| |
Abstract:
Goals: To compare the cortical activation patterns associated
with working memory for auditorally-presented non-words vs. pure
tone stimuli. Methods: BOLD FMR imaging was performed on 12
right-handed, English-speaking adult subjects. Contiguous 5 mm
axial images were collected while they performed an "n-back"
working memory task. The stimuli employed were either monosyllabic
pseudowords conforming to the phonological rules of English, or
pure tone stimuli of 700 msec duration. Image data were analyzed
with SPM'96, using combined peak intensity and spatial extent
thresholds. Results: For both pure tone and non-word stimuli,
activation was found in prefrontal (Brodmann area 46), frontal
(Area 44) and temporal-parietal (Area 40) regions. For the pure
tone task, the Area 40 activation was slightly more anterior and
inferior (i.e., closer to primary auditory regions) than for the
nonword task. Conclusion: The brain regions activated for working
memory of pure tone vs. nonword stimuli are substantially similar
to each other, and similar to those reported with visual
presentation of real-word stimuli. The posterior cortical regions
that are engaged in this task show evidence of possible
hierarchical organization, with phonologically more complex stimuli
engaging brain regions that are more distant from primary auditory
cortices.
|
