title: Auditory discrimination after left-hemisphere stroke: a mismatch negativity follow-up study.
abstract: OBJECTIVE
  We sought to determine the recovery of cortical auditory discrimination in aphasic, left-hemisphere-stroke patients by using an electrophysiological response called mismatch negativity (MMN) and speech-comprehension tests.
  
  
  METHODS
  MMN in 8 left-hemisphere stroke patients was recorded in response to duration and frequency changes in a repetitive, harmonically rich tone 4 and 10 days and again 3 and 6 months after their first unilateral stroke. Eight age-matched, healthy persons served as control subjects.
  
  
  RESULTS
  At 4 days after stroke onset, patients' sound discrimination was impaired in their left hemisphere, as suggested by attenuated MMNs, especially to right-ear stimuli. At 3 months after stroke, however, MMN to the right-ear duration change had significantly increased and was of normal size. A significant change for the frequency MMN was found for left-ear stimuli between 3 and 6 months after stroke. During the follow-up period, progressive improvement in speech-comprehension tests was also observed. Furthermore, there was a significant correlation between the change in the duration MMN amplitude and the Boston Diagnostic Aphasia Examination speech-comprehension test from 10 days to 3 months after stroke.
  
  
  CONCLUSIONS
  These results suggest that the MMN can be used as an index of the recovery of auditory discrimination.
authors.affiliation: Cognitive Brain Research Unit, Department of Psychology, University of Helsinki, Finland.
authors.forename: Titta-Maria
authors.initials: TM
authors.lastname: Ilvonen
authors.forename: Teija
authors.initials: T
authors.lastname: Kujala
authors.forename: Anita
authors.initials: A
authors.lastname: Kiesiläinen
authors.forename: Oili
authors.initials: O
authors.lastname: Salonen
authors.forename: Hesham
authors.initials: H
authors.lastname: Kozou
authors.forename: Eero
authors.initials: E
authors.lastname: Pekkonen
authors.forename: Risto O
authors.initials: RO
authors.lastname: Roine
authors.forename: Markku
authors.initials: M
authors.lastname: Kaste
authors.forename: Risto
authors.initials: R
authors.lastname: Näätänen
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D001037:Aphasia / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*; D004594:Electrophysiology; D005071:Evoked Potentials; D005260:Female; D005500:Follow-Up Studies; D007839:Functional Laterality; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011930:Reaction Time; D020127:Recovery of Function; D012016:Reference Values; D013063:Speech Discrimination Tests / Q000379:methods; D020521:Stroke / Q000150:complications / Q000503:physiopathology*; D014057:Tomography, X-Ray Computed