Cartling B
Department of Theoretical Physics, Royal Institute of Technology, Stockholm, Sweden.
Behav Brain Res. 1997 Aug;87(1):49-58. doi: 10.1016/s0166-4328(96)02268-1.
A neural mechanism for control of computational dynamics underlying the generation of meaning in cognitive processes is demonstrated. Meaning derives from recognition of connections between items in related conceptual classes of the neural representation in the brain. It is generated from a stimulated item in one conceptual class by an associative process in which linked items in related conceptual classes are activated in parallel. The complexity of the dynamics of this process varies between exploratory and direct retrieval modes. It is shown that the dynamics mode of the generation of meaning can be controlled by the neuronal adaptivity, i.e., the coupling strength between neuronal activity and excitability. Neuronal adaptivity in turn is controlled by neuromodulators in the brain. An autonomous regulation of the dynamics can be accomplished by an activity-dependent release of neuromodulators. The generation of a sequence of bifurcations from an initial exploratory phase to a final retrieval of appropriate item in each conceptual class is demonstrated. The time required for retrieval is shown also to depend on synaptic coupling strengths. The involvement of neuromodulatory systems in cognitive processes has long been observed but the underlying mechanisms not known. The present model describes a mechanism based on the primary effect observed of neuromodulators, viz. that on neuronal adaptivity, and is shown to be consistent with many neuroanatomical, neurophysiological and behavioural observations.
本文展示了一种神经机制，该机制可控制认知过程中意义生成背后的计算动力学。意义源自对大脑中神经表征相关概念类别中项目之间联系的识别。它是由一个概念类别中的受刺激项目通过关联过程产生的，在这个过程中，相关概念类别中的相关联项目会被并行激活。这个过程动力学的复杂性在探索性和直接检索模式之间有所不同。研究表明，意义生成的动力学模式可以由神经元适应性控制，即神经元活动与兴奋性之间的耦合强度。而神经元适应性又反过来受大脑中的神经调质控制。通过神经调质的活动依赖性释放，可以实现对动力学的自主调节。本文展示了从初始探索阶段到每个概念类别中适当项目的最终检索所产生的一系列分岔。检索所需的时间也显示取决于突触耦合强度。神经调节系统在认知过程中的参与早已被观察到，但其潜在机制尚不清楚。当前模型描述了一种基于观察到的神经调质主要作用的机制，即对神经元适应性的作用，并被证明与许多神经解剖学、神经生理学和行为学观察结果一致。
