Showing papers on "Latency (engineering) published in 1983"

P300 Latency Correlates with Digit Span

Abstract: P300 latency from a simple auditory discrimination counting task was obtained along with a digit span memory task for a large group of neurologically normal subjects. Moderate significant negative correlations between the peak latency of the P3a and P3b subcomponents and total memory score were found, although no relationship was observed for other waveform component latencies and memory score. The data suggest that the P300 component of the event-related brain potential may index individual variations in memory ability.

Saccadic Latency Measurements in Dementia

Abstract: • We measured saccadic latencies in patients with Alzheimer's dementia (AD) and other types of dementia. The saccadic latencies for both groups were considerably longer than those for age-matched controls. The prolongation was as extensive in patients with other types of dementia as it was in those with AD. There was no correlation between latency and the severity of the dementia.

Short latency somatosensory evoked potential in children

Abstract: The short latency somatosensory evoked potential was studied in 90 normal children of 1 month to 16 years old and 7 adults. Somatosensory stimuli were delivered through a disc electrode placed over the median nerve at the wrist joint. The uniform recording sites used were the central region of the scalp, and the seventh cervical spine or Erb's point. Reference electrodes were placed on the hand contralateral to the median nerve stimulated. Three positive peaks (P 1 , P 2 and P 3 ) and one negative peak (N 1 ) were consistently recorded, a further positive peak (P 4 after N 1 was not always observed. The latency of each peak per 1 m body length decreased with age until 2 or 5 years of age. The latency of each peak after 2 years of age was positively correlated with the body length and arm length. The value of P 1 peak latency per 1 m body length reaches adult values at an earlier rate than the value of P 3 peak latency and P 2 –P 3 latency per 1 m body length. This suggests that central lemmiscal pathways mature at a slower rate than peripheral nerve fibers. The wave form pattern of the short latency somatosensory evoked potential changed to the adult pattern at 10 years of age. The peak latency of P 4 during deep sleep was slightly prolonged. In recording on infants during sleep, the EEG should be monitored to determine the stage of sleep.

Theinvestigation oftraumatic lesions ofthebrachial plexus byelectromyography andshort latency somatosensory potentials evoked bystimulation of multiple peripheral nerves

Abstract: A study of 10 patients with brachial plexus trauma was performed to determine whether the diagnostic accuracy of sensory evoked potentials (SEPs) may be improved by using stimulation of multiple peripheral nerves (median, radial, musculocutaneous and ulnar). In addition, the relative advantages of SEPs and peripheral electrophysiological studies were considered. SEP patterns following most common brachial plexus lesions were predictable. Injuries to the upper trunk affected the musculocutaneous and radial SEPs predominantly. Lower trunk or medial cord lesions primarily affected ulnar SEPs. Diffuse brachial plexus lesions affected SEPs from all stimulation sites. In the majority of cases, the necessary information was obtainable from conventional EMG: however, for lesions involving the upper segments only, SEP techniques were more useful. It is suggested that selective SEPs from appropriate peripheral nerves when interpreted in combination with conventional EMG may add useful additional information.

Correlation of activity in neighbouring goldfish ganglion cells: relationship between latency and lag.

Abstract: Pairs of retinal ganglion cells in the isolated goldfish retina were recorded simultaneously with a single electrode. Repeated flashes of light were delivered to evaluate the response latency of each of the units. The cross-correlation histogram for the maintained discharge of each pair of cells was examined, and its temporal relationships (lags) were compared with the differences in response latencies of the two units. There was a strong correlation between these measures; however, the differences between latencies were often at least twice as great as the lags. The differences between the times to the peaks of the responses of the two units were less reliably related to the lags of the pairs, although the correlation was positive and the differences in time-to-peak generally greater than the lags. The weaker relationship between the difference in time-to-peak and lag than between latency difference and lag is apparently a manifestation of a negative correlation between latency and rise time (from first response to peak). This indicates that cells with a longer latency compensate with a faster rise time. There was a negative correlation between the mean maintained rate of a neurone and its response latency. That is, cells with faster maintained discharge rates respond sooner than those with slower maintained rates. There was virtually no relationship between the lags or the differences in latency and the differences between the magnitudes of the responses to light. Thus, it is unlikely that differences in latency (or lags) could be attributed to unequal effectiveness of the stimuli for the two units. The relationship between differences in latency and lags did not depend on the response categorizations of the two units. Specifically, it did not matter whether the members of the pair were on centre, off centre or on-off centre; neither did it matter whether they were X-like or not-X-like neurones. Consideration of these data leads to the conclusion that there must be 'marked' pathways of differential conduction velocity through the retina.

