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Highlights: [•] Dls has been associated to S–R or habits and the dms with controlled processes. [•] This study analyzed if dls could be involved in cognitive processes. [•] Results showed that dls is important for the retrieval of overtrained association. [•] However, it is not necessary for retrieval processes requiring increased attention. [•] Data give support for theories of failure retrieval of LI. [ABSTRACT FROM AUTHOR]

Abstract: Recent results have demonstrated that the mammalian hippocampus and the dorso-lateral telencephalon of ray-finned fishes share functional similarities in relation to spatial memory systems. In the present study, we investigated whether the physiological mechanisms of this hippocampus-dependent spatial memory system were also similar in mammals and ray-finned fishes, and therefore possibly conserved through evolution in vertebrates. In Experiment 1, we studied the effects of the intracranial administration of the noncompetitive NMDA receptor antagonist MK-801 during the acquisition of a spatial task. The results indicated dose-dependent drug-induced impairment of spatial memory. Experiment 2 evaluated if the MK-801 produced disruption of retrieval of a learned spatial response. Data showed that the administration of MK-801 did not impair the retrieval of the information previously stored. The last experiment analyzed the involvement of the telencephalic NMDA receptors in a spatial and in a cue task. Results showed a clear impairment in spatial learning but not in cue learning when NMDA receptors were blocked. As a whole, these results indicate that physiological mechanisms of this hippocampus-dependent system could be a general feature in vertebrate, and therefore phylogenetically conserved. [Copyright &y& Elsevier]

• 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]