ABSTRACT
Impaired temporal control is symptomatic of several neurological disorders; recently, it has been implicated in schizophrenia. An animal model of schizophrenia using 6-hydroxydopamine (6-OHDA) infused to the medial pre-frontal cortex (mPFC) was employed to examine its effects on temporal control. Twelve rats were trained on a peak-interval procedure (PIP) until stable patterns of behavior were obtained. Rats infused with 6-OHDA responded less during peak trials and their peak functions were flatter than sham rats. These results are consistent with similar studies with transgenic mice with increased striatal dopamine D2 receptor activity. Lesions in the mPFC decreased motivation to respond in a PIP. These effects may be considered analogous to negative symptoms of schizophrenia...
Subject(s)
Animals , Rats , Schizophrenia/etiology , Oxidopamine , Models, Animal , Reinforcement ScheduleABSTRACT
Four rats were subjected to chained fixed-ratio (FR), fixed-interval (FI) schedules of reinforcement (chain FR 5 FI). A FR schedule at one lever produced a discriminative stimulus (i.e., light) associated with an FI schedule of primary reinforcement (water) at the second response lever. The FR schedule was kept constant, whereas the FI length was changed from 10 to 60 s under five different experimental conditions. Increases in the FI length resulted in increases in pre-ratio pauses, but pauses in the FI tended to be a constant percentage of FI length. Data from this experiment indicate that pre-ratio pauses are also a function of the interreinforcement interval (IRI). Data from three experiments with chained FR 5 FI 60-s schedules indicate that pausing in the FI component of chained FR FI schedules with the FI as the second component of the chain may tend to disappear as the IRI duration increases.
Subject(s)
Animals , Rats , Reinforcement ScheduleABSTRACT
Whitaker, Lowe y Wearden reportaron un patrón diferencial de distribución de respuestas en un programa mixto de intervalo fijo de dos componentes, en función de la razón existente entre las duraciones de ambos intervalos. Estos resultados se explicaron aludiendo a la existencia de fuentes diferenciadas de control conductual para ambos componentes. En el presente estudio se pretendía contrastar esta hipótesis incluyendo una señal contextual que señalaba el programa de intervalo activo. Se utilizaron ocho ratas distribuidas en dos grupos con diferente razón y se compararon dos fases, una con discriminativo y otra sin este. Se encontró que la inclusión de la señal alteró la tasa de respuestas en los componentes de menor duración.
Whitaker, Lowe and Wearden reported a differential response pattern using a mixed two-component fixed-interval schedule of reinforcement, considering the ratio between the duration of both intervals. These results were explained in regards to the differential behavioral control sources for each component.This study was intended to contrast that hypothesis by including a contextual cue to mark the beginning of each active interval schedule. Eight rats were assigned to two groups with different ratio. In each ratio two conditions were in effect: one with a cue and the other without it. The results showed that the inclusion of the cue changed the response rate in the components with less duration.
Subject(s)
Rats , Association Learning , Conditioning, Operant , Discrimination Learning , Rats/psychology , Adaptation, Psychological , Behavior , Behavioral Sciences , Conditioning, PsychologicalABSTRACT
Num procedimento de discriminação condicional (DC) de característica positiva, um mesmo estímulo alvo A não é seguido de reforço quando apresentado sozinho, mas é seguido de reforço quando precedido de um estímulo X. Na DC de característica negativa, um mesmo estímulo alvo B é seguido de reforço quando apresentado sozinho, mas nunca quando precedido do estímulo Y. Nesta pesquisa, procurou-se examinar se uma informação amodal relativa a atributos básicos de estímulos, como a duração, tem capacidade de adquirir propriedades condicionais em animais. Ratos foram submetidos a procedimentos de DC positiva e negativa com estímulos X e Y de mesma modalidade física, uma luz, mas com durações diferentes: X= 15-seg e Y= 5-seg; as durações dos estímulos alvo foram A= 5-seg e B= 15-seg. Os resultados mostraram que os animais discriminaram as propriedades condicionais excitatórias (X) e inibitórias (Y) relativas, respectivamente, a duas durações diferentes de um mesmo estímulo, sustentando a hipótese de que a duração, um componente amodal de estímulo, pode ser associada a propriedades condicionais, em ratos.
In a feature positive conditional discrimination procedure, a stimulus A is not followed by reinforcement when presented alone, but it is always followed by reinforcement when it is preceded by stimulus X. In the negative conditional discrimination procedure, a stimulus B is always followed by reinforcement when presented alone, but it is not followed by reinforcement when preceded by stimulus Y. This research examined if amodal information dealing with basic attributes, as duration, has the capability to acquire conditional properties in animals. Rats were submitted to positive or negative conditional discrimination procedures with stimulus X and Y, which were of the same physical modality, a light, but with different durations: X= 15 seg e Y= 5 seg (and A=5 seg, B=15 seg). The results showed that the animals discriminated excitatory and inhibitory properties related, respectively, to two different durations of the same stimulus, supporting the hypothesis that the duration, as an amodal stimulus component, can be associated to conditional properties, in rats.
Subject(s)
Rats , Conditioning, Psychological , Discrimination, Psychological , Rats, Wistar , Reinforcement, Psychology , Time PerceptionABSTRACT
Recently,radiation-inducible gene therapy is one of new researchs in tumor therapy.In one side,the method associate radiation therapy with gene therapy,acting as synergistic effect;another side,radiation is targeting and inducible,implementing spatial and temporal control of gene expression.Related researchs have gained advances.This paper concisely reviews the status quo and the prospective applications.