Search

Sign and goal tracker animals show different behavioral patterns in response to conditioned stimuli, which may be driven by different neural circuits involved in processing stimuli. Here, we explored whether sign and goal-tracker profiles implicated different brain regions and responses to incentive salience of stimuli. We performed three experiments using male Wistar rats. Experiment 1 showed that lesioning the medial prefrontal cortex increased the prevalence of the goal-tracker phenotype. Experiment 2 assessed the developmental trajectory of the salience incentive attribution to a conditioned stimulus, showing that increased incentive salience of stimuli increased the prevalence of the sign-tracker phenotype in mature, but not preadolescent rats. In experiment 3, the functional impact of the medial prefrontal cortex circuits was analyzed with a latent inhibition procedure. Sign tracker rats showed a reduced latent inhibition to stimuli previously exposed when compared to goal tracker or intermediate rats. The overall results of this study highlight a key role of the medial prefrontal cortex for sign tracking behavior. The expression of sign and goal tracker phenotypes changed after lesion to the medial prefrontal cortex (experiment 1), differed across development (experiment 2), and showed differences in the attentional processes to previously exposed stimuli, as preexposure to CS was ineffective in sign tracker animals (experiment 3). These data indicate that the responses to the incentive salience of stimuli in sign tracker and goal tracker profiles are likely driven by different neural circuitry, with a different role of prefrontal cortical function. [ABSTRACT FROM AUTHOR]

Goldfish (Carassius auratus) were trained in different place-finding tasks as a means of analyzing their ability to encode the geometric and the featural properties of the environment. Results showed that goldfish could encode and use both geometric and featural information to navigate. Goldfish trained in a maplike, or relational, procedure encoded both types of information in a single representation. In contrast, fish trained in a directly cued procedure developed 2 independent and competing strategies. These results suggest that the geometric properties of the spatial arrangement and discrete landmarks are sensitive to encoding in a maplike or relational system, whereas different sources of spatial information are encoded in a single and flexible representation of the environment. [ABSTRACT FROM AUTHOR]

• Goal directed behavior and habit are differentially affected for 2 models of PD. • 6-OHDA neurotoxic model disrupted Stimulus-Response mechanism. • LPS neuroinflammatory model facilitated habit formation. • Both models are involved in Substantia Nigra and striatum dopamine depletion. • Both models could help to understand different stages in PD. Instrumental conditioning involves two different processes: Goal-directed behavior, characterized by its dependence on the causal relationship between action and outcome and the sensitivity of actions to changes in the value of the outcome; and habits, characterized for its persistence and insensitivity to changes after conditioning. It is known that the dopaminergic system is involved in both kind of learning. The present experiments analyzed two animal models of Parkinson's disease. The 6-OHDA model causes selective damage of the catecholaminergic neurons, specifically affecting the dopaminergic neurons in nigro-striatal system. This model simulates degenerative process symptomatology of Parkinson's disease. On the other hand, the LPS model generates an inflammation process in the infusion area. This model simulates the early symptoms of this disorder, including neuroinflammation and microglia activation. In order to validate both parkinsonian models, we studied if 6-OHDA and LPS models cause the same behavioral effects. The results showed that the 6-OHDA model interfered with the process involved in habit formation. In contrast, animals treated with LPS showed a goal-directed learning deficit. Differences between these models could be due to the different effects on Substantia Nigra neurons. 6-OHDA model might disrupt the nigrostriatal pathway, while LPS could interfere on efferences and afferences to Substantia Nigra. [ABSTRACT FROM AUTHOR]