Abstract
Prepulse inhibition (PPI) is the suppression of the startle reflex when the intense startling stimulus is shortly preceded by a weaker non-startling stimulus (prepulse). In rats, the auditory precedence-effect-induced perceived spatial separation between the fear-conditioned prepulse and a noise masker facilitates selective attention to the prepulse and enhances PPI. However, whether the perceptual separation between the prepulse and a noise masker can also enhance PPI in humans remains unclear. Also, the relationship between the PPI enhancement and the change in early cortical representations of prepulse signals is unclear. This study for the first time reveals that in a sound-attenuated laboratory environment, relative to the listening condition with perceptual co-location between the prepulse stimulus and a noise-masking stimulus, the perceptual separation between the two stimuli significantly enhances the group-mean PPI. More importantly, the early cortical responses (N1/P2 complex) to the prepulse stimulus are also enhanced by the perceptual separation in most listeners, and the perceptual-separation-induced enhancement of the N1 component is positively correlated with the perceptual-separation-induced PPI enhancement. Thus, the perceptual separation enhances PPI through facilitating selective attention to the prepulse, leading to an enhancement of the early cortical representation of the prepulse signal in temporal auditory cortical fields.
Highlights
The startle reflex is the whole-body reflexive response to sudden and intense sensory stimuli, which disrupts cognitive/behavioral performances[1]
The precedence effect for speech sounds can occur at any lead-lag delays shorter than the echo threshold, it has been confirmed that when a 3-ms delay is introduced beteween the leading speech sound and the correlated lagging speech sound, the leading and lagging speech sounds are well fused perceptually, and a single speech-sound image is perceived as coming from the location of the leading speech sound[21,22,23,24]
At the ISI of either 60 or 120 ms, the Prepulse inhibition (PPI) magnitude was larger in the majority of participants when the prepulse and the noise masker were perceptually separated than when the prepulse and the noise masker were perceptually co-located
Summary
The startle reflex is the whole-body reflexive response to sudden and intense sensory stimuli, which disrupts cognitive/behavioral performances[1]. If the time delays between the arrival of the direct wave and each of the reflected waves are sufficiently short (e.g., 1–10 ms or more, depending on the nature of the stimulus), due to the perceptual capture of the attributes of the delayed and correlated reflections by the direct wave from the source[19], listeners typically perceive a single “fused” image of the source located at or near the original site of the source. This phenomenon has been generally known as the precedence effect[20,21]. In the rodent model of schizophrenia induced by social isolation rearing, perceptual separation-induced PPI enhancement completely disappears[14,15,18]
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