Effects Of Stimulus Duration Research Articles

Activation of duration-sensitive auditory cortical fields in humans

The influence of stimulus duration on auditory evoked potentials (AEPs) was examined for tones varying randomly in duration, location, and frequency in an auditory selective attention task. Stimulus duration effects were isolated as duration difference waves by subtracting AEPs to short duration tones from AEPs to longer duration tones of identical location, frequency and rise time. This analysis revealed that AEP components generally increased in amplitude and decreased in latency with increments in signal duration, with evidence of longer temporal integration times for lower frequency tones. Different temporal integration functions were seen for different N1 subcomponents. The results suggest that different auditory cortical areas have different temporal integration times, and that these functions vary as a function of tone frequency.

The effect of stimulus duration on the latency of submaximal nerve volleys.

Muscle & NerveVolume 19, Issue 10 p. 1354-1356 Short Report The effect of stimulus duration on the latency of submaximal nerve volleys Ilona Mogyoros MD, Corresponding Author Ilona Mogyoros MD Prince of Wales Medical Research Institute and Department of Neurology, The Prince Henry and Prince of Wales Hospitals, Sydney, AustraliaPrince of Wales Medical Research Institute, High Street, Randwick, Sydney, N.S.W. 2031, AustraliaSearch for more papers by this authorMatthew C. Kiernan MB, BS, Matthew C. Kiernan MB, BS Prince of Wales Medical Research Institute and Department of Neurology, The Prince Henry and Prince of Wales Hospitals, Sydney, AustraliaSearch for more papers by this authorJean-Michel Gracies MD, PhD, Jean-Michel Gracies MD, PhD Prince of Wales Medical Research Institute and Department of Neurology, The Prince Henry and Prince of Wales Hospitals, Sydney, AustraliaSearch for more papers by this authorDavid Burke MD, DSc, David Burke MD, DSc Prince of Wales Medical Research Institute and Department of Neurology, The Prince Henry and Prince of Wales Hospitals, Sydney, AustraliaSearch for more papers by this author Ilona Mogyoros MD, Corresponding Author Ilona Mogyoros MD Prince of Wales Medical Research Institute and Department of Neurology, The Prince Henry and Prince of Wales Hospitals, Sydney, AustraliaPrince of Wales Medical Research Institute, High Street, Randwick, Sydney, N.S.W. 2031, AustraliaSearch for more papers by this authorMatthew C. Kiernan MB, BS, Matthew C. Kiernan MB, BS Prince of Wales Medical Research Institute and Department of Neurology, The Prince Henry and Prince of Wales Hospitals, Sydney, AustraliaSearch for more papers by this authorJean-Michel Gracies MD, PhD, Jean-Michel Gracies MD, PhD Prince of Wales Medical Research Institute and Department of Neurology, The Prince Henry and Prince of Wales Hospitals, Sydney, AustraliaSearch for more papers by this authorDavid Burke MD, DSc, David Burke MD, DSc Prince of Wales Medical Research Institute and Department of Neurology, The Prince Henry and Prince of Wales Hospitals, Sydney, AustraliaSearch for more papers by this author First published: October 1996 https://doi.org/10.1002/(SICI)1097-4598(199610)19:10<1354::AID-MUS18>3.0.CO;2-UCitations: 2AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article.Citing Literature Volume19, Issue10October 1996Pages 1354-1356 RelatedInformation

Effects of stimulus duration on the amplitude difference limen for vibrotaction.

Vibrotactile amplitude difference limens (DLs) were measured by the continuous pedestal and gated pedestal methods. In both cases, the relative DL decreased as a function of the intensity of the stimulus and the results, in most cases, could be described as a near miss to Weber's law. DLs measured by the continuous pedestal method were found to decrease substantially as a function of increases in stimulus duration over a range of 12 to 1000 ms. In contrast, DLs measured by the gated pedestal method were only slightly affected by changes in stimulus duration. It was concluded that the process of temporal summation can manifest itself in reducing the size of the DL in the continuous pedestal, but not the gated pedestal, paradigm.

