Dentate gyrus-selective colchicine lesion and performance in temporal and spatial tasks.
The effects of multiple-site, intradentate, colchicine injections on the performance of a temporal, 'differential reinforcement of low rates of responding' (DRL-20s) task and a spatial, 'delayed non-matching-to-place' (DNMTP) task in a plus-maze were investigated in rats trained in both tasks prior to the lesion. Quantitative analysis revealed a greater than 86% reduction in the dentate gyrus (DG) of the colchicine-injected rats compared to the sham-operated controls. Dentate gyrus damage rendered rats less efficient than sham-operated controls in the performance of the DRL-20s task. The DRL inter-response time (IRT) distribution for the DG-lesioned rats and the sham-operated controls was similar; however, while the distribution peak for the control rats was 20s, it was 16s for the DG-lesioned rats, indicating that the latter rats underestimated time. Performance of the DG-lesioned rats was also disrupted in the DNMTP task. However, DG-lesioned rats recovered control levels of performance during repeated training with an intertrial interval equal to 3s. An increase in intertrial interval in lesioned and sham-operated controls disrupted performance in both groups; however, while DG-lesioned rats performed at chance levels when the intertrial interval was increased to 4min or longer, the sham-operated controls performed at chance levels only when the intertrial interval was increased to 16min. These results seem most parsimoniously interpreted following the cognitive map theory of hippocampal function.
Costa
Valéria Catelli Infantozzi
VC
Setor de Psicobiologia, Departamento de Psicologia e Educação da Faculdade Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. dos Bandeirantes, Brazil. costaval@terra.com.br
Bueno
José Lino Oliveira
JL
Xavier
Gilberto Fernando
GF
D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D001927:Brain Diseases / Q000503:physiopathology; D003078:Colchicine / Q000633:toxicity*; D003714:Denervation; D018891:Dentate Gyrus / Q000293:injuries / Q000473:pathology / Q000502:physiology*; D008297:Male; D018782:Maze Learning / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time / Q000187:drug effects; D012054:Reinforcement, Psychology; D013028:Space Perception / Q000187:drug effects*; D013037:Spatial Behavior / Q000187:drug effects*; D013997:Time Factors
D003078:Colchicine