Abstract
Prepulse inhibition (PPI) refers to the suppression of the startle reflex when the intense startling stimulus is shortly (20–500 ms) preceded by a weak non-startling stimulus (prepulse). Although the main neural correlates of PPI lie in the brainstem, previous research has revealed that PPI can be top-down modulated by attention. However, in the previous attend-to-prepulse PPI paradigm, only continuous prepulse but not discrete prepulse (20 ms) could elicit attentional modulation of PPI. Also, the relationship between the attentional enhancement of PPI and the changes in early cortical representations of prepulse signals is unclear. This study develops a novel attend-to-prepulse PPI task, when the discrete prepulse is set at 150 ms at a lead interval of 270 ms, and reveals that the PPI with attended prepulse is larger than the PPI with ignored prepulse. In addition, the early cortical representations (N1/P2 complex) of the prepulse show dissociation between the attended and ignored prepulse. N1 component is enhanced by directed attention, and the attentional increase of the N1 component is positively correlated with the attentional enhancement of PPI, whereas the P2 component is not affected by attentional modulation. Thus, directed attention to the prepulse can enhance both PPI and the early cortical representation of the prepulse signal (N1).
Highlights
The startle reflex is the whole-body reflexive response to sudden and intense sensory stimuli, such as an intense startling broadband noise (Landis and Hunt, 1939)
We have developed a novel attention-to-prepulse PPI paradigm to study the attentional modulation of PPI
The early cortical representations (N1/P2 complex) of the prepulse show dissociation between the attended and ignored prepulse, where N1 evoked by the attended prepulse was larger than that evoked by the ignored prepulse
Summary
The startle reflex is the whole-body reflexive response to sudden and intense sensory stimuli, such as an intense startling broadband noise (pulse) (Landis and Hunt, 1939). In the attention-to-prepulse PPI paradigm developed by Filion et al (1993) and replicated many times (Hazlett et al, 2003, 2007; Poje and Filion, 2021), subjects are presented with an intermixed series of high and low pitch tones and are instructed to count the number of longer-than-usual occurrences (7 s rather than 5 s) of one particular pitch (Filion et al, 1993) The rationale for this paradigm is that the task requires subjects to discriminate between to-be-attended and to-be-ignored pitches and sustain selective attention only to the to-be-attended pitch in order to determine its length (Filion et al, 1993). In this PPI paradigm, PPI is greater when the prepulse is attended than when ignored
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