title: Broca's area damage is necessary but not sufficient to induce after-effects of cathodal tDCS on the unaffected hemisphere in post-stroke aphasia.
abstract: BACKGROUND
  The inter-individual variability of behavioral effects after tDCS applied to the unaffected right hemisphere in stroke may be related to factors such as the lesion location.
  
  
  OBJECTIVE
  We investigated the effect of left Broca's area (BA) damage on picture naming in aphasic patients after cathodal tDCS applied over the right BA.
  
  
  METHODS
  We conducted a study using pre-interventional diffusion and resting state functional MRI (rsfMRI) and two cross-over tDCS sessions (TYPE: sham and cathodal) over the right homologous BA in aphasic stroke patients with ischemic lesions involving the left BA (BA+) or other left brain areas (BA-). Picture naming accuracy was assessed after each session. Inter-hemispheric (IH) functional balance was investigated via rsfMRI connectivity maps using the right BA as a seed. Probabilistic tractography was used to study the integrity of language white matter pathways.
  
  
  RESULTS
  tDCS had different effects on picture naming accuracy in BA+ and BA- patients (TYPE × GROUP interaction, F(1,19): 4.6, P: 0.04). All BA- patients except one did not respond to tDCS and demonstrated normal IH balance between the right and left BA when compared to healthy subjects. BA+ patients were improved by tDCS in 36% and had decreased level of functional IH balance. Improvement in picture naming after cathodal tDCS was associated with the integrity of the arcuate fasciculus in BA+ patients.
  
  
  CONCLUSIONS
  Behavioral effects of cathodal tDCS on the unaffected right hemisphere differ depending on whether BA and the arcuate fasciculus are damaged. Therefore, IH imbalance could be a direct consequence of anatomical lesions.
authors.affiliation: CRICM - Centre de Recherche de l'Institut du Cerveau et de la Moelle épinière, UPMC Paris 6, Paris, France; Inserm, U975; CNRS, UMR 7225, Paris, France; COGIMAGE, UPMC Paris 6, Paris, France; APHP, Urgences Cérébro-Vasculaires, Hôpital Pitié-Salpêtrière, Paris, France; Univ Paris 11, IFR49, DSV/I2BM/NeuroSpin, Bat 145, Gif-sur-Yvette F-91191, France. Electronic address: charlotte.rosso@gmail.com.
authors.forename: C
authors.initials: C
authors.lastname: Rosso
authors.affiliation: Univ Paris 11, IFR49, DSV/I2BM/NeuroSpin, Bat 145, Gif-sur-Yvette F-91191, France; Inserm, UPMC Univ Paris 06, UMRS 678, Laboratoire d'Imagerie Fonctionnelle, Paris, France.
authors.forename: V
authors.initials: V
authors.lastname: Perlbarg
authors.affiliation: CRICM - Centre de Recherche de l'Institut du Cerveau et de la Moelle épinière, UPMC Paris 6, Paris, France; Inserm, U975; CNRS, UMR 7225, Paris, France; Institut du Cerveau et de la Moelle épinière, Centre de Neuro-Imagerie de Recherche (CENIR), Paris, France.
authors.forename: R
authors.initials: R
authors.lastname: Valabregue
authors.affiliation: APHP, Urgences Cérébro-Vasculaires, Hôpital Pitié-Salpêtrière, Paris, France; Centre des Maladies Cognitives et Comportementales, IM2A, Hôpital Pitié-Salpêtrière, Paris, France.
authors.forename: C
authors.initials: C
authors.lastname: Arbizu
authors.affiliation: Centre des Maladies Cognitives et Comportementales, IM2A, Hôpital Pitié-Salpêtrière, Paris, France; APHP, Service de Soins de suites et Réadaptation, Hôpital Pitié-Salpêtrière, Paris, France.
authors.forename: S
authors.initials: S
authors.lastname: Ferrieux
authors.affiliation: CRICM - Centre de Recherche de l'Institut du Cerveau et de la Moelle épinière, UPMC Paris 6, Paris, France; Inserm, U975; CNRS, UMR 7225, Paris, France; COGIMAGE, UPMC Paris 6, Paris, France.
authors.forename: B
authors.initials: B
authors.lastname: Alshawan
authors.affiliation: CRICM - Centre de Recherche de l'Institut du Cerveau et de la Moelle épinière, UPMC Paris 6, Paris, France; Inserm, U975; CNRS, UMR 7225, Paris, France; COGIMAGE, UPMC Paris 6, Paris, France.
authors.forename: P
authors.initials: P
authors.lastname: Vargas
authors.affiliation: APHP, Urgences Cérébro-Vasculaires, Hôpital Pitié-Salpêtrière, Paris, France.
authors.forename: A
authors.initials: A
authors.lastname: Leger
authors.affiliation: APHP, Service de Soins de suites et Réadaptation, Hôpital Pitié-Salpêtrière, Paris, France.
authors.forename: C
authors.initials: C
authors.lastname: Zavanone
authors.affiliation: CRICM - Centre de Recherche de l'Institut du Cerveau et de la Moelle épinière, UPMC Paris 6, Paris, France; Inserm, U975; CNRS, UMR 7225, Paris, France; INSERM, APHP, Centre d'Investigation Clinique CIC9503, Département des Maladies du Système Nerveux, Hôpital Pitié-Salpêtrière, Paris, France.
authors.forename: J C
authors.initials: JC
authors.lastname: Corvol
authors.affiliation: CRICM - Centre de Recherche de l'Institut du Cerveau et de la Moelle épinière, UPMC Paris 6, Paris, France; Inserm, U975; CNRS, UMR 7225, Paris, France; Institut du Cerveau et de la Moelle épinière, Movement Disorders and Basal Ganglia: Pathophysiology and Experimental Therapeutics, Paris, France.
authors.forename: S
authors.initials: S
authors.lastname: Meunier
authors.affiliation: CRICM - Centre de Recherche de l'Institut du Cerveau et de la Moelle épinière, UPMC Paris 6, Paris, France; Inserm, U975; CNRS, UMR 7225, Paris, France; Institut du Cerveau et de la Moelle épinière, Centre de Neuro-Imagerie de Recherche (CENIR), Paris, France; APHP, Service de Neuroradiologie, Hôpital Pitié-Salpêtrière, Paris, France.
authors.forename: S
authors.initials: S
authors.lastname: Lehéricy
authors.affiliation: CRICM - Centre de Recherche de l'Institut du Cerveau et de la Moelle épinière, UPMC Paris 6, Paris, France; Inserm, U975; CNRS, UMR 7225, Paris, France; COGIMAGE, UPMC Paris 6, Paris, France; APHP, Urgences Cérébro-Vasculaires, Hôpital Pitié-Salpêtrière, Paris, France.
authors.forename: Y
authors.initials: Y
authors.lastname: Samson
mesh_terms: D000328:Adult; D000368:Aged; D001039:Aphasia, Broca / Q000175:diagnosis* / Q000503:physiopathology / Q000628:therapy*; D001931:Brain Mapping / Q000379:methods; D065711:Broca Area / Q000473:pathology* / Q000503:physiopathology; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D010775:Photic Stimulation / Q000379:methods; D016037:Single-Blind Method; D020521:Stroke / Q000175:diagnosis* / Q000503:physiopathology / Q000628:therapy*; D065908:Transcranial Direct Current Stimulation / Q000379:methods*; D016896:Treatment Outcome
keywords: Diffusion tensor; Language; Resting state functional magnetic resonance imaging; Stroke; tDCS