Project: Research project

Project Details


Middle latency auditory evoked potential (MAEPs, latencies 10-70 msec)
provide a direct measure of the electrical activity associated with the
short-latency thalamic and cortical analysis of sounds in humans. However,
despite increasing clinical use little is known about their most
fundamental properties. For example, the cortical and subcortical
structures involved in MAEP generation remain in dispute, and it is
uncertain how they are organized: do they have tonotopic and/or spatiotopic
organizations like auditory structures in many species? We will address these basic issues in five experiments. Two new techniques
will be incorporated in all studies. First, we will record detailed scalp
topographies from 32 electrodes and extract Laplacean MAEPs (LAP-MAEPs)
over temporal sites. LAP-MAEPs enhance the resolution of MAEPs to focal
generators in auditory cortex. Second, we will correlate MAEP distributions
with the relative orientations of candidate MAEP generators measured
directly from high-resolution MRI scans. We will use these improved
techniques to study the organization of MAEP generators for processing the
intensity (Experiment I), frequency (Experiment II), and spatial position
(Experiment III) of auditory signals. Hypotheses about MAEP generators will be further tested in two experiments
that take advantage of our well-delineated clinical populations. In
Experiment IV, we will record MAEPs in patient groups with focal lesions of
candidate MAEP generators, including the superior temporal plane and
auditory cortex, dorsolateral frontal cortex, inferior parietal lobe, the
posterior thalamus and basal ganglia. In Experiment V, we will compare
MAEPs from the scalp and cortical surface in patient undergoing
craniotomies. The experiments in normal subjects and patients form a
comprehensive sequence that will provide a better understanding of the
shortlatency analysis of sounds in the human brain, and enhance the
clinical utility of MAEPs in neurological and neurosurgical applications.
Effective start/end date7/1/906/30/94


  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health


  • Medicine(all)
  • Neuroscience(all)


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