Revista Mexicana de Análisis de la Conducta

Although Parkinson’s disease (PD) is classically considered to be a motor system disease, subtle cognitive impairments can be observed even during the early phases of PD. In this article we review behavioral and neurochemical studies on the cognitive alterations observed in rats treated with intranigral infusion of the neurotoxin MPTP. The critical role of dopamine release in the dorsal striatum and its modulation by adenosine receptors is also reviewed as a potential strategy to treat the cognitive disabilities of PD patients who do not improve with levodopa therapy. Most of the impairments presented by rats treated with intranigral infusion of MPTP are similar to those observed during the early phase of PD, when a moderate loss of nigral dopamine neurons (40-70%) results in sensory and memory defi cits with no major motor impair* This work was supported by CNPq, Fundação Araucária, Institutos de Milênio, and CAPES. Corresponding author: Laboratório de Fisiologia e Farmacologia do Sistema Nervoso Central, Departamento de Farmacologia, UFPR, C.P. 19.031, 81.531-980, Curitiba-PR, Brazil. Phone 55 RMAC_dic_2006.indd 219 21/05/2007 01:30:00 p.m. 220 DA CUNHA, PREDIGER, MIYOSHI AND TAKAHASHI ments. These animals also model the working memory and habit learning defi cits, with long-term spatial (episodic) memories being mostly spared as observed in non-demented PD patients. The intranigral infusion of MPTP in rats has led to the development of useful models, which do not present gross motor impairments that would otherwise compromise the interpretation of the performance of the animals in cognitive tasks.