Residual lesions of operant behavior in monkeys following recovery from MPTP-induced Parkinson-like syndrome

Abstract

Studies of Parkinson's disease in recent years have made wide use of a model of Parkinson-like syndrome in animals, induced with N-methyl-4-phenyl-l,2,3,6-tetrahydropyridine (MPTP) [3][4][5]. The model has been used to study protective and compensatory substances in MPTP-induced syndrome [1, 2]. The aim of the present work was to study the residual effects of amiridine and K-34 on the symptomatology of MPTP syndrome.Experiments were carried out on 6 Macaca rhesus monkeys, 4 of which had been used 12 months previously to model MPTP-induced syndrome with subsequent recovery on amiridine and K-34.Monkey I received 10 MPTP injections (0.2 mg/kg), to a total dose of 22 mg; treatment with amiridine was started immediately after the course of MPTP had finished, and the animal received 15 doses of amiridine (0. Experimental studies of changes in cognitive functions were carried out using a simplified Viskonsinskii test device. This device consisted of a cell in which the monkey was presented with a transparent hollow cube with an edge length of 15 cm. One of the cube walls had an opening 12 cm in diameter. The cube could be fixed in front of the monkey in 5 different positions: with the opening above, towards, to the right, to the left, and away from the animal. Reinforcement was placed within the cube and consisted of standard monkey feed (carrots, beetroot, potato, dried fruit, etc.) and pieces of feed weighing 4-6 g. Experiments were carried out in the presence of the investigator, who assessed the monkeys' behavior visually and recorded the experimental results.Each experiment consisted of 27 presentations of the cube. With the aim of preventing the monkeys from learning the sequence of cube positions, positions were selected at random. The following parameters were recorded for each presentation and each response made by the animal: the latent period of the response, i.e., the time taken by the monkey to perform a correct response and receive reinforcement; the number of mistakes; and the distribution of mistakes. Errors were defined as attempts to take the reinforcement through the walls of the cube. Monkeys Nos. 3 and 4 were tested in the apparatus after modeling of MPTP syndrome.Studies of the dynamic characteristics of operant responses (hand movements) in the experimental apparatus were performed using an IBM PC/AT personal computer running a program developed in our department. The apparatus also contained two standard VGA monitors: one for presentation of visual stimuli (this monitor was located 50 cm from the animals' eyes), the second for monitoring the experiment. Reinforcement (fruit juice) was provided using an automatically controlled peristaltic pump. During the experiment, animals were kept in a primate chair fitted with a lever on the left-hand side; the monitor and chair were placed in a darkened room. The lever position was digitized using an analog-to-digital converter, with readings taken every 10 msec. Data corresponding to the level movement trajectory were recorded on disk for subsequent analy...

Early Changes in Saccadic Eye Movement in Hemiparkinsonian MPTP-Treated Monkeys

“…Experiments with the MPTP model also demonstrated increased latencies of visually guided saccades and decreased amplitude and accuracy for these saccades as well as a notable decline in their peak velocity (Brooks et al, 1986;Kori et al, 1995;Latanov, Tereshchenko, Yudin, & Shul'govskii, 1998;Porras et al, 2012;Shcultz et al, 1989;Shul'govskii et al, 1994;Slovin et al, 1999;Tereshchenko et al, 2002).…”