title: [Application of simultaneous auditory evoked potentials and functional magnetic resonance recordings for examination of central auditory system--preliminary results].
abstract: BACKGROUND
  Processing of auditory information in central nervous system bases on the series of quickly occurring neural processes that cannot be separately monitored using only the fMRI registration. Simultaneous recording of the auditory evoked potentials, characterized by good temporal resolution, and the functional magnetic resonance imaging with excellent spatial resolution allows studying higher auditory functions with precision both in time and space.
  
  
  OBJECTIVE
  was to implement the simultaneous AEP-fMRI recordings method for the investigation of information processing at different levels of central auditory system.
  
  
  METHODS
  Five healthy volunteers, aged 22-35 years, participated in the experiment. The study was performed using high-field (3T) MR scanner from Siemens and 64-channel electrophysiological system Neuroscan from Compumedics. Auditory evoked potentials generated by acoustic stimuli (standard and deviant tones) were registered using modified odd-ball procedure. Functional magnetic resonance recordings were performed using sparse acquisition paradigm. The results of electrophysiological registrations have been worked out by determining voltage distributions of AEP on skull and modeling their bioelectrical intracerebral generators (dipoles). FMRI activations were determined on the basis of deviant to standard and standard to deviant functional contrasts. Results obtained from electrophysiological studies have been integrated with functional outcomes.
  
  
  RESULTS
  Morphology, amplitude, latency and voltage distribution of auditory evoked potentials (P1, N1, P2) to standard stimuli presented during simultaneous AEP-fMRI registrations were very similar to the responses obtained outside scanner room. Significant fMRI activations to standard stimuli were found mainly in the auditory cortex. Activations in these regions corresponded with N1 wave dipoles modeled based on auditory potentials generated by standard tones. Auditory evoked potentials to deviant stimuli were recorded only outside the MRI scanner. However, deviant stimuli induced significant fMRI activations. They were observed mainly in the anterior cingulate gyrus, insula and parietal lobes. These regions of the brain are related to attention and decision-making processes.
  
  
  CONCLUSIONS
  The results showed that applied paradigm is suitable for investigation of acoustic processing on the level of auditory cortex. Technique of the simultaneous AEP-fMRI registrations seems to be promising for investigation of more complex nervous processes in central auditory system with good temporo-spatial resolution.
authors.affiliation: Zakład Epidemiologii i Badań Przesiewowych Instytutu Fizjologii i Patologii Słuchu w Warszawie. r.milner@ifps.org.pl
authors.forename: Rafał
authors.initials: R
authors.lastname: Milner
authors.forename: Mateusz
authors.initials: M
authors.lastname: Rusiniak
authors.forename: Tomasz
authors.initials: T
authors.lastname: Wolak
authors.forename: Ewa
authors.initials: E
authors.lastname: Piatkowska-Janko
authors.forename: Patrycja
authors.initials: P
authors.lastname: Naumczyk
authors.forename: Piotr
authors.initials: P
authors.lastname: Bogorodzki
authors.forename: Andrzej
authors.initials: A
authors.lastname: Senderski
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Ganc
authors.forename: Henryk
authors.initials: H
authors.lastname: Skarzyński
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods*; D000328:Adult; D001303:Auditory Cortex / Q000502:physiology*; D001307:Auditory Perception / Q000502:physiology*; D001931:Brain Mapping / Q000295:instrumentation*; D002490:Central Nervous System / Q000502:physiology*; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006309:Hearing / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D012016:Reference Values; D055815:Young Adult