Auditory Evoked Magnetic Fields: A Replication with Comments on the Magnetic P50 Analog.
Abstract
Auditory evoked magnetic fields (AEFs) and EEG auditory evoked potentials (AEPs) were recorded from left and right auditory cortical regions of 12 normal adult subjects. The magnetic sensor was a figure-eight SQUID gradiometer with a 4 cm baseline oriented so as to be maximally sensitive to a current dipole oriented normal to the Sylvian fissure. Stimuli were 100 msec long 1 kHz tone pips with a modal interstimulus interval of 700 msec delivered at sound pressure levels of 40, 60, 80, and 100 dB. AEF amplitude was found to be related to stimulus intensity in a quadratic fashion, AEP amplitude in a linear fashion. AEFs were of larger amplitude in response to contralateral as compared to ipsilateral stimulation. AEPs did not exhibit such a relationship. In a second experiment right hemisphere AEFs and AEPs in response to contralateral ear stimulation tone in these 12 subjects were combined with similar previous data from 24 subjects, providing a total of 36 subjects, to examine the comparability of the AEP P50 waveform and the AEF P50 analog. The latency of the P50 was found to decrease as a function of increasing stimulus intensity for both AEFs and AEPs but the P50 latency was consistently shorter in magnetic compared to potential recordings.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 12, 1982
- Accession Number
- ADA121621
Entities
People
- J. E. Zimmerman.
- J. Edrich
- J. T. Zimmerman
- M. Reite
Organizations
- University of Colorado Boulder