title: Frequency changes in a continuous tone: auditory cortical potentials.
abstract: OBJECTIVE
  We examined auditory cortical potentials in normal hearing subjects to spectral changes in continuous low and high frequency pure tones.
  
  
  METHODS
  Cortical potentials were recorded to increments of frequency from continuous 250 or 4000Hz tones. The magnitude of change was random and varied from 0% to 50% above the base frequency.
  
  
  RESULTS
  Potentials consisted of N100, P200 and a slow negative wave (SN). N100 amplitude, latency and dipole magnitude with frequency increments were significantly greater for low compared to high frequencies. Dipole amplitudes were greater in the right than left hemisphere for both base frequencies. The SN amplitude to frequency changes between 4% and 50% was not significantly related to the magnitude of spectral change.
  
  
  CONCLUSIONS
  Modulation of N100 amplitude and latency elicited by spectral change is more pronounced with low compared to high frequencies.
  
  
  CONCLUSIONS
  These data provide electrophysiological evidence that central processing of spectral changes in the cortex differs for low and high frequencies. Some of these differences may be related to both temporal- and spectral-based coding at the auditory periphery. Central representation of frequency change may be related to the different temporal windows of integration across frequencies.
authors.affiliation: Department of Neurology, University of California, 150 Med Surge 1, Irvine, CA 92697, USA. adimitri@uci.edu
authors.forename: Andrew
authors.initials: A
authors.lastname: Dimitrijevic
authors.forename: Henry J
authors.initials: HJ
authors.lastname: Michalewski
authors.forename: Fan-Gang
authors.initials: FG
authors.lastname: Zeng
authors.forename: Hillel
authors.initials: H
authors.lastname: Pratt
authors.forename: Arnold
authors.initials: A
authors.lastname: Starr
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D000704:Analysis of Variance; D001303:Auditory Cortex / Q000502:physiology*; D001307:Auditory Perception / Q000502:physiology*; D001309:Auditory Threshold / Q000502:physiology*; D001931:Brain Mapping; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D011601:Psychophysics; D011930:Reaction Time / Q000502:physiology