Luminance Effects on Latency and Topography of Average Pattern-Evoked Potentials

Abstract: With decreasing target luminance (0 to 2.0 log unit density filters), the latency of the checkerboard reversal-evoked scalp potential component P1 increased non-linearly in a population of 17 healthy volunteers. It is suggested that the non-linear latency increase in the evoked potential reflects the gradual increase of rod activity at the lower luminance level.

Diagnostic value of auditory brain stem responses (ABR) in differential diagnosis between cochlear deafness and acoustic neuromas.

Abstract: The diagnostic value of ABR for the differential diagnosis between cochlear deafness (CD) and acoustic neuromas (AN) was investigated. The following ABR parameters against 80 dB click stimulation was compared between CD and AN; (1) incidence of presence of each wave, (2) wave I latency, (3) wave III latency, (4) wave V latency, (5) I-III interpeak latency, (6) I-V interpeak latency, (7) right and left latency difference of wave III, (8) right and left latency difference of wave V, and (9) ABR pattern. It was concluded that a battery of 6 latency parameters (3-8) is very useful for the differential diagnosis between CD and AN and therefore it can be expected to be used as a powerful tool for finding out the small size AN.

Temporal Aspects of Eye Movement When Viewing Multiple Targets.

Abstract: : A technique of eye position measurement and analysis was used to investigate the time necessary for processing visual information by comparing the mean response latency time of single targets to the response means of other novel stimuli. In all cases, stimuli were visual, context-free, point source targets, randomized for type, order of appearance, and time course. The separation of the visual fields is exploited to selectively present targets to either or both hemispheres. An asymmetry in single target left-right response latency time was observed in nearly all subjects. In all cases, there was a significant increase in response latency time when targets were presented to each hemisphere simultaneously. Delayed bihemispheric stimulation produced changes in response latency that were similar in both directions and the response latency increased still further when targets were presented sequentially. These studies helped to determine the timing of events prior to the execution of a saccade. The single and bihemispheric paradigms have also proven useful in studying the mechanisms and organization of visual information processing. (Author)

Comparison of results of auditory brain stem response and acoustic reflex latency in acoustic tumor diagnosis.

Abstract: Persons with cerebellopontine angle tumors often have an increase in the latency of the acoustic reflex response that is comparable to the auditory brain stem response (ABR) in its sensitivity. However, reflex latency is less specific, since it may be prolonged in patients with Meniere's disease.

A simulation program with latency exploitation for the transient analysis of digital circuits

Abstract: : This report examines the efficiency that can be obtained in the simulation of large digital integrated circuits with the implementation of latency, that is, inactive gates in a given time interval are bypassed in the simulation. In particular the latency criterion in the program SLATE is studied, and a user's guide to SLATE is included. (Author)

Time course of suppression of spontaneous otoacoustic emissions

Abstract: Few data are available on the time course of suppression, by externally introduced sounds, of spontaneous otoacoustic emissions (SOAEs), and none have been presented for humans. By means of extensive averaging in the time domain and digital filtering, we have obtained such data for the (synchronized) SOAE produced by the first author's right ear (7529 Hz, 10–16 dB SPL). Upon presentation of a tone pip, there is a latency (1.2 ms at high suppressor levels, longer at lower levels) before any change can be detected in SOAE level. Most of the suppression then develops over an interval lasting 1.5–2.0 ms, but this relatively fast onset is followed by a roughly exponential slope with a time constant longer than 4 ms. At low suppressor levels, the latency to the beginning of recovery from suppression may be similar to the latency to suppression onset; for higher suppressor levels, the latency may be several tens of ms and recovery may not be complete before 100 ms. Given the uncertainty that still exists on trav...