Biomedical subjects

M I Mendel

Publications and source records attributed to M I Mendel.

4 recordsLinked to original sources

PubMed1977

Influence of succinylcholine on middle component auditory evoked potentials.

Auditory evoked potentials in the middle component time domain (post-stimulus, 8 to 50 msec) were recorded in response to 1,000-Hz tone pips in a normal-hearing adult subject. Electromyographic (EMG) responses in response to ulnar nerve shocks were recorded from the ipsilateral hypothenar muscles. With the assistance of an anesthesiologist, data were collected during a normal resting state, a state of light sedation, and a state of complete skeletal muscle paralysis from succinylcholine administration. During the paralyzed state, there was abolition of the normal EMG responses seen in the resting and sedated states. The auditory evoked potentials, however, appeared unchanged during the paralyzed state, indicating that they were not of myogenic origin.

Acoustic Stimulation↗

PubMed1977

Effects of stimulus frequency and intensity on the middle componenets of the averaged auditory eletroencephalic response.

Middle components (latency 8-50 msec) of the averaged auditory electroencephalic response (AAER), evoked by brief duration tone bursts, were recorded from 11 normal-hearing subjects. Latency and amplitude measurements were made on five peaks (Na, Pa, Nb, Pb, and Nc) of the AAER waveforms recorded for 27 experimental conditions: three conditions of stimulus frequency (250, 1000, and 4000 Hz) at each of nine conditions of signal intensity (a no-stimulus control and 10, 20, 30, 40, 50, 60, 70, and 80 dB fe: group thresholds). Latency for each peak decreased with increased stimulus frequency, and it tended to decrease slightly with increases in stimulus intensity. Amplitude input-output characteristics varied with stimulus frequency and response peak. In general, the most linear input-output characteristics occurred for the early peaks and high stimulus frequencies. Characteristics for later peaks and lower frequencies tended to asymptote at moderate stimulus intensities. Between-subject variability was not much greater than within-subject variability for the single event auditory evoked potential (AEP). The variance of the AEP, however, was nearly as great (as much as two-thirds) as the variance of the background EEG, despite the large difference between AEP and background EEG amplitude.

Acoustic Stimulation↗

PubMed1975

Audiometric comparison of the middle and late components of the adult auditory evoked potentials awake and asleep.

The middle and the late components of auditory evoked potentials were alternately recorded in sequential sets from 28 adults, both awake and asleep. Sleep was induced by secobarbital and was monitored for depth. 1000 c/sec tone pips in one laboratory or filtered clicks in the other were delivered at 10, 20 or 30 dB sensation level. Control collections without stimulation were included. For the middle responses a single simple scoring template and one set of voltage criteria could be used for all stages of waking and sleeping. For late responses different templates and voltage criteria were needed. Estimates of the threshold of detection of the evoked potentials were based on the percentage of clearly positive responses was often not attained at 30 dB SL, i.e., the threshold was indeterminate. In light sleep and awake the middle responses of most subjects gave thresholds more sensitive than the late by 10-15 dB and also fewer indeterminate trials. The results in our two laboratories agreed closely in spite of differences in equipment and details of procedure. The relatively low thresholds of the middle responses (median 17.5 dB SL awake and 15 dB SL in light sleep) suggest that the middle responses must be considered seriously for use in clinical electric response audiometry, even though one of the 28 subjects failed to yield any identifiable middle responses.

Adult↗

PubMedDate not supplied

Middle components of the auditory evoked potentials in infants.

Middle components of the averaged auditory evoked potentials (AEP) were recorded from 18 infants, 6 each at one, four and eight months of age, during natural sleep, Tone bursts centered at 1000 Hz were presented from a loudspeaker at 15, 30, 45 and 60 dB HL (re: normal adult tone burst threshold). In addition, an equal duration no stimulus control AEP was also obtained. Each averaged response consisted of the sum of 400 stimuli presented at a rate of about 6/sec. Latencies and amplitudes of the three peaks, Na, Pa and Nb, were analyzed as a function of age and intensity. There were no significant differences in latency as a function of age, and only peak Pa showed a significant increase in amplitude as a function of increasing age. The latency of peak Pa decreased significantly as a function of intensity, while the amplitude of all three peaks showed significant differences as a function of intensity. Judges' scores of the presence of responses showed that at 60 dB HL, all infants yielded patterns which were scored as "response present." Smaller percentages of "response present" were scored for the successively lower intensity levels. The results from the 18 infants in this study were similar to those obtained from six normal, sleeping adults tested under identical stimulating and recording conditions in this laboratory.

Acoustic Stimulation↗