Language
perception comprises mechanisms of
perception and discrimination of auditory stimuli. An important component of auditory
perception and discrimination concerns auditory objects. Many interesting auditory objects in our environment are of relatively long duration; however, the
temporal window of integration of
auditory cortex neurons processing these objects is very limited. Thus, it is necessary to make active use of
short-term memory in order to construct and temporarily store long-duration objects. We sought to understand the mechanisms by which
the brain manipulates long-duration tonal patterns, temporarily stores the segments of those patterns, and integrates them into an auditory object. We extended a previously constructed model of auditory recognition of short-duration tonal patterns by expanding the
prefrontal cortically-based
short-term memory module of the previous model into a
memory buffer with multiple
short-term memory submodules and by adding a gating module. The gating module distributes the segments of the input pattern to separate locations of the extended
prefrontal cortex in an orderly fashion, allowing a subsequent comparison of the stored segments against the segments of a second pattern. In addition to simulating behavioral data and electrical activity of
neurons, our model also produces simulations of the
blood oxygen level dependent (BOLD) signal as obtained in
fMRI studies. The results of these simulations provided us with predictions that we tested in an
fMRI experiment with normal volunteers. This
fMRI experiment used the same task and similar stimuli to that of the model. We compared simulated data with experimental values. We found that two
brain areas, the right
precentral gyrus and the left medial frontal
gyrus,
correlated well with our simulations of the
memory gating module. Other
fMRI studies of auditory
perception and discrimination have also found
correlation of
fMRI activation of those areas with similar tasks and thus provide further support to our findings.
