title: Determination of the loudness dependence of auditory evoked potentials: single-electrode estimation versus dipole source analysis.
abstract: OBJECTIVE
  The loudness dependence of auditory evoked potentials (LDAEP) has been described as a measure of central serotonergic activity. Single-electrode estimation and dipole source analysis (DSA) are the most utilized methods for the estimation of LDAEP. To date, it is assumed that both methods are equally reliable. Nevertheless, according to our knowledge, the advantage of either method has not yet been shown directly. The aim of our study was to compare single-electrode estimation and dipole source analysis in the determination of the LDAEP.
  
  
  METHODS
  Tones of five different intensities were presented binaurally to 10 healthy volunteers. Amplitudes of N1/P2 and LDAEP were determined at the central electrode site referenced to average and to linked mastoids and with DSA in the left and the right hemispheres. Scores were normalized (z-scores), compared, and correlated.
  
  
  RESULTS
  Contrary to our expectations, we found a significant difference between scores obtained with single-electrode estimation and with DSA.
  
  
  CONCLUSIONS
  The difference may be caused by confounding activation of a frontal source in the single-electrode method. The single-electrode approach cannot be equated with DSA in the determination of the LDAEP. This should be considered when comparing the results of different LDAEP studies using only one of these methods.
authors: Work Group Clinical Neurophysiology, Research Group Clinical and Experimental Psychopathology, Department of Social and General Psychiatry, Psychiatric University Hospital Zurich and University of Zurich, Zurich, Switzerland.
authors: Florence
authors: F
authors: Hagenmuller
authors: Konrad
authors: K
authors: Hitz
authors: Felix
authors: F
authors: Darvas
authors: Wolfram
authors: W
authors: Kawohl
mesh_terms: D000161:Acoustic Stimulation / Q000295:instrumentation* / Q000379:methods* / Q000706:statistics & numerical data; D000328:Adult; D001303:Auditory Cortex / Q000502:physiology*; D004566:Electrodes; D004569:Electroencephalography / Q000379:methods / Q000706:statistics & numerical data; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D008144:Loudness Perception / Q000502:physiology*; D008297:Male