Schmajuk N A, Moore J W
Department of Psychology, Northwestern University, Evanston, IL 60201.
Behav Brain Res. 1989 Mar 1;32(2):173-89. doi: 10.1016/s0166-4328(89)80083-x.
The effects of various hippocampal manipulations on the classically conditioned nictitating membrane (NM) response were simulated by a real-time attentional-associative model. The model incorporates: (a) a mechanism capable of establishing associations between conditioned (CS) and unconditioned stimuli (US) and between two CSs, (b) a mechanism that combines CS-CS and CS-US associations and builds 'computational cognitive maps', (c) an attentional rule that 'tunes in' relevant CSs and 'tunes out' irrelevant CSs, (d) performance rules that convert learning variables into topography of the rabbit NM response, and (e) rules that convert learning variables into neuronal firing. The present study explored three hypotheses regarding hippocampal function: (a) hippocampal lesions (HL) impair the 'tuning out' of irrelevant stimuli, (b) hippocampal stimulation (HS) and hippocampal long-term potentiation (LTP) facilitate the 'tuning in' of relevant stimuli, and (c) hippocampal unit activity is proportional to the instantaneous value of associative variables that participate in the 'tuning' mechanisms. Computer simulations for the HL case were carried out for conditioning under different interstimulus intervals (ISI) with different types of US, discrimination reversal, and sensory preconditioning. Computer simulations for the HS and LTP case were carried out for acquisition of delay conditioning and of classical discrimination. In addition, simulations of hippocampal unit activity during acquisition and extinction are presented. Under the 'tuning out' hypothesis for the HL case, the model proved capable of simulating a large portion of the experimental data, showing discrepancies with relevant literature only when describing HL effects on trace conditioning with shock US under short and long ISIs, trace conditioning with air puff US under long ISIs, discrimination reversal and sensory preconditioning. Under the 'tuning in' hypothesis regarding the HS and LTP case, the model proved capable of simulating acquisition of delay conditioning but not acquisition of classical discrimination. Under the assumption that neuronal activity is proportional to the instantaneous value of associative variables, the model is able to simulate hippocampal unit activity.
通过一个实时注意力关联模型模拟了各种海马体操作对经典条件反射性瞬膜（NM）反应的影响。该模型包括：（a）一种能够在条件刺激（CS）和非条件刺激（US）之间以及两个CS之间建立关联的机制；（b）一种将CS-CS和CS-US关联结合起来并构建“计算认知地图”的机制；（c）一种注意力规则，该规则“调谐到”相关CS并“排除”不相关CS；（d）将学习变量转换为兔NM反应地形图的表现规则；以及（e）将学习变量转换为神经元放电的规则。本研究探讨了关于海马体功能的三个假设：（a）海马体损伤（HL）会损害对无关刺激的“排除”；（b）海马体刺激（HS）和海马体长时程增强（LTP）会促进对相关刺激的“调谐到”；（c）海马体单位活动与参与“调谐”机制的关联变量的瞬时值成正比。针对HL情况进行了计算机模拟，模拟了在不同刺激间隔（ISI）下使用不同类型US的条件作用、辨别反转和感觉预条件作用。针对HS和LTP情况进行了计算机模拟，模拟了延迟条件作用和经典辨别的习得。此外，还展示了习得和消退过程中海马体单位活动的模拟。在HL情况的“排除”假设下，该模型被证明能够模拟大部分实验数据，仅在描述HL对短ISI和长ISI下电击US的痕迹条件作用、长ISI下吹气US的痕迹条件作用、辨别反转和感觉预条件作用的影响时与相关文献存在差异。在关于HS和LTP情况的“调谐到”假设下，该模型被证明能够模拟延迟条件作用的习得，但不能模拟经典辨别的习得。在神经元活动与关联变量的瞬时值成正比的假设下，该模型能够模拟海马体单位活动。
