Baston Chiara, Ursino Mauro
Department of Electrical, Electronic and Information Engineering "Guglielmo Marconi", University of Bologna, Viale Risorgimento 2, 40136 Bologna, Italy.
Comput Intell Neurosci. 2015;2015:187417. doi: 10.1155/2015/187417. Epub 2015 Nov 10.
The basal ganglia (BG) are a subcortical structure implicated in action selection. The aim of this work is to present a new cognitive neuroscience model of the BG, which aspires to represent a parsimonious balance between simplicity and completeness. The model includes the 3 main pathways operating in the BG circuitry, that is, the direct (Go), indirect (NoGo), and hyperdirect pathways. The main original aspects, compared with previous models, are the use of a two-term Hebb rule to train synapses in the striatum, based exclusively on neuronal activity changes caused by dopamine peaks or dips, and the role of the cholinergic interneurons (affected by dopamine themselves) during learning. Some examples are displayed, concerning a few paradigmatic cases: action selection in basal conditions, action selection in the presence of a strong conflict (where the role of the hyperdirect pathway emerges), synapse changes induced by phasic dopamine, and learning new actions based on a previous history of rewards and punishments. Finally, some simulations show model working in conditions of altered dopamine levels, to illustrate pathological cases (dopamine depletion in parkinsonian subjects or dopamine hypermedication). Due to its parsimonious approach, the model may represent a straightforward tool to analyze BG functionality in behavioral experiments.
基底神经节（BG）是一种与动作选择有关的皮质下结构。这项工作的目的是提出一种新的基底神经节认知神经科学模型，该模型力求在简单性和完整性之间实现简约的平衡。该模型包括基底神经节回路中运作的3条主要通路，即直接（Go）通路、间接（NoGo）通路和超直接通路。与先前模型相比，主要的创新点在于使用双项赫布规则来训练纹状体中的突触，该规则完全基于多巴胺峰值或谷值引起的神经元活动变化，以及胆碱能中间神经元（其自身受多巴胺影响）在学习过程中的作用。展示了一些关于几个典型案例的示例：基础条件下的动作选择、存在强烈冲突时的动作选择（此时超直接通路的作用显现）、相位多巴胺诱导的突触变化，以及基于先前奖惩历史学习新动作。最后，一些模拟展示了模型在多巴胺水平改变的条件下的运作情况，以说明病理案例（帕金森病患者的多巴胺耗竭或多巴胺用药过量）。由于其简约的方法，该模型可能是行为实验中分析基底神经节功能的一种直接工具。
