Academic journal article Cognitive, Affective and Behavioral Neuroscience

Precedence-Effect-Induced Enhancement of Prepulse Inhibition in Socially Reared but Not Isolation-Reared Rats

Academic journal article Cognitive, Affective and Behavioral Neuroscience

Precedence-Effect-Induced Enhancement of Prepulse Inhibition in Socially Reared but Not Isolation-Reared Rats

Article excerpt

Attention to a prepulse presented shortly before a startling stimulus enhances prepulse inhibition (PPI) of startle in normal people, but not in schizophrenics. Fear conditioning for the prepulse enhances PPI in socially reared, but not isolation-reared, rats. In humans, selective attention to acoustic signals against masking can be facilitated by precedence-effect-induced perceived spatial separation between the signal and the masker. This study investigated whether perceived spatial separation between a prepulse and a noise masker enhances PPI in socially reared rats and isolation-reared rats. The results show that both PPI and conditioning-induced PPI enhancement were larger in socially reared rats than in isolation-reared rats. More important, in socially reared, but not isolation-reared, rats, a further PPI enhancement was induced by precedence-effect-induced perceived separation between a prepulse and a masker only after the prepulse became fear conditioned. Thus, perceived separation facilitates normal rats' attention to a conditioned prepulse and enhances PPI. Isolation rearing impairs rats' ability to attend to ecologically significant acoustic events.

(ProQuest: ... denotes formula omitted.)

Prepulse inhibition (PPI) is the normal reduction of the amplitude of the startle reflex in response to an intense startling stimulus (pulse) when the startling stimulus is preceded a short time before by a weaker, nonstartling sensory stimulus (prepulse) (Buckland, Buckland, Jamieson, & Ison, 1969; Pickney, 1976; for reviews, see Hoffman & Ison, 1980; Ison & Hoffman, 1983; L. Li & Yue, 2002). Graham (1975) proposed a protection-of-processing theory for justifying the function of PPI that dampens the disruptive influence from startle. Since consequences of PPI include the reduction of behavioral responses to disruptive stimuli by regulating the motor system and/or the premotor system, PPI has been generally recognized as a simple operational measure of sensorimotor gating. The magnitude of PPI has also been widely used as a measure of the salience of the prepulse stimulus in rodents (Barsz, Ison, Snell, & Walton, 2002; Carlson & Willott, 1996; J. Huang et al., 2007; Ison, Agrawal, Pak, & Vaughn, 1998; Ison & Bowen, 2000; Leitner & Girten, 1997; L. Li, Korngut, Frost, & Beninger, 1998; Turner, Brozoski, Bauer, Parrish, & Myers, 2006; Young & Fechter, 1983; Zou, Huang, Wu, & Li, 2007).

Although the pathway mediating PPI is located in the brainstem (for a review, see L. Li & Yue, 2002), PPI can be modulated by higher order central processing. In humans, selective attention to the prepulse enhances PPI (e.g., Filion & Poje, 2003; Heekeren, Meincke, Geyer, & Gouzoulis-Mayfrank, 2004; Schell, Wynn, Dawson, Sinaii, & Niebala, 2000; Thorne, Dawsona, & Schell, 2005), and PPI is more pronounced when the prepulse is emotionally salient than when it is a neutral stimulus (Bradley, Codispoti, & Lang, 2006; Bradley, Cuthbert, & Lang, 1993). In rats with normal rearing, when the prepulse becomes fear conditioned (J. Huang et al., 2007; N. X. Li et al., 2008; Zou et al., 2007) or fear-extinction conditioned (Röskam & Koch, 2006), PPI is markedly enhanced, suggesting that the facilitation of rats' selective attention to the prepulse and/or the spatial location of the prepulse can be built up when the prepulse becomes ecologically significant. To further confirm the effects of selective attention to a prepulse on PPI in rats, new testing paradigms, in which selective attention is clearly involved, need to be established.

In a noisy, reverberant environment, listeners receive not only sound waves that directly emanate from various sources, but also reflections from surfaces at various locations. In such an environment, to perceptually segregate a target signal from other disruptive stimuli, perceptual integration of correlated sound waves is critical. …

Search by... Author
Show... All Results Primary Sources Peer-reviewed

Oops!

An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.