title: Relationship between transient and steady-state pattern electroretinograms: theoretical and experimental assessment.
abstract: OBJECTIVE
  We determined if the overlap of transient (tr) pattern electroretinograms (PERG(tr)) can explain the generation of the steady-state (SS) pattern electroretinogram (PERG(SS)), and investigated the relationship between the two types of responses.
  
  
  METHODS
  Slightly jittered pattern reversals were used to generate quasi SS (QSS) PERG(SS) responses from eight normal subjects, recorded using lower eyelid skin electrodes, at rates between 6.9 and 26.5 reversals per second (rps). Jittered quasi PERG(SS) were deconvolved using the frequency domain continuous loop averaging deconvolution method. Additionally, conventional PERG(tr) at 2.2 rps and PERG(SS) at each of the QSS stimulation rates were obtained from all subjects. Two synthetic PERG(SS) responses were constructed at each stimulation rate, one using the PERG(tr) obtained at that rate, and the other using the conventional 2.2 rps PERG(tr). Synthetic responses then were compared to the recorded PERG(SS) using amplitude, latency, and spectral measurements.
  
  
  RESULTS
  Findings indicate that the PERG(SS) obtained at SS rates can be predicted using the superposition of deconvolved tr PERGs at each particular rate. Although conventional PERG(tr) can explain PERG(SS) obtained at rates below 15.4 rps (≥ 97% correlation), for higher reversal rates only deconvolved responses obtained at that rate can produce the recorded SS responses (96% vs. 65% correlation at 26.5 rps).
  
  
  CONCLUSIONS
  The study shows that PERG(SS) results from the overlapping of tr PERG(tr) waveforms generated at that reversal rate. The first two peaks (N(SS) and P(SS)) of the PERG(SS) reflect N35 and P50 waves of the tr PERG(tr). The N95 amplitude is reduced at conventional (16 rps) SS rates, but contributes to the overall PERG(SS) amplitude.
authors.affiliation: University of Miami, Department of Biomedical Engineering, Coral Gables, Florida, United States University of Miami, Departments of Otolaryngology, Pediatrics, and Neuroscience (Graduate), Miami, Florida, United States.
authors.forename: Özcan
authors.initials: Ö
authors.lastname: Özdamar
authors.affiliation: University of Miami, Department of Biomedical Engineering, Coral Gables, Florida, United States.
authors.forename: Jonathon
authors.initials: J
authors.lastname: Toft-Nielsen
authors.affiliation: University of Miami, Department of Biomedical Engineering, Coral Gables, Florida, United States.
authors.forename: Jorge
authors.initials: J
authors.lastname: Bohórquez
authors.affiliation: University of Miami, Department of Biomedical Engineering, Coral Gables, Florida, United States University of Miami, Bascom Palmer Eye Institute, Miami, Florida, United States.
authors.forename: Vittorio
authors.initials: V
authors.lastname: Porciatti
mesh_terms: D004596:Electroretinography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D011930:Reaction Time / Q000502:physiology; D012165:Retinal Ganglion Cells / Q000502:physiology*; D055815:Young Adult
keywords: deconvolution; overlap; pattern electroretinogram; steady-state PERG; superposition; transient PERG