A Computational Model of the Perceived Velocity of Moving Plaids

Local motion detection mechanisms generally lead to one component of the optic flow becoming indeterminate. One way to solve this ‘aperture problem’ is to compute the optic flow which minimises some smoothing constraint. With iterative schemes the computed velocity array is suboptimal relative to the constraint until the process has converged. Under the original assumption that the iteration rate is sufficiently low to allow the perception of suboptimal flows at short stimulus durations, iterative gradient models give an accurate description of biases in the perception of tilted line velocity. We examine whether this approach can be applied to moving sinusoidal plaids. Our simulations are in agreement with a number of psychophysical results on both speed and direction perception. In particular we show that the effect of stimulus duration on the perceived direction of type II plaids [Yo and Wilson, 1992 Vision Research32(1)] can be accounted for without recourse to second-order mechanisms. The effects of contrast and component directions on the evolution rate of this bias are well reproduced. The model also successfully describes the effect of spatial frequency, and data obtained with gratings. These results suggest that iterative gradient schemes can model the dynamics of interactions between local velocity detectors, as revealed by psychophysical experiments with lines and plaids.

Effects of Stimulus Duration, Temporal Delay, and Complexity on the Judgments of Dot Location

The present study investigated how information on location was processed at an early stage of information processing by the task of recognizing dots presented briefly and followed by a masking stimulus. 8 subjects were asked on 1528 trials to recognize the positions of dots presented on a circumference. Effects of number of dots (1, 2, and 3), duration of presentation (36, 56, 200, and 500 msec.), and time delay (interval between the offset of display and the onset of recognition stimulus, 100 and 500 msec.) were examined. Analyses showed that the percentage of correct recognition increased with the duration of presentation and that the effect of duration decreased with the number of dots. Meanwhile, no significant effect was found for time delay. Consequently, with increased duration, the information on location is transferred to short-term visual memory. However, the ratio of transfer from iconic storage to short-term visual memory with duration varied with the complexity of visual stimulus.

Physiological correlates of the time‐intensity trade in auditory late responses.

Numerous psychophysical studies have demonstrated that behavioral detection thresholds decrease with increasing stimulus duration, often referred to as the time‐intensity trade. Few studies, however, have evaluated the physiological correlates of this trading relationship. The purpose of the present study was to examine the effect of stimulus duration on evoked potential thresholds known as the auditory late response (ALR). Behavioral and ALR thresholds were estimated for 1000 and 4000 Hz tone bursts at 8, 16, 32, 64, and 128 ms in five normal‐hearing, young adults. Evoked responses were recorded in 2‐dB steps from 20 dB to −4 dB SL re: behavioral threshold. ALR threshold was estimated as the lowest level at which the N1‐P2 complex was visually detected by two independent judges. Preliminary results show that both behavioral and ALR thresholds decreased as a function of increasing duration. For the 1000‐Hz stimulus, both ALR and behavioral thresholds decreased by approximately 23 dB HL over the range of durations tested. Average ALR and behavioral thresholds for the 4000‐Hz stimulus decreased by about 19 dB HL. These results show that the time‐intensity trade can be demonstrated physiologically using the auditory late response.

Effects of stimulus duration and task experience on gaze shift.

