Purpose: Our goal was to determine the distribution of auditory and language cortex activation in response to acoustic echo planar scanner noise with functional MRI (fMRI). Method: Acoustic scanner noise and spoken text, reproduced on high output cassette tape, were separately delivered at equivalent intensifies to six normal hearing adult volunteers through earphones during fMRI data acquisition. In nine other subjects, taped scanner noise was delivered in five successive iterations of the task to assess the consistency of conical activation to the noise stimulus. Gyri of the auditory and language system were divided into l0 different subregions for analysis of conical activation. The number of activated pixels and proportion of volunteers activating each conical subregion were determined using a cross- correlation analysis. Results: Conical activation to taped acoustic scanner noise was present within the transverse temporal gyms (primary auditory cortex) in all subjects, but activation was highly variable between subjects in auditory association and language relevant cortex. Auditory association cortex activation was seen in the planum polari, planum temporali, and middle temporal gyrus/superior temporal sulcus regions in one-half to twothirds of the volunteers. There was no significant difference in the distribution of conical activation within individual subjects across five successive iterations of the scanner noise task. Listening to spoken text consistently activated primary and association auditory cortex bilaterally as well as language relevant cortex in some cases. The mean number of activated pixels was significantly greater for text listening than acoustic scanner noise in auditory association and language relevant cortical subregions (p < 0.01), although the distribution of activity was similar between the two tasks. Conclusion: This preliminary investigation suggests that the complex sounds produced by the echo planar pulse sequence can activate relatively large regions of auditory and language cortex bilaterally, with the extent of activation outside the primary auditory cortex being variable between subjects. However, the distribution of activation within individual subjects was relatively constant across several iterations of the scanner noise stimulus.
All Science Journal Classification (ASJC) codes
- Radiology Nuclear Medicine and imaging
- Brain, metabolism
- Magnetic resonance imaging, functional