Search

Recent studies support the idea that stimulus processing in latent inhibition can vary during the course of preexposure. Controlled attentional mechanisms are said to be important in the early stages of preexposure, while in later stages animals adopt automatic processing of the stimulus to be used for conditioning. Given this distinction, it is possible that both types of processing are governed by different neural systems, affecting differentially the retrieval of information about the stimulus. In the present study we tested if a lesion to the dorso-lateral striatum or to the medial prefrontal cortex has a selective effect on exposure to the future conditioned stimulus (CS). With this aim, animals received different amounts of exposure to the future CS. The results showed that a lesion to the medial prefrontal cortex enhanced latent inhibition in animals receiving limited preexposure to the CS, but had no effect in animals receiving extended preexposure to the CS. The lesion of the dorso-lateral striatum produced a decrease in latent inhibition, but only in animals with an extended exposure to the future conditioned stimulus. These results suggest that the dorsal striatum and medial prefrontal cortex play essential roles in controlled and automatic processes. Automatic attentional processes appear to be impaired by a lesion to the dorso-lateral striatum and facilitated by a lesion to the prefrontal cortex. [ABSTRACT FROM AUTHOR]

Desde Saussure, el lenguaje ha sido caracterizado como un sistema arbitrario en el que no existe ningún tipo de relación entre el significante y el significado, más allá de la que se genera por convención social. Los estudios más recientes no apoyan esta hipótesis por completo, sugiriendo que el cerebro humano es capaz de establecer relaciones entre sonidos y formas en función de las características de ambos. Esta capacidad de relacionar los sonidos y las formas está programada en nuestro cerebro desde que nacemos y posiblemente juega un papel importante en la adquisición del lenguaje. [ABSTRACT FROM AUTHOR]

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. This study was aimed to analyze the relationship between the adult medial prefrontal cortex (mPfc) and dopaminergic involvement in PPI throughout the life span. Specifically, the present experiment analyzed the effect of the administration of dopaminergic agonist amphetamine on PPI in two different age periods in Wistar rats: postnatal day (PND) 28 and PND 70. In this last period, we also explored the relationship between PPI response and amphetamine effects after mPfc lesion. The results showed that PPI was expressed in all groups and periods; however, amphetamine only modulated this effect during adulthood. We also found that the mPfc is essential to modulate PPI after amphetamine consumption. Besides, our results suggest a role for dopamine and mPfc as important modulators of PPI in adulthood. Nevertheless, this neurotransmitter could not be involved in the expression of PPI because the administration of a dopaminergic agonist was ineffective in PND-28 period. [ABSTRACT FROM AUTHOR]