The effects of stimulus duration and prior task experience on gaze shift were studied to determine the spatial characteristics of gaze shift as affected by prior experience. Thirty-six subjects (with normal or corrected-to-normal vision) participated in two sessions of a task that required viewing two consecutively presented letters at either 15 degrees or 50 degrees eccentricity and deciding whether they were the same or different. In the first session (SS1) a letter was presented for either 500 (N = 18) or 1000 ms (N = 18), followed by a second letter. In session 2 (SS2), the groups were divided with half of the group performing the task under the same conditions as they did in SS1, while the other half was switched to the other first letter duration. Head and eye movements were recorded using a photoelectric transducer and electrooculogram (EOG), respectively. Few head movements occurred with targets presented at 15 degrees eccentricity. Approximately 80% of gaze shifts to the 50 degrees stimuli included a head movement component. DURATION had a significant effect on gaze shift. Head movement amplitude (HMA) increased, while saccade amplitude decreased with an increase in DURATION. On the average, the proportion of gaze shift accomplished via head movement was 24% if DURATION was 500 ms, and 37% when DURATION was extended to 1000 ms. SS1 task experience affected HMA in SS2. When DURATIONs differed between SS1 and SS2, HMA in SS2 were drawn toward the level of HMA in SS1. A positive and significant correlation was observed between head movement amplitude and head movement duration. The results suggest that both stimulus availability and prior experience affect head movement amplitude in gaze shift.

The orienting response to brief auditory stimuli in preweanling and adult rats

The cardiac orienting response to brief auditory stimuli was measured in preweanling and adult rats. The eliciting stimulus varied in duration (2 or 10 s) and complexity (continuous or pulsing). Stimulus complexity affected response magnitude with the pulsing stimulus eliciting a larger response than the continuous stimulus. Stimulus duration affected response persistence but only when a pulsing stimulus was used. In contrast to recent research with stimuli of much longer duration, age did not significantly affect any aspect of the cardiac response to the novel auditory stimuli in the present study. These results are discussed in terms of (1) the effects of stimulus duration on the heart-rate component of the orienting response and (2) two-stage models of attention.

The effect of stimulus duration on frequency-response functions in the Pacinian (P) channel.

Psychophysical experiments on human observers and physiological measurements on Pacinian corpuscles (PCs) isolated from cat mesentery were performed to explain certain discrepancies in the psychophysical-physiological model (Bolanowski et al., 1988) for the sense of touch in the vibrotactle Pacinian (P) channel. The model was based on correlations among the psychophysical frequency response obtained on human glabrous skin and physiological frequency-response functions measured on two PC preparations: PC fibers innervating human glabrous skin (Johansson et al., 1982) and PCs isolated from cat mesentery. The three frequency-response functions were qualitatively similar. However, the low-frequency slope for the human PC fibers differed from the slopes for the psychophysical and cat mesentery PC functions by being 3 dB/octave less steep. This discrepancy can be explained theoretically by differences in methodology involving the effect of stimulus duration and the property of temporal summation known to exist in the P channel (i.e., a 3-dB increase in sensitivity per doubling of stimulus duration). To test this, experiments were performed using two methods of stimulation: (1) a constant stimulus duration for different test frequencies, as generally used in this laboratory; and (2) a constant number of stimulus cycles (n = 5) for each test frequency as used by Johansson et al. The method of least squares was used to calculate the low-frequency (50 to 150-Hz) slopes of individual psychophysical and physiological functions. The mean slopes that resulted from using the two methods of stimulation were consistent with the theoretical expectations.

Effect of stimulus duration on stapedius reflex threshold in electrical stimulation via cochlear implant.

The effect of stimulus duration on the threshold of the contralateral stapedius reflex was investigated in patients supplied with a Vienna cochlear implant (analog stimulation via CI) and compared to results of a normal-hearing reference group in case of acoustic stimulation. Changes in reflex threshold were determined at four frequencies (125, 500, 1,000 and 2,000 Hz in case of electrostimulation and at 500, 1,000, 2,000 and 4,000 Hz for acoustic stimulation) and for five durations (30, 50, 100, 300 and 500 ms). The comparison of the two stimulation modes was accomplished by using the same instrumentation and procedure. Reflex threshold was evaluated according to an objective criterion based on the individual noise distribution of recordings without reflex and by subjective judgement. For both stimulation modes a strong effect of stimulus duration on reflex threshold was observed (p < 0.001). The amount of temporal integration reflected by the threshold difference between 500 and 50 ms was approximately 2-4 dB for electrical stimulation via CI and 6 dB for acoustic stimulation in normal-hearing individuals. In case of electrostimulation, the reflex threshold for stimuli of 30 ms was most often above the limit of uncomfortable loudness sensation; the increase in reflex threshold for acoustic stimulation between 500 and 30 ms was approximately 14 dB. There was no evidence of frequency effect on reflex threshold nor an interaction between frequency and stimulus duration for either stimulation mode.

