Electrophysiological studies in humans and animals suggest that noninvasive neurostimulation methods such as transcranial direct current stimulation (tDCS) can elicit long-lasting [1Fritsch B. Reis J. Martinowich K. Schambra H.M. Ji Y. Cohen L.G. Lu B. Direct current stimulation promotes BDNF-dependent synaptic plasticity: Potential implications for motor learning.Neuron. 2010; 66: 198-204Abstract Full Text Full Text PDF PubMed Scopus (1047) Google Scholar], polarity-dependent [2Nitsche M.A. Paulus W. Excitability changes induced in the human motor cortex by weak transcranial direct current stimulation.J. Physiol. 2000; 527: 633-639Crossref PubMed Scopus (4052) Google Scholar] changes in neocortical excitability. Application of tDCS can have significant and selective behavioral consequences that are associated with the cortical location of the stimulation electrodes and the task engaged during stimulation [3de Vries M.H. Barth A.C.R. Maiworm S. Knecht S. Zwitserlood P. Flöel A. Electrical stimulation of Broca's area enhances implicit learning of an artificial grammar.J. Cogn. Neurosci. 2010; 22: 2427-2436Crossref PubMed Scopus (146) Google Scholar, 4Flöel A. Rösser N. Michka O. Knecht S. Breitenstein C. Noninvasive brain stimulation improves language learning.J. Cogn. Neurosci. 2008; 20: 1415-1422Crossref PubMed Scopus (336) Google Scholar, 5Sparing R. Dafotakis M. Meister I.G. Thirugnanasambandam N. Fink G.R. Enhancing language performance with non-invasive brain stimulation—a transcranial direct current stimulation study in healthy humans.Neuropsychologia. 2008; 46: 261-268Crossref PubMed Scopus (204) Google Scholar, 6Baker J.M. Rorden C. Fridriksson J. Using transcranial direct-current stimulation to treat stroke patients with aphasia.Stroke. 2010; 41: 1229-1236Crossref PubMed Scopus (429) Google Scholar, 7Fertonani A. Rosini S. Cotelli M. Rossini P.M. Miniussi C. Naming facilitation induced by transcranial direct current stimulation.Behav. Brain Res. 2010; 208: 311-318Crossref PubMed Scopus (232) Google Scholar, 8Fiori V. Coccia M. Marinelli C.V. Vecchi V. Bonifazi S. Ceravolo M.G. Provinciali L. Tomaiuolo F. Marangolo P. Transcranial direct current stimulation improves word retrieval in healthy and nonfluent aphasic subjects.J. Cogn. Neurosci. 2011; 23: 2309-2323Crossref PubMed Scopus (236) Google Scholar]. However, the mechanism by which tDCS affects human behavior is unclear. Recently, functional magnetic resonance imaging (fMRI) has been used to determine the spatial topography of tDCS effects [9Stagg C.J. O'Shea J. Kincses Z.T. Woolrich M. Matthews P.M. Johansen-Berg H. Modulation of movement-associated cortical activation by transcranial direct current stimulation.Eur. J. Neurosci. 2009; 30: 1412-1423Crossref PubMed Scopus (141) Google Scholar, 10Kwon Y.H. Ko M.H. Ahn S.H. Kim Y.H. Song J.C. Lee C.H. Chang M.C. Jang S.H. Primary motor cortex activation by transcranial direct current stimulation in the human brain.Neurosci. Lett. 2008; 435: 56-59Crossref PubMed Scopus (121) Google Scholar, 11Kwon Y.H. Jang S.H. The enhanced cortical activation induced by transcranial direct current stimulation during hand movements.Neurosci. Lett. 2011; 492: 105-108Crossref PubMed Scopus (43) Google Scholar, 12Antal A. Polania R. Schmidt-Samoa C. Dechent P. Paulus W. Transcranial direct current stimulation over the primary motor cortex during fMRI.Neuroimage. 2011; 55: 590-596Crossref PubMed Scopus (205) Google Scholar, 13Polanía R. Paulus W. Antal A. Nitsche M.A. Introducing graph theory to track for neuroplastic alterations in the resting human brain: A transcranial direct current stimulation study.Neuroimage. 2011; 54: 2287-2296Crossref PubMed Scopus (207) Google Scholar], but no behavioral data were collected during stimulation. The present study is unique in this regard, in that both neural and behavioral responses were recorded using a novel combination of left frontal anodal tDCS during an overt picture-naming fMRI study. We found that tDCS had significant behavioral and regionally specific neural facilitation effects. Furthermore, faster naming responses correlated with decreased blood oxygen level-dependent (BOLD) signal in Broca's area. Our data support the importance of Broca's area within the normal naming network and as such indicate that Broca's area may be a suitable candidate site for tDCS in neurorehabilitation of anomic patients, whose brain damage spares this region.
Anti-HMGCR (3-hydroxy-3-methylglutaryl coenzyme A reductase) myopathy is an immune-mediated necrotising myopathy. Atypical presentations hinder its recognition and its prompt treatment. We present two patients with atypical clinical or pathological features. A 45-year-old woman had an asymptomatic serum creatine kinase (CK) of ~10 000 IU/L and muscle biopsy showing minimal changes. She then developed slowly progressive proximal weakness, diagnosed as limb-girdle muscular dystrophy but with negative genetics. Twelve years later, now with severe proximal weakness, her MR scan of muscle showed diffuse asymmetrical fatty degeneration, with conspicuous hyperintense STIR signal abnormalities. HMGCR antibodies were positive and she partially improved with immunosuppression. The second patient developed slowly progressive proximal limb weakness with a high serum CK (~4000 IU/L); muscle biopsy showed a lymphocyte infiltrate with angiocentric distribution suggesting vasculitis. Serum HMGCR antibodies were positive. Anti-HMGCR myopathy can present as a slowly progressive myopathy with atypical pathology. HMGCR antibody screening is indicated for people with suspected limb-girdle muscular dystrophy or atypical inflammatory muscle conditions.
BACKGROUND: Neurorehabilitation technologies such as robot therapy (RT) and transcranial Direct Current Stimulation (tDCS) can promote upper limb (UL) motor recovery after stroke. OBJECTIVE: To explore the effect of anodal tDCS with uni-lateral and t
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