Intensity coding of auditory stimuli: an fMRI study

Author(s): Shah, N. J., Posse, S., GrosseRyuken, M., MullerGartner, H. W.

Journal/Book: Neuropsychologia. 1998; 36: The Boulevard, Langford Lane, Kidlington, Oxford OX5 1GB, England. Pergamon-Elsevier Science Ltd. 875-883.

Abstract: The effect of stimulus intensity (sound pressure level, SPL) of auditory stimuli on the BOLD response in the auditory cortex was investigated in 14 young and healthy subjects, with no hearing abnormalities, using echo-planar, functional magnetic resonance imaging (fMRI) during a verbal and a non-verbal auditory discrimination task. The stimuli were presented block-wise at three different intensities: 95, 85 and 75 dB (SPL). All subjects showed fMRI signal increases in superior temporal gyrus (STG) covering primary and secondary auditory cortex. Most importantly, the spatial extent of the fMRI response in STG increased with increasing stimulus intensity. It is hypothesized that spreading of excitation is associated with the encoding of increasing stimulus intensity levels. In addition, we found bifrontal activation supposedly evoked by the auditory-articulary loop of working memory. The results presented here should assist in the design of optimal activation strategies for studying the auditory cortex with fMRI paradigms and may help in understanding intensity coding of auditory stimuli.

Note: Article Jancke L, Otto Von Guericke Univ, Inst Gen Psychol, Lennestr 6, D-39016 Magdeburg, GERMANY

Keyword(s): cerebral blood flow; auditory cortex; functional imaging; acoustic perception; temporal lobe; magnetic resonance imaging; functional magnetic resonance imaging; FUNCTIONAL MR; CORTEX; BRAIN; ACTIVATION; SPEECH

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