences, IRCCS Italian Auxological Institute, Milan, Italy.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Banco
authors.affiliation: 4 SSVD Neuropsychology Unit, Department of Neurological Science and Vision, Spedali Civili, Brescia, Italy.
authors.forename: Flavia
authors.initials: F
authors.lastname: Mattioli
authors.affiliation: 3 Department of Neurorehabilitation Sciences, IRCCS Italian Auxological Institute, Milan, Italy 5 Department of Biomedical Sciences for Health, University of Milan, Milan, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Tesio
authors.affiliation: 1 Department of Psychology and NeuroMI-Milan Centre for Neuroscience, University of Milano-Bicocca, Milan, Italy 2 Laboratory of Neuropsychology, IRCSS Italian Auxological Institute, Milan, Italy giuseppe.vallar@unimib.it.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Vallar
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D020240:Apraxia, Ideomotor / Q000523:psychology / Q000628:therapy*; D056344:Executive Function; D005260:Female; D007839:Functional Laterality; D005868:Gestures; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex; D010296:Parietal Lobe; D011597:Psychomotor Performance; D013060:Speech; D020521:Stroke / Q000628:therapy; D065908:Transcranial Direct Current Stimulation / Q000379:methods*
keywords: apraxia; motor cortex; parietal lobe; stroke rehabilitation