title: The auditory steady state response: far-field recordings from the chinchilla.
abstract: OBJECTIVE
  Previous studies in our lab have found that the presentation of multiple ASSR-generating stimuli results in a decrease in ASSR amplitude when recorded from an electrode implanted in the chinchilla inferior colliculus. The purpose of the present experiment was to determine whether this same effect occurs in far-field recordings, i.e. recordings similar to those made in human subjects. The effect of inhalant anesthesia on ASSR amplitude in response to multiple stimuli was also investigated.
  
  
  METHODS
  Stimuli consisted of three sinusoidally-amplitude modulated tones with carrier/modulation frequencies of (1/.095 kHz), (2/.1 kHz), or (4/.107 kHz). The modulated carriers were presented to the right ear either alone or in combination, while recordings were made from subdermal needle electrodes placed on the head.
  
  
  METHODS
  Nine adult chinchillas.
  
  
  RESULTS
  A 20%-70% decrease in the response amplitude with the presentation of multiple ASSR-generating stimuli was found, which depended on both carrier frequency as well as stimulus pairing. In general, both the ASSR and the noise floor were reduced under anesthesia.
  
  
  CONCLUSIONS
  The time savings obtained from presenting multiple stimuli simultaneously may not be as great as initially predicted, as the time saving is at least partially offset by the observed amplitude reduction.
authors.affiliation: Department of Rehabilitation Science, University at Buffalo, NY 14214, USA. kmszalda@buffalo.edu
authors.forename: Kathleen M
authors.initials: KM
authors.lastname: McNerney
authors.forename: Robert F
authors.initials: RF
authors.lastname: Burkard
mesh_terms: D000758:Anesthesia; D018685:Anesthetics, Inhalation; D000818:Animals; D001299:Audiometry / Q000379:methods*; D001309:Auditory Threshold; D002682:Chinchilla; D007530:Isoflurane
chemical_list: D018685:Anesthetics, Inhalation; D007530:Isoflurane