Simple and complex discrimations: protein malnutrion and stimulation effects

Author(s)

Elimar Adriana de Oliveira Feliciano

• Document type: Doctoral Thesis
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (PCARP/BC)
• Defense date: 2007-02-02

Examining board members

Luiz Marcellino de Oliveira; Jose Lino Oliveira Bueno; León Federico Cintra Mcglone; Deisy das Gracas de Souza; Gerson Aparecido Yukio Tomanari

• Advisor: Luiz Marcellino de Oliveira

Abstract

Nutritional deficiency in early life results in morphologic, biochemical and behavioral alterations. The behavioral consequences of malnutrition can be partially recovered by environmental conditions. The objective of Experiment 1 was the analysis the effects of malnutrition in simple discrimination procedures. Experiment 2 was addressed to study the effects of malnutrition and environmental stimulation (handling and environment) effects on simple and complex discriminations. In both experiments, 16% (Controls ? C) or 6% (Malnourished ? D) protein diets were offered to rats from birth to age day 35. From that age up to the end of the experiments, commercial diets were available to the rats. Before age day 85, the ad libitum weights of the rats were reduced to 85% of the medium weight with water deprivation. In Experiment 1, control and malnourished rats were randomly assigned to the sound and light discriminative stimuli (SDS). Bar presses were reinforced with water during the light or sound stimulus presentation and not reinforced in the absence of these stimuli (SD). After each animal obtained the discrimination index of 80% in 6 consecutive sessions, the reversion of the discrimination initiated. In the reversion, bar presses were reinforced in the period of light or sound off. There was an effect sessions in the discrimination index (DI) in the discrimination as well as in the reversion phase for controls and malnourished. There was no diet effect or type of stimulus effect. In the first session of reversion phase, all groups showed differences in the rate of bar presses, in the SD as well in the SD when compared with the 6 last sessions of the discrimination phase. In the Experiment 2, half of the pups were stimulated from birth up to 35 days of age. The sessions were initiated after the animals reached the same weight reduction (85%) as in the Experiment 1. In Experiment 2, two boxes with a bar in the frontal wall and 3 tunnels in the opposite wall were used. The stimulus sounds (constant or interrupted) and figures of triangles and lines were presented above the tunnels. Bar presses and nose pokes in the tunnels were shaped in each animal. In each trial, bar presses were followed by the presentations of the line and triangle stimuli in two tunnels, and in the third tunnel no stimulus was presented. Nose pokes in the tunnel with the SD line were reinforced with water and the responses in the tunnel with the triangle or without stimulus (SD) were not reinforced. After each animal reached the criterion of 80% of correct responses, the reversion of the discrimination was initiated. During the reversion phase, nose poke responses were reinforced in the tunnel with the triangle and not reinforced in the tunnels with line or without stimulus. After the same hit criterion of the discrimination phase was reached by each animal, the training of the conditional discrimination initiated. In the conditional phase, after the bar presses a continuous or discontinuous sound stimuli were presented in the central tunnel, and the line or triangle stimuli were introduced above any of the tunnels, and one of the tunnels remained with no stimulus. During the presentation of the conditional stimulus continuous sound, nose pokes in the tunnel with the line were reinforced and responses in the other tunnels were not reinforced. During the presentation of the conditional stimulus discontinuous sound, nose pokes in the tunnel with the triangle were reinforced and the others responses in the tunnels were not reinforced. There was a diet effect in the discrimination phase and more sessions were required for the malnourished animals to reach the criterion, compared to the controls. In the reversion phase, the malnourished not stimulated early in life showed lesser performance in comparison with the others groups. None of the groups showed improvement of the performance in the conditional discrimination phase. The results shows that other procedures will be necessary to improve the acquisition of more complex discriminations (AU)