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Biomedical subjects

J I Aunon

Publications and source records attributed to J I Aunon.

15 recordsLinked to original sources
PubMed1990

A new mode of communication between man and his surroundings.

The material presented in this paper is the result of a research project that was designed to study the feasibility of establishing an alternative mode of communication between man and his surroundings. The new form of communication proposed uses only the subject's brain waves with no overt physical action required. Subjects' electroencephalograms (EEG) were recorded while they performed various mental tasks designed to elicit hemispheric responses. Features formed from the EEG recording were then used as inputs into a Bayes quadratic classifier to test classification accuracy between the various tasks. The results obtained indicate that it is possible to accurately distinguish between any pair of the five tasks investigated. A comparison between three different methods for creating the feature sets is also presented.

Adult↗
PubMed1990

On intersensory evoked potentials.

It has been found in a variety of studies that, for human observers, reaction time is faster to a sound than to a light. The study being reported here was designed to test the hypothesis of audio-visual facilitation when a flash precedes a sound by about 30 to 50 milliseconds. It is hypothesized that the electrophysiological result of this facilitation will be an increased energy of the event related potential (ERP) resulting from the interaction between the visual and auditory processes. The stimuli consisted of a click (A), a flash (V), a simultaneous flash-click (AV), a flash preceding the click by 40 milliseconds (AV40) and by 80 milliseconds (AV 80). All of the stimuli were presented to the subject at random. Comparison of the ERP averages for the five subjects tested, and for the above mentioned conditions, supported the hypothesis of sensory integration. The AV40 averages indicated a larger recruitment of cells, as evidenced by a larger response than the AV, A, or V responses separately.

Adaptation, Physiological↗
PubMed1978

Computer techniques for the processing of evoked potentials.

A computer technique is described for the systematic characterization of brain evoked potentials. Preprocessing of the data by a causal digital filter is followed by a peak search and identification procedure. A latency histogram of the peaks found is constructed to determine the ranges or clusters of peaks within the single evoked potential. Peaks found within the clusters are then corrected to the mean latency of the cluster and a latency corrected average version of the evoked potential constructed.

Adult↗
PubMed1977

VEP and AEP variability: interlaboratory vs. intralaboratory and intersession vs. intrasession variability.

The VEP and AEP of a normal adult were recorded at single sessions in five laboratories that used different instrumentation. The results were compared with VEP and AEP data recorded at eight weekly testing sessions at one of the labs. The interlaboratory standard deviation was found to be over twice as large as the intralaboratory standard deviation measured over an eight week period. Intrasession EP variability was significantly less than intersession variability.

Adult↗
PubMed1977

High frequency components in the spectrum of the visual evoked potential.

The occurrence of short term high frequency components in the spectra of the VEP is usually overshadowed by larger amplitude slow waves which occur simultaneously with the high frequency waves. The high frequency components become evident when the time varying power spectra of short duration (250 ms) segments of the VEP are examined. Two types of short duration time varying power spectra are considered: one is obtained directly from overlapping time segments of the average VEP; and, the other is obtained by computing the spectra from the average autocorrelation functions of overlapping time segments of the data following each stimulus. The first yields the time varying properties for the spectra of the stimulus-synchronized data while, the latter shows the time varying properties of both the synchronized and unsynchronized data present.

Adult↗
PubMed1977

Effects of hypothermia on the visual-evoked brain potential in dogs.

Visual-evoked potentials, as seen on a signal-averaged electroencephalogram, demonstrated clearly recognizable changes in 6 normal dogs undergoing deep hypothermia and rewarming. These changes were more clearly recognizable than changes in the unevoked electroencephalogram with or without signal averaging.

Animals↗