The contribution of waveform interactions to the perception of concurrent vowels.

Models of the auditory and phonetic analysis of speech must account for the ability of listeners to extract information from speech when competing voices are present. When two synthetic vowels are presented simultaneously and monaurally, listeners can exploit cues provided by a difference in fundamental frequency (F0) between the vowels to help determine their phonemic identities. Three experiments examined the effects of stimulus duration on the perception of such "double vowels." Experiment 1 confirmed earlier findings that a difference in F0 provides a smaller advantage when the duration of the stimulus is brief (50 ms rather than 200 ms). With brief stimuli, there may be insufficient time for attentional mechanisms to switch from the "dominant" member of the pair to the "nondominant" vowel. Alternatively, brief segments may restrict the availability of cues that are distributed over the time course of a longer segment of a double vowel. In experiment 1, listeners did not perform better when the same 50-ms segment was presented four times in succession (with 100-ms silent intervals) rather than only once, suggesting that limits on attention switching do not underlie the duration effect. However, performance improved in some conditions when four successive 50-ms segments were extracted from the 200-ms double vowels and presented in sequence, again with 100-ms silent intervals. Similar improvements were observed in experiment 2 between performance with the first 50-ms segment and one or more of the other three segments when the segments were presented individually. Experiment 3 demonstrated that part of the improvement observed in experiments 1 and 2 could be attributed to waveform interactions that either reinforce or attenuate harmonics that lie near vowel formants. Such interactions were beneficial only when the difference in F0 was small (0.25-1 semitone). These results are compatible with the idea that listeners benefit from small differences in F0 by performing a sequence of analyses of different time segments of a double vowel to determine where the formants of the constituent vowels are best defined.

Temporal properties of letter identification in retinitis pigmentosa

The effect of stimulus duration on the visual acuity of individuals with retinitis pigmentosa (RP) was assessed by using Sloan letters of 100% contrast and durations ranging from 15 ms to 3.8 s. In addition, contrast thresholds for identifying Sloan letters (0.7 log minimum angle of resolution; 20/100 Snellen equivalent) were measured over the same range of durations in the same subjects with RP. Compared with results from a control group of subjects with normal vision, the subjects with RP showed losses in visual acuity at all stimulus durations, with a slightly though significantly greater reduction in visual acuity at short durations. The letter-contrast thresholds of the subjects with RP were elevated above the normal range to the same degree at all durations. Analysis of the results in the format of letter contrast sensitivity functions indicates that temporal summation for letter identification was normal for these subjects with RP and that their relatively greater acuity loss at short exposure durations was most likely related to their elevated letter contrast thresholds.

Effects of phase duration on detection of electrical stimulation of the human cochlea

Detection thresholds for biphasic symmetric pulses were measured in fourteen human subjects implanted with the Cochlear Corporation Nucleus 22 Implant. The effects of phase duration on thresholds were studied using single pulses, and 500 ms pulse trains at 100 pps. Psychophysical detection thresholds decreased as a function of phase duration with a change in slope at approximately 0.5 ms/phase. Mean single-pulse and pulse-train slopes were −3.60 and −4.25 dB/doubling of phase duration for pulse durations of less than about 0.5 ms/phase. For pulse durations greater than 0.5 ms/phase, mean slopes were −5.71 and −7.54 dB/doubling for single pulses and pulse trains, respectively. Thresholds for pulse trains decreased as a function of stimulus duration for durations up to at least 300 ms, with the rate of decrease being dependent on the phase duration of the pulse. Effects of stimulus duration were greater for longer phase duration signals. We hypothesize that the longer phase duration pulses activate multiple spikes in a single fiber and/or more effective patterns of spikes across fibers, which may explain why slopes of psychophysical threshold functions are steeper than those of functions for single auditory nerve fibers for longer duration pulses. Thresholds were compared to respective speech perception scores (CID sentences) since thresholds for long phase duration signals have been shown previously to be correlated with nerve survival patterns, and nerve survival patterns may affect speech perception. Correlation coefficients ranged from −0.59 to −0.81, depending on stimulus parameters and subject selection.

