title: Olfactory speed - Temporal odor processing of paired stimuli.
abstract: OBJECTIVE
  Compared to other senses, temporal perception of odors seems fairly slow. In addition it has been shown in previous studies that even not consciously perceived odors could influence our behavior. Aim of the current study therefore was to study the interstimulus interval (ISI) length, which is necessary between two repetitive stimuli to be able to perceive them separately. The additional aim focused on observing central odor processing of not perceived odorous stimuli.
  
  
  METHODS
  The study was divided into three parts. In each part healthy, normosmic volunteers were included. In part I and II stimulus pairs (CO2, H2S, orange and phenyl ethyl alcohol (PEA)) were presented to the subjects via a computer-controlled olfactometer with short ISI of 0.6-9s. The decision whether one or two stimuli were perceived was recorded. In addition the influence of odor valence, trigeminallity and concentrations was observed. In part III olfactory event-related potentials (OERPs) to perceived and not-perceived odors were recorded.
  
  
  RESULTS
  The two stimuli of a stimulus pair were perceived separately more often with increasing ISI length. This increase was significant until an ISI between the stimuli of 4s. Odor intensity, pleasantness, trigeminallity and sex had no major influence on this. In addition we were able to observe that OERPs are less often detected in response to not perceived olfactory stimuli. However, the presence of OERP in response to not perceived stimuli in more than half of the cases indicated that even not perceived stimuli are centrally processed.
authors: Smell & Taste Clinic, Department of Otorhinolaryngology, University of Dresden Medical School, Dresden, Germany; Department of Neuropediatrics, University of Dresden Medical School, Dresden, Germany. Electronic address: valentin.schriever@mac.com.
authors: V A
authors: VA
authors: Schriever
authors: Smell & Taste Clinic, Department of Otorhinolaryngology, University of Dresden Medical School, Dresden, Germany. Electronic address: fcindy@web.de.
authors: C
authors: C
authors: Frenzel
authors: Smell & Taste Clinic, Department of Otorhinolaryngology, University of Dresden Medical School, Dresden, Germany. Electronic address: sandrawernecke@web.de.
authors: S
authors: S
authors: Wernecke
authors: Smell & Taste Clinic, Department of Otorhinolaryngology, University of Dresden Medical School, Dresden, Germany; Department of Clinical Neurophysiology, Sahlgrenska University Hospital, University of Gothenburg, Sweden. Electronic address: Ilona.Croy@neuro.gu.se.
authors: I
authors: I
authors: Croy
authors: Frey and Lau, Henstedt-Ulzburg, Germany. Electronic address: cvalder@freylau.de.
authors: C
authors: C
authors: Valder
authors: Smell & Taste Clinic, Department of Otorhinolaryngology, University of Dresden Medical School, Dresden, Germany. Electronic address: thummel@mail.zih.tu-dresden.de.
authors: T
authors: T
authors: Hummel
mesh_terms: D000328:Adult; D004305:Dose-Response Relationship, Drug; D004569:Electroencephalography; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009812:Odorants; D055696:Olfactory Perception / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology*; D012903:Smell / Q000502:physiology*; D013997:Time Factors; D055815:Young Adult
keywords: event-related potentials; odor perception; temporal