title: Refractory effects of the N1 event-related potential in experienced cochlear implant patients.
abstract: OBJECTIVE
  To determine if cochlear implant (CI) patients exhibit a temporal processing deficit for auditory stimuli, by examining refractory effects of the N1 event-related potential (ERP) component.
  
  
  METHODS
  CI patients and normally-hearing controls were tested in an auditory refractory period paradigm while ERP recordings were collected across the scalp. Participants were presented with brief 500-Hz tones that were separated by inter-stimulus intervals (ISIs) of 500, 1000, or 3000 ms. The amplitude of the N1 was examined as a function of ISI within each group.
  
  
  METHODS
  Ten adult CI patients and 13 age-matched normally-hearing controls were tested. Patients had long-lasting severe or profound sensorineural hearing loss prior to implantation, and a minimum of two years experience with CI activation.
  
  
  RESULTS
  Unlike normally-hearing controls, CI users showed no refractory effect for tones at 500 ms ISIs compared to 1000 ms. However, similar to controls, recovery from refractoriness was observed in anterior locations at 3000 ms.
  
  
  CONCLUSIONS
  The refractory period threshold, defined as the minimum ISI where different N1 amplitudes are elicited, is greater than 1000 ms in CI patients; at least double that of normally-hearing controls.
authors.affiliation: Department of Psychology and Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Cowper-Smith
authors.forename: Janet
authors.initials: J
authors.lastname: Green
authors.forename: Heather
authors.initials: H
authors.lastname: Maessen
authors.forename: Manohar
authors.initials: M
authors.lastname: Bance
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Newman
mesh_terms: D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D001299:Audiometry; D001303:Auditory Cortex / Q000503:physiopathology*; D016022:Case-Control Studies; D019929:Cochlear Implantation / Q000295:instrumentation*; D003054:Cochlear Implants; D012048:Correction of Hearing Impairment; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory; D005260:Female; D006319:Hearing Loss, Sensorineural / Q000503:physiopathology / Q000523:psychology / Q000534:rehabilitation*; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D019986:Persons with Hearing Disabilities / Q000534:rehabilitation*; D011571:Psychoacoustics; D011930:Reaction Time; D012032:Refractory Period, Electrophysiological; D012815:Signal Processing, Computer-Assisted; D013997:Time Factors; D055815:Young Adult