Persistence and integration: Two consequences of a sliding integrator

The present research used a startle amplitude reduction paradigm to investigate the ability of the rat's auditory system to track rapidly changing acoustic transients. Specifically examined was the ability of brief gaps in otherwise continuous noise to reduce the amplitude of a subsequently elicited acoustic startle reflex. The duration of the gap, time between gap offset and startle elicitation (the interstimulus interval or lSI), and rise-fall characteristics of the gap were systematically varied. Consistent with previous research, gaps reliably reduced startle amplitude. Gaps 2 msec long were reliably detected, and a 50-msec lSI resulted in the greatest amplitude reduction. Gaps presented at short ISIs produced amplitude reduction that followed a different time course than did gaps presented at longer ISIs. These results may reflect differences in the length of time available for the processing of the stimulus and may involve two different processes.

Section: Discussionsupporting

confidence: 81%

Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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Parameters affecting gap detection in the rat

Leitner

Hammond

Springer

et al. 1993

“…These results suggest that the temporal interval needed for one to hear two auditory signals as distinctly separate is a linear decreasing function of signal duration. Similarly, Penner (1975) found that for marker durations ranging from I to 10 msec, detection of an empty interval improved with decreasing marker duration; with marker durations ranging from 30 to 200 msec, however, detection of empty intervals was no longer affected.…”

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confidence: 96%

Temporal discrimination as a function of marker duration

Rammsayer¹,

Leutner

1996

In a series of three experiments, the effect of marker duration on temporal discrimination was evaluated with empty auditory intervals bounded by markers ranging from 3 to 300 msec or presented as a gap within a continuous tone. As a measure of performance, difference thresholds in relation to a base duration of 50 msec were computed. Performance on temporal discrimination was significantly better with markers ranging from 3 to 150msec than with markers ranging from 225 to 300 msec or under the gap condition. However, within each range of marker duration (3-150 msec; 225-300 msec or gap) performance did not differ significantly. A fourth experiment provided evidence that the effect of marker duration cannot be explained in terms of marker-induced masking. Agood approximation of the relationship between marker duration and temporal discrimination performance in the present experiments is a smooth step function, which can account for 99.3% of the variance of mean discrimination performance. Thus, the findings of the present study point to the conclusion that two different mechanisms are used in the processing of temporal information, depending on the duration of the auditory markers. The tradeoff point for the hypothetical shift from one timing mechanism to the other may be found at a marker duration of approximately 200 msec.Because the auditory system has the finest temporal resolution of all the senses, auditory stimuli have been used in many studies on the processing of temporal information. Two types of stimuli can be applied in timing experiments: the filled interval, and the empty interval. In filled auditory intervals, a tone or noise burst is presented continuously throughout the interval, whereas in empty intervals, only the onset and the offset of the interval are marked. In empty intervals, no auditory stimulus is presented during the interval itself, and differences in stimulus characteristics of empty intervals are therefore limited to features of the markers used. The purpose of the following series of experiments was to investigate the effects of marker duration on the timing of brief empty auditory intervals.With empty intervals, a conditio sine qua non for the perception of duration is that the onset and the offset markers be perceived as two distinct events: an interval has to appear to be between the two markers for the duration of the interval to be judged. In order to be perceived as two events, the markers must be separated by a minimal time interval, referred to as the auditory fusion

“…Moreover, Kellogg, Ison, and Miller (1983) reported that prenatal diazepam exposure in rats retarded the development of auditory temporal resolution, as indexed by the effectiveness of acoustic gaps as startle inhibitors. It is of special interest that Ison and Pinckney (1983) reported that the minimum gap required to reliably produce inhibition of an elicited eyeblink in humans (again approximately 4 msec) corresponds to the values reported in various assessments of the threshold for gap detection, as measured with standard psychophysical procedures (Penner, 1975;Perrott & Williams, 1971;Plomp, 1964;Smiarowski & Carhart, 1976;Williams, Elfner, & Howse, 1979).…”

Section: Tonal Frequency Shifts and Gaps In Acoustic Stimulation As Rmentioning

confidence: 99%

Tonal frequency shifts and gaps in acoustic stimulation as reflex-modifying events

Cranney

Hoffman

Cohen

1984

When a relatively weak signal, such as a mild tone, precedes an intense reflex-eliciting stimulus by an appropriate interval (about 100 msec), the amplitude of the elicited reaction is often reduced. It was found that in student volunteers a brief gap in a steady pure tone that occurred 150 msec prior to a mild tap to the glabella (the flat region between the eyebrows) could inhibit the eyeblink elicited by the tap. It was also found that a shift in tonal frequency across a gap in a tone was more inhibitory than a gap with no frequency shift, but it was no more inhibitory than the onset of the short second tone alone. The final study determined the minimum amount of frequency shift required to produce an additional inhibitory effect above that of a gap alone. The findings are discussed in terms of various aspects of sensory processing.