On the influence of baseline startle reactivity on the indexation of prepulse inhibition.

Abstract

Prepulse inhibition (PPI) of the startle reflex refers to the reduction of the reflexive startle response to an intense pulse stimulus when its presentation is shortly preceded by a weak prepulse stimulus. PPI is considered as a cross-species translational model of sensorimotor gating, and deficient PPI has been reported in a number of neuropsychiatric disorders. Although a part of the literature is based on the assumption that PPI is independent of the baseline startle reaction, there is accumulating evidence (Csomor et al., 2006;Sandner & Canal, 2007;Yee, Chang, Pietropaolo, & Feldon, 2005) that argues against such an independency. The authors systematically investigated whether PPI indexed as percentage or difference score is dependent on the magnitude of baseline startle reactivity in healthy human volunteers and in C57BL/6 mice. The results revealed that both indexations of PPI were affected by the magnitude of the baseline startle. The authors highlight the pitfalls of different methods to index PPI, especially when startle reactivity differs considerably between groups under comparison, and offer practical recommendations to satisfactorily deal with such baseline differences.

Individual difference in prepulse inhibition does not predict spatial learning and memory performance in C57BL/6 mice

“…We did not rely on the common measure of %PPI alone because of fear that it can be distorted by baseline startle reactivity (see Csomor et al, 2008b). To this end, only animals receiving the same categorization for both variables were included in the final segregation, which yielded 23 Bhigh-PPI^and 23 Blow-PPI^subjects.…”

“…To assist interpretation of the statistical outcomes, post-hoc analyses were performed based on the associated error terms taken from the overall ANOVA whenever appropriate. To better conform to the normality and variance homogeneity assumptions of parametric ANOVA, a natural logarithmic transformation (hereafter referred to as Bln-transformed^) (see Csomor et al, 2008b) was applied to the reactivity data obtained in the PPI experiment except for %PPI which was calculated based on the non-transformed data. All statistical analyses were carried out using SPSS for Windows (release 19, SPSS, Chicago, IL, USA) implemented on a PC running the Windows 7 operating system.…”

Is noise-induced cochlear neuropathy key to the generation of hyperacusis or tinnitus?

“…Each small symbol represents a different mouse, and mean PPI is shown for each group/subgroup by the bold symbols. DPOAE threshold for each animal is averaged frommagnitude in both humans and animals (Csomor et al 2008; but see Ison et al 1997). Thus we measured the thresholds and growth of ASR, without PPI, in the three groups of mice.…”

“…6). All statistical analyses of startle amplitude were performed with log-transformed startle response values (Csomor et al 2008) for a more normally distributed data set. A three-way ANOVA of exposure group, startle level, and test type revealed a significant all-way interaction [F(90,3001) ϭ 2.32, P Ͻ 0.0001], and significant simple main effect of exposure group was found for several startle level ϫ test type conditions (conditions in Fig.…”

The effect of nicotine on sensorimotor gating is modulated by a CHRNA3 polymorphism

“…No significant interaction of SOA×genotype (F(1,46)=1.38, p=.25, η p ²=.05), and no significant interaction of SOA×drug (F(1,46)=0.15, p=.90, η p ²=.003) was found. As startle reactivity (assessed by the mean amplitude of the first block of PA trials) tended to be different between genotype groups (p=.07, see Table 2) we added startle reactivity as an additional covariate to the statistical design (Csomor et al 2008). …”