title: The effect of 1/f fluctuation in inter-stimulus intervals on auditory evoked mismatch field.
abstract: This study focused on the effect of regularity of environmental stimuli on the informational order extracting function of human brain. The regularity of environmental stimuli can be described with the exponent n of the fluctuation 1/f(n). We studied the effect of the exponent of the fluctuation in the inter-stimulus interval (ISI) on the elicitation of auditory evoked mismatch fields (MMF) with two sounds with alternating frequency. ISI times were given by three types of fluctuation, 1/f(0), 1/f(1), 1/f(2), and with a fixed interval (1/f(infinity)). The root mean square (RMS) value of the MMF increased significantly (F(3/9)=4.95, p=0.027) with increases in the exponent of the fluctuation. Increments in the regularity of the fluctuation provoked enhancement of the MMF, which reflected the production of a memory trace, based on the anticipation of the stimulus timing. The gradient of the curve, indicating the ratio of increments between the MMF and the exponent of fluctuation, can express a subject's capability to extract regularity from fluctuating stimuli.
authors.affiliation: Institute for Human Science and Biomedical Engineering, Kansai Research Center, National Institute of Advanced Industrial Science (AIST), OSL-Building, 1-8-31 Midoriga-Oka, Ikeda, Osaka 563-8577, Japan. n-harada@aist.go.jp
authors.forename: Nobuyoshi
authors.initials: N
authors.lastname: Harada
authors.forename: Tadashi
authors.initials: T
authors.lastname: Masuda
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Endo
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Tsunehiro
authors.initials: T
authors.lastname: Takeda
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Tonoike
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D001303:Auditory Cortex / Q000502:physiology*; D001307:Auditory Perception / Q000502:physiology*; D004569:Electroencephalography / Q000379:methods; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D015225:Magnetoencephalography / Q000379:methods; D008297:Male; D011930:Reaction Time / Q000502:physiology; D013997:Time Factors