Sensitivity to amphetamine in prepulse inhibition response requires a mature medial prefrontal cortex.

Prepulse inhibition (PPI) refers to the modulation of the startle response by the presentation of a weaker stimulus prior to the onset of the startle stimulus. This response is consolidated along the maturation process of the mesocortical system, where the dopamine neurotransmitter plays an important role. In fact, it has been reported that agonist and antagonist dopaminergic drugs are able to change PPI expression.

Conditioned increase of locomotor activity induced by haloperidol.

Dopamine antagonist drugs have profound effects on locomotor activity. In particular, the administration of the D2 antagonist haloperidol produces a state that is similar to catalepsy. In order to confirm whether the modulation of the dopaminergic activity produced by haloperidol can act as an unconditioned stimulus, we carried out two experiments in which the administration of haloperidol was repeatedly paired with the presence of distinctive contextual cues that served as a Conditioned Stimulus.

Reward devaluation disrupts latent inhibition in fear conditioning.

Three experiments explored the link between reward shifts and latent inhibition (LI). Using consummatory procedures, rewards were either downshifted from 32% to 4% sucrose (Experiments 1-2), or upshifted from 4% to 32% sucrose (Experiment 3). In both cases, appropriate unshifted controls were also included.

Reduced Prepulse Inhibition as a Biomarker of Schizophrenia.

The startle response is composed by a set of reflex behaviors intended to prepare the organism to face a potentially relevant stimulus. This response can be modulated by several factors as, for example, repeated presentations of the stimulus (startle habituation), or by previous presentation of a weak stimulus (Prepulse Inhibition [PPI]). Both phenomena appear disrupted in schizophrenia that is thought to reflect an alteration in dopaminergic and glutamatergic neurotransmission.

Effect of stress and attention on startle response and prepulse inhibition.

The startle reflex magnitude can be modulated when a weak stimulus is presented before the onset of the startle stimulus, a phenomenon termed prepulse inhibition (PPI). Previous research has demonstrated that emotional processes can modulate PPI and startle intensity, but the available evidence is inconclusive. In order to obtain additional evidence in this domain, we conducted two experiments intended to analyze the effect of induced stress and attentional load on PPI and startle magnitude.

Startle response and prepulse inhibition modulation by positive- and negative-induced affect.

The startle response, a set of reflex behaviours intended to prepare the organism to face a potentially threatening stimulus, can be modulated by several factors as, for example, changes in affective state, or previous presentation of a weak stimulus (a phenomenon termed Pre-Pulse Inhibition [PPI]). In this paper we analyse whether the induction of positive or negative affective states in the participants modulates the startle response and the PPI phenomenon. The results revealed a decrease of the startle response and an increase of the PPI effect when registered while the participants were exposed to pleasant images (Experiment 1), and an increase of the startle response and of the PPI effect when they were exposed to a video-clip of unpleasant content (Experiment 2).

Prepulse inhibition modulation by contextual conditioning of dopaminergic activity.

When a neutral stimulus is repeatedly paired with a drug, an association is established between them that can induce two different responses: either an opponent response that counteracts the effect of the drug, or a response that is similar to that induced by the drug. In this paper, we focus on the analysis of the associations that can be established between the contextual cues and the administration of dopamine agonists or antagonists. Our hypothesis suggests that repeated administration of drugs that modulate dopaminergic activity in the presence of a specific context leads to the establishment of an association that subsequently results in a conditioned response to the context that is similar to that induced by the drug.