title: Are networks for residual language function and recovery consistent across aphasic patients?
abstract: OBJECTIVE
  If neuroplastic changes in aphasia are consistent across studies, this would imply relatively stereotyped mechanisms of recovery which could guide the design of more efficient noninvasive brain stimulation treatments. To address this question, we performed a meta-analysis of functional neuroimaging studies of chronic aphasia after stroke.
  
  
  METHODS
  Functional neuroimaging articles using language tasks in patients with chronic aphasia after stroke (n = 105) and control subjects (n = 129) were collected. Activation likelihood estimation meta-analysis determined areas of consistent activity in each group. Functional homology between areas recruited by aphasic patients and controls was assessed by determining whether they activated under the same experimental conditions.
  
  
  RESULTS
  Controls consistently activated a network of left hemisphere language areas. Aphasic patients consistently activated some spared left hemisphere language nodes, new left hemisphere areas, and right hemisphere areas homotopic to the control subjects' language network. Patients with left inferior frontal lesions recruited right inferior frontal gyrus more reliably than those without. Some areas, including right dorsal pars opercularis, were functionally homologous with corresponding control areas, while others, including right pars triangularis, were not.
  
  
  CONCLUSIONS
  The network of brain areas aphasic patients recruit for language functions is largely consistent across studies. Several recruitment mechanisms occur, including persistent function in spared nodes, compensatory recruitment of alternate nodes, and recruitment of areas that may hinder recovery. These findings may guide development of brain stimulation protocols that can be applied across populations of aphasic patients who share common attributes.
authors.affiliation: Laboratory for Cognition and Neural Stimulation, Department of Neurology, University of Pennsylvania Health System, 3400 Spruce Street, 3W Gates Building, Philadelphia, PA 19104, USA. peter.turkeltaub@uphs.upenn.edu
authors.forename: Peter E
authors.initials: PE
authors.lastname: Turkeltaub
authors.forename: Samuel
authors.initials: S
authors.lastname: Messing
authors.forename: Catherine
authors.initials: C
authors.lastname: Norise
authors.forename: Roy H
authors.initials: RH
authors.lastname: Hamilton
mesh_terms: D001037:Aphasia / Q000000981:diagnostic imaging / Q000473:pathology*; D002540:Cerebral Cortex / Q000000981:diagnostic imaging / Q000473:pathology; D002908:Chronic Disease; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007802:Language; D016013:Likelihood Functions; D008279:Magnetic Resonance Imaging; D009415:Nerve Net / Q000000981:diagnostic imaging / Q000473:pathology*; D009473:Neuronal Plasticity / Q000502:physiology; D049268:Positron-Emission Tomography; D011597:Psychomotor Performance / Q000502:physiology; D020127:Recovery of Function; D020521:Stroke / Q000473:pathology