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T D Blumenthal

Publications and source records attributed to T D Blumenthal.

25 records · Page 2Linked to original sources
PubMed1989

Prepulse rise time and startle reflex modification: different effects for discrete and continuous prepulses.

The rise time of an auditory prepulse was varied to determine whether the onset transient of the prepulse is of primary importance in the modification of the acoustic startle reflex. In Experiment 1, 20-ms long discrete prepulses were presented at a lead time of 150 ms, and prepulse rise time was varied from 0.1 to 20 ms. Although all prepulses resulted in decreased response amplitude (inhibition of startle), varying rise time from 0.1 to 20 ms had no effect on reflex modification. These results suggest that the startle response is not sensitive to prepulse rise time changes in the range used here. In Experiment 2, continuous prepulses (in which lead time equals duration) were presented. Several of these prepulses had a lead time of 150 ms and rise times ranging from 0.1 to 150 ms, whereas others had a rise time of 0.1 ms and lead times of 50 to 150 ms. The results showed that only the fast-rising, 50-ms lead time prepulse decreased response amplitude, with the other prepulses having no effect on amplitude, relative to control responding. Rise time changes generally had no effect on responding, but responses were larger at longer lead times than at shorter lead times. Response probability was inhibited by fast-rising prepulses at lead times of 50 to 130 ms. Together with the results of Experiment 1, these findings suggest that startle reflex inhibition is determined by the onset of a prepulse, and that this inhibition is not sensitive to small changes in prepulse rise time.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

The startle response and auditory temporal summation in neonates.

The present study assessed temporal summation of transient and sustained stimuli in the startle eyeblink response system in neonates during quiet sleep. Subjects received 100-dB(A), fast-rising broadband noise bursts of two types: (a) single stimuli varying in duration from 20 to 100 ms and (b) pairs of 3-ms bursts presented at interpulse intervals corresponding to the single-stimulus durations. In addition, a single 3-ms pulse was used as an anchor point for both stimulus types. For startle amplitude, single stimuli were more effective than were paired stimuli, but the temporal summation functions were similar for the two types of stimuli. Response amplitude increased as stimulus duration/interval increased to 50 ms, but not beyond. For startle probability, temporal summation was similar for single and paired stimuli at 20 ms. Pairs of pulses were equally effective at 20, 35, and 50 ms, beyond which the second pulse was not effective. Increasing the duration of single stimuli from 20 to 35 ms resulted in increased probability, illustrating a contribution of sustained summation beyond that of transient summation. Response latency was generally greater for paired than for single stimuli. The results suggest that temporal summation of brief stimuli is deficient in the neonate. These data were compared to adult data from an analogous study, and suggest that the transient system is immature in infants, and that this immaturity is expressed differently by startle amplitude, probability, and latency.

Acoustic Stimulation↗
PubMedDate not supplied

Prepulses reduce the pain of cutaneous electrical shocks.

OBJECTIVE: Both the startle reflex elicited by an intense acoustic or tactile stimulus and the perceived intensity of that stimulus can be diminished by a weak "prepulse" that precedes the startling stimulus. The present study examined whether prepulses can also diminish the pain produced by an intense electrical stimulus similar to that used to treat life-threatening cardiac arrhythmias in conscious patients with implantable cardioverter/defibrillators or transcutaneous pacemakers. METHODS: Perceptual and pain thresholds for electrical shocks to the arm were determined in 20 adults. Participants then rated the painfulness of 25 electrical shocks that were 1.5 times the pain threshold (mean shock intensity, approximately 160 V) and either presented alone or preceded (at 40-60 ms) by weak electrical prepulses equal to or 25% above the perceptual threshold. RESULTS: Prepulses significantly reduced the pain produced by the intense shocks. Individuals with the lowest pain thresholds experienced the greatest pain reduction with prepulses. In these more sensitive individuals, the most effective prepulses reduced perceived pain by 26% across the entire test session and by 54% in the initial block of five shocks. CONCLUSIONS: Prepulses may be useful in diminishing the pain associated with the therapeutic electrical shocks used to treat cardiac arrhythmias.

Adult↗