Michael G. Saunders

Amplitude probability density studies on alpha and alpha-like patterns

Abstract The amplitude probability density functions of various synthetic waveforms and normal alpha activity have been determined using digital computer techniques. The amplitude probability densities of alpha activity in the subjects tested were Gaussian and the envelope amplitude probaility ability densities showed a Rayleigh form. These findings suggest that alpha activity may have analogous characteristics to noise after passage through a narrow-band filter.

Determination of peripheral sensory nerve conduction velocities in man from stimulus response delays of the cortical evoked potentials

Abstract Techniques of using the somatosensory responses of the brain as indicators of sensory nerve stimulation and their application to measurement of peripheral sensory nerve conduction velocities in forty normal subjects are described. It appears that use of both the computer averaged evoked response and the smoothed first derivative of this permit estimates of the conduction velocity to be made. Sources of error in estimations are discussed. Values of sensory conduction velocities in the forty subjects are given for the left and right median, ulnar, anterior tibial and peroneal nerves.

An automatic device to convert electroencephalograph records into digital form

Abstract A device has been described which is capable of converting standard EEG records into digital or numerical form so that these figures may be operated on by electronic computers. The device scans up to eight channels of EEG records, measures the amplitude of the record at 0.5 mm intervals and presents the digital data in printed form as well as on computer tape. The accuracy and limitations of the device are described.

Measurement of effective input resistance of electroencephalograph amplifiers.

Abstract A method of determining the resistive load of the input of electroencephalograph amplifiers under working conditions has been described. It has been found that the effective resistance is considerably less than that of the value of the grid resistors.

The measurement of phase shift in electroencephalograph pen recorders

Abstract Two methods of determining the degree of phase shift or time lag in the pens of electroencephalograph recorders are described. Both methods demonstrate time lags in the range of 3.0 or 4.5 msec., depending on the types of two different machines examined. The time lags remain almost constant over the range of 2 to 50 c/sec. Some of the equipment used was provided through a grant from the National Research Council of Canada. The electroencephalographs used were in the departments of the Winnipeg General Hospital, the Manitoba Clinic and Deer Lodge Veterans Hospital.

Computers and medical research

Dr. Saunders emphasized the difference, between medical practice and medical research, in acceptance of computer usage.

A circuit to synchronise time marker, time base and stimulator

Abstract A circuit is described which permits synchronisation between a time marker and the time base and stimulator circuits. A frequency dividing circuit is also described which triggers the time base just before the stimulator is triggered.

Computers and medical practice

One of the interesting aspects of both sessions on Medicine was the familiarity of the medical people with computer usage. Camouflaging their titles, they could have infiltrated any group of programmers or data processing managers without detection. Dr. Saunders made it clear, however, that they are doctors first.