Abstract:

Few studies have examined brain activity in response to auditory stimuli using functional magnetic resonance imaging (fMRI) due to the inherent loudness of the scanner noise. Here, the scanner noise has been incorporated into the design of a speech recognition in noise task. Normal-hearing subjects were scanned on a Picker EDGE 1.5-T MR scanner; structural and functional images were acquired for 15 coronal slices. In one active task, sentences included contextual information so that the final words were highly predictable from the other words in the sentence (PH); in the other active task, sentences had no contextual information so that the same final words were not predictable (PL). Using nonmetallic noise-reduction earphones, sentences were presented to subjects' right ears for 1-min blocks, alternating with 1-min blocks with no speech stimuli. Using a multiple subtraction technique, activation during rest was subtracted from activation in response to both low-context sentences (PL-rest) and high-context sentences (PH-rest). The difference between activation in response to low-context and high-context sentences was also determined (PL--PH). This analysis identifies areas of brain activation associated with processing acoustic/phonetic information within words with and without sentence context. [Work supported by NIH/NIDCD.]