Arizona State University, PO Box 871104, Tempe, AZ 85287-1104, USA.
Behav Brain Funct. 2012 Dec 13;8:59. doi: 10.1186/1744-9081-8-59.
Deficient operant extinction has been hypothesized to be constitutive of ADHD dysfunction. In order to elucidate the behavioral mechanisms underlying this deficit, the performance of an animal model of ADHD, the spontaneously hypertensive rat (SHR), was compared against the performance of a control strain, the Wistar-Kyoto rat (WKY) during extinction.
Following extensive training of lever pressing under variable interval schedules of food reinforcement (reported previously), SHR and WKY rats were exposed to two sessions of extinction training. Extinction data was analyzed using the Dynamic Bi-Exponential Refractory Model (DBERM) of operant performance. DBERM assumes that operant responses are organized in bouts separated by pauses; during extinction, bouts may decline across multiple dimensions, including frequency and length. DBERM parameters were estimated using hierarchical Bayesian modeling.
SHR responded more than WKY during the first extinction session. DBERM parameter estimates revealed that, at the onset of extinction, SHR produced more response bouts than WKY. Over the course of extinction, response bouts progressively shortened for WKY but not for SHR.
Based on prior findings on the sensitivity of DBERM parameters to motivational and schedule manipulations, present data suggests that (1) more frequent response bouts in SHR are likely related to greater incentive motivation, and (2) the persistent length of bouts in SHR are likely related to a slower updating of the response-outcome association. Overall, these findings suggest specific motivational and learning deficits that may explain ADHD-related impairments in operant performance.
操作消退不足被假设为 ADHD 功能障碍的组成部分。为了阐明这种缺陷的行为机制，比较了 ADHD 动物模型——自发性高血压大鼠（SHR）与对照品系——Wistar-Kyoto 大鼠（WKY）在消退期间的表现。
在广泛的杠杆按压训练后，根据可变间隔的食物强化时间表（之前报道过），SHR 和 WKY 大鼠接受了两次消退训练。使用操作性能的动态双指数 Refractory 模型（DBERM）分析消退数据。DBERM 假设操作反应组织成由停顿分隔的突发；在消退期间，突发可能会在多个维度上下降，包括频率和长度。使用分层贝叶斯建模估计 DBERM 参数。
SHR 在第一次消退训练中比 WKY 反应更多。DBERM 参数估计表明，在消退开始时，SHR 产生的反应突发比 WKY 多。在消退过程中，反应突发逐渐缩短，但 SHR 没有。
基于 DBERM 参数对动机和时间表操作的敏感性的先前发现，目前的数据表明，（1）SHR 中更频繁的反应突发可能与更大的激励动机有关，（2）SHR 中反应突发的持续时间较长可能与反应-结果关联的更新较慢有关。总体而言，这些发现表明特定的动机和学习缺陷，可能解释 ADHD 相关的操作表现受损。
