title: Scalp- and sLORETA-derived loudness dependence of auditory evoked potentials (LDAEPs) in unmedicated depressed males and females and healthy controls.
abstract: OBJECTIVE
  As major depressive disorder (MDD) is associated with altered 5-HT activity, we probed intensity-dependent auditory evoked potentials (AEPs) and loudness dependence of the AEP (LDAEP) slopes, shown pre-clinically to be inversely related to 5-HT activity, in MDD.
  
  
  METHODS
  AEPs and LDAEP slopes were measured in MDD (N=50; 27 females) and controls (N=43; 23 females). Correlations between scalp AEPs/LDAEPs and low-resolution electromagnetic tomography (sLORETA)-derived indices were assessed.
  
  
  RESULTS
  Smaller scalp intensity-dependent N1 and N1/P2 amplitudes in MDD versus control males and longer P2 latencies in MDD versus control females were found; no LDAEP group differences existed. Females had greater scalp AEPs, steeper N1 and N1/P2 scalp LDAEPs as well as greater intensity-dependent primary auditory cortex activation during the N1 than males. Scalp LDAEPs correlated weak-moderately with sLORETA counterparts. P2 LDAEP-sLORETA correlated negatively with MADRS scores. Female P2 and N1/P2 LDAEP-sLORETA correlated negatively with HAMD-17 and MADRS scores.
  
  
  CONCLUSIONS
  MDD was not associated with altered LDAEPs. Impaired processing or potentiated inhibition of auditory stimuli was found in MDD males; longer processing existed in MDD females. Inverse relationships between LDAEPs and clinical scores may be related to treatment history, personality and/or MDD features.
  
  
  CONCLUSIONS
  MDD was not associated with an altered LDAEP, though subtle AEPs alterations were noted in MDD.
authors.affiliation: University of Ottawa Institute of Mental Health Research, Ottawa, ON, Canada. Natalia.Jaworska@rohcg.on.ca
authors.forename: Natalia
authors.initials: N
authors.lastname: Jaworska
authors.forename: Pierre
authors.initials: P
authors.lastname: Blier
authors.forename: Wendy
authors.initials: W
authors.lastname: Fusee
authors.forename: Verner
authors.initials: V
authors.lastname: Knott
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D000704:Analysis of Variance; D001931:Brain Mapping; D003863:Depression / Q000503:physiopathology*; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D008144:Loudness Perception / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D011569:Psychiatric Status Rating Scales; D011571:Psychoacoustics; D011930:Reaction Time / Q000502:physiology; D012727:Sex Characteristics; D013223:Statistics as Topic