Attenuation of auditory startle and prepulse inhibition by unexpected changes in ambient illumination through dopaminergic mechanisms

Different effects of unexpected changes in environmental conditions on prepulse inhibition in rats and humans

“…The first experiment is designed to reproduce the results obtained by Schmajuk et al [26], namely the reduction of the startle response and PPI after a change of illumination in the experimental condition. Some changes to the Schmajuk et al [26] design were introduced in this experiment: first, a 90 dB SPL prepulse was used instead of a 70 dB SPL stimulus, since in pilot studies in our laboratory no consistent PPI was found with the latter prepulse intensity.…”

“…Our aim in this paper is to analyze the effect that environmental changes -namely, a variation in the illumination conditions-have on the startle response and PPI in both rats and humans. Based on the results reported by Schmajuk et al [26] we expect that exposure to novel environmental situations would produce a transient increase in dopamine release in both cortical and subcortical regions [24] and therefore cause a reduction in PPI in both rats and humans. However, it is possible that the effects on PPI may depend on the type of novel stimulus that appears in the experimental situation, since previous results with rats indicate that PPI is reduced after a dark to light transition, but not when the change is from light to dark [26].…”

“…Based on the results reported by Schmajuk et al [26] we expect that exposure to novel environmental situations would produce a transient increase in dopamine release in both cortical and subcortical regions [24] and therefore cause a reduction in PPI in both rats and humans. However, it is possible that the effects on PPI may depend on the type of novel stimulus that appears in the experimental situation, since previous results with rats indicate that PPI is reduced after a dark to light transition, but not when the change is from light to dark [26]. It is possible that this lack of symmetry in animals is restricted to the transition from dark to light due to the increase in surrounding visual stimuli that occurs with a sudden illumination increase.…”

“…According to the results presented above, external changes involving the introduction of new elements in the experimental situation, such as a manipulation of the illumination condition in the area where the subject is located, would impact the dopaminergic activity and produce a modulating effect on PPI [26]. Our aim in this paper is to analyze the effect that environmental changes -namely, a variation in the illumination conditions-have on the startle response and PPI in both rats and humans.…”

“…Schmajuk, Larrauri, De la Casa, and Levin (2009) demonstrated that this dopaminergic modulation of PPI in rats can be influenced by manipulating the experimental context, specifically by introducing changes in the ambient lighting condition that include novel elements. In this paper we analyse the effects of introducing changes in context illumination on PPI in male rats (Experiment 1) and humans (Experiment 2).…”