Accession Number : ADA138407

Title :   The Application of a Superconducting Quantum Interference Device Second-Order Gradiometer to Measure Visual Evoked Responses.

Descriptive Note : Master's thesis,


Personal Author(s) : Murray,R D

PDF Url : ADA138407

Report Date : Dec 1983

Pagination or Media Count : 171

Abstract : The acquisition of a Superconducting Quantum Interference Device (SQUID) gradiometer, along with the previous research which led to the first cortical implant of a multiplexed multi-electrode semiconductor brain electrode, motivated the use of the SQUID second-order gradiometer to measure visual evoked responses (VER) from humans, and from the canine which had previously had the AFIT brain electrode implanted and removed. Some discussion of the current dipole model for the fields measured from the brain is presented. The human visual evoked responses picked up by gradiometer were compared to previous human electroencephalograph visual evoked responses, and were found to have similar latencies. The canine visual evoked responses which were measured by the gradiometer had similar initial waveform and latencies, but then dampen out more rapidly than the waveforms measured by the AFIT brain chip. Conclusions about the use of a SQUID gradiometer in measuring visual evoked responses, along with comparisons between the EEG and AFIT brain chip data versus the SQUID data is discussed.

Descriptors :   *Magnetoencephalograms, *Gradiometers, *Visual perception, Electrodes, Surgical implantation, Cerebral cortex, Response(Biology), Biomagnetism, Interference, Josephson junctions, Superconductors, Magnetic dipoles, Theory, Magnetic fields, Multiplexing, Electroencephalography, Comparison, Mathematical prediction, Waveforms, Dogs, Humans, Brain, Diagnosis(Medicine), Theses

Subject Categories : Anatomy and Physiology
      Electrical and Electronic Equipment
      Magnetic & Electric Fld Detection & Detectors

Distribution Statement : APPROVED FOR PUBLIC RELEASE