Stimulus duration and the sensory memory trace: An event-related potential study

The mismatch negativity (MMN) of the auditory event-related potential is elicited when a stimulus deviates from that represented by the neural memory trace developed by preceding stimuli. The effect of stimulus duration on this trace was studied by presenting sequences of 1000 Hz, 80 dB stimuli to subjects engaged in silent reading. Stimuli were, in different blocks, either of 4, 10, 30, 100 or 300 ms in duration. 5% of the stimuli were deviants which were either higher in frequency (1050 Hz) or lower in intensity (70 dB) than the standards. The “silent” period between two successive stimuli was constant at 300 ms. The minimum stimulus duration with which a distinct MMN was elicited by frequency deviants was 30 ms, but the MMN amplitude was not increased when stimulus duration was further prolonged. In contrast, the intensity MMN was elicited even with stimulus duration of 10 ms and its amplitude increased as a function of stimulus duration. Reaction times and hit percentages in response to these deviant stimuli in a separate discrimination task displayed analogous patterns of results.

The effect of stimulus duration upon the components of fluctuation in static automated perimetry.

We studied the effect of varying the stimulus duration time on the components of fluctuation in static automated perimetry by testing 20 healthy subjects on the Humphrey Field Analyser within the central 20 degrees of vision. We found the total fluctuation at a stimulus duration of 0.065 s, to be 3.22 decibels (dB); 0.1 s, 3.22 dB; 0.2 s, 3.34 dB; 0.3 s, 2.95 dB; 0.4 s, 3.24 dB; and 0.5 s, 3.22 dB. Little difference was observed in the individual components (short-term, long-term homogeneous, long-term heterogeneous and inter-individual) or total fluctuation with an increasing stimulus presentation time when evaluated over the entire visual field or in a pointwise fashion. This study suggests that the stimulus duration within the range of times studied has little effect on the components or total fluctuation in healthy individuals.

Effects of stimulus duration on the response properties of Pacinian corpuscles: implications for the neural code.

Based on physiological and psychophysical data, it has been suggested that the neural code for threshold detection in the P channel, mediated by Pacinian corpuscles (PCs), may be 2-4 neural impulses/stimulus (Bolanowski et al., 1988). To further test the efficacy of this code, responses from PCs were measured at different vibratory burst durations. Since it is known that the P channel has the capacity to summate vibratory stimuli temporally within the central nervous system, the effect should also be present in the physiological results. Temporal summation predicts a decrease in threshold at a rate of -3 dB/doubling of stimulus duration. Responses from single PCs were integrated by counting neural spikes over the entire burst duration. Furthermore, real-time responses were integrated with a low-pass filter, more accurately modeling the central process. For the spike-counting scheme, a criterion of 4 impulses/stimulus showed a decrease in stimulus amplitude for increases in duration similar to that obtained psychophysically. The amplitude-duration function obtained with the low-pass filter, however, resulted in a function which did not follow that obtained psychophysically, regardless of the number of impulses/stimulus. Since the P channel is known to have a central integrator, it has been concluded that activity of a single PC afferent probably is not sufficient to signal threshold in the P channel.

The effect of stimulus duration using the Brookler-Grams closed-loop caloric irrigator.

Nystagmic responses to traditional 40-sec, 30 degrees C water calorics were recorded and compared to those obtained with the Brookler-Grams closed-loop irrigator using 30 degrees C, 40-, 50-, and 60-sec irrigations. Significant differences were noted between the responses to the water irrigator and the 40- and 50-sec closed-loop irrigations. The 60-sec closed-loop irrigation produced responses that were equivalent to the responses obtained with the water irrigation in slow component velocity, amplitude, frequency, latency, and duration. The 30 degrees C 60-sec closed-loop irrigation is an acceptable stimulus in electronystagmographic caloric testing.

