ABR topographic mapping with digital filtering using fast Fourier transform.
The power spectrum of normal ABR consists of three major parts: low (0-350 Hz: component A), middle (350-700 Hz: component B) and high (700-1200 Hz: component C) frequency components. With digital filtering using fast Fourier transform (FFT), three component waveforms of ABR were obtained and designated as component A, B and C. Component A has a positive peak which corresponds to wave V or the slow component of the original ABR. Component B has three positive peaks (B1-B3) which correspond to wave I, III and V, and component C has five positive peaks (C1-C5) which correspond to wave I-V. These three component waveforms of ABR were analyzed topographically in normal hearing adults and cats. In addition, changes in the topography of three component waveforms of ABR were studied in a series of experimentally induced lesions in the brainstem auditory pathway in cats. The following results were obtained: i) The highest voltage (HV) area of component B1 was detected on the ipsilateral side in normal adults and cats. The HV areas of component C1, C2 and C3 in normal adults and C1, C2 in normal cats were detected on the ipsilateral side. ii) There was a correlation between changes in component C and the lesion site of the auditory pathway. Component C appears to be the most sensitive indicator of the lesion site of the brainstem.
Suzuki
T
T
Department of Otolaryngology, Yamagata University School of Medicine, Japan.
Aoyagi
M
M
Koike
Y
Y
D000161:Acoustic Stimulation; D000328:Adult; D000818:Animals; D001306:Auditory Pathways / Q000502:physiology / Q000503:physiopathology; D001927:Brain Diseases / Q000503:physiopathology; D001931:Brain Mapping; D001933:Brain Stem / Q000502:physiology* / Q000503:physiopathology; D002415:Cats; D017626:Cochlear Nucleus / Q000503:physiopathology; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology*; D005583:Fourier Analysis; D006309:Hearing / Q000502:physiology; D006801:Humans; D007245:Inferior Colliculi / Q000503:physiopathology; D009847:Olivary Nucleus / Q000503:physiopathology; D011930:Reaction Time / Q000502:physiology; D012815:Signal Processing, Computer-Assisted