The effect of stimulus duration on noxious-stimulus induced c- fos expression in the rodent spinal cord

C- fos is a proto-oncogene that is expressed within some neurons following depolarization. The protein product, fos, has been proposed as an anatomical marker for neuronal activity following noxious peripheral stimulation. However, the literature on noxious-stimulus induced fos expression contains several puzzling observations on the time course and laminar distribution of neuronal labeling within the spinal cord. This study has analyzed the effect of stimulus duration on the expression of fos-like immunoreactivity (FLI) within the spinal cord of anesthetized rats. In order to examine the time course of fos expression following brief periods of stimulation, we required a type of stimulus that was intense enough to activate nociceptors but that did not produce tissue damage. We have therefore employed pulsed, high intensity electrical stimulation, with stimulus durations ranging from 3 s to 24 h. The results indicate that stimulus duration has a profound effect upon the number of labeled cells, the intensity of neuronal labeling, the laminar pattern of FLI, and the time course of fos expression. Brief stimulation periods induce relatively few and relatively lightly labeled neurons, located predominantly within the most superficial laminae of the dorsal horn. Maximal immunoreactivity appears approximately 2 h after stimulation has ceased, and disappears within hours. Continuous stimulation produces many more labeled cells, darker labeling, and FLI within both dorsal and ventral laminar regions. Maximal FLI is seen after approximately 4.5 h of continuous stimulation, with reduction in the number of labeled cells thereafter. These data indicate that the results of any study employing c- fos as a marker for neuronal activity may be affected by the duration of the exciting stimulus.

Stimulus parameters and temporal evolution of the olfactory evoked potential in rats

Evoked potentials were recorded from olfactory bulb, piriform cortex and scalp in urethane anesthetized rats in response to brief odorant stimuli (amyl acetate, phenylethyl alcohol, eugenol) presented through a nasal cannula by means of a constant flow olfactometer. The effects of stimulus duration, nasal cannula position, flow rate, concentration and interstimulus interval were examined. The highest amplitude potentials were evoked by 10% amyl acetate at 20 ms duration, 1000 ml/min flow rate and a 60-s interstimulus interval with the stimulus delivered at the nares. Odorant evoked potentials from deep within the olfactory bulb consisted of a triphasic wave with major components at 60 ms (P60), 90 ms (N90) and 140 ms (P140) with the latter two reversing polarity close to the surface of the bulb. Potentials recorded from layer I of piriform cortex were of similar amplitude, but opposite in polarity to the deep olfactory bulb potentials. Recordings from the skin over the nose elicited waveforms of similar morphology to the deep olfactory bulb potentials, but one-quarter the amplitude and of opposite polarity The evoked potentials changed with repetitive stimulation The N90 component was not present initially and only appeared after several stimuli. The appearance of the N90 component depended on the integrity of the olfactory peduncle. Thus, olfactory evoked potentials to odorant stimuli reflect dynamic aspects of the encoding of olfactory information dependent on connections between olfactory bulb and piriform cortex

436 Human fetal response to vibroacoustic stimulation as a function of stimulus duration

The effect of stimulus duration on the initial fetal heart rate (FHR) acceleration response was evaluated by assessing its amplitude and span following a single vibroacoustic stimulation with durations of 0 (sham), 1, 3, or 5 seconds. Statistically significant differences were observed in the mean amplitude and duration of acceleration in groups 3 and 5 when compared with groups 0 and 1 (P less than .05). In addition, groups 3 and 5 demonstrated significantly greater fetal reactivity than group 0 and a decrease in testing time over groups 0 and 1 (P less than .05). Our results suggest that the magnitude of the FHR acceleration response is dependent on the duration of the stimulus. Furthermore, a 3-second sound stimulus appears to be adequate for a shift to the fetal behavioral "awake" state.