Cortico-basal ganglia circuit mechanism for a decision threshold in reaction time tasks
Cortico-basal ganglia circuit mechanism for a decision threshold in reaction time tasks
复制标题
DOI：
10.1038/nn1722
复制
发表时间：
2006-07-01
影响因子：
25
通讯作者：
Wang, Xiao-Jing
中科院分区：
文献类型：
--
作者：
Lo, Chung-Chuan;Wang, Xiao-Jing
来自灵长类神经生理学和建模的越来越多的证据表明，在反应时间任务中，当选择性皮质神经群体的放电率达到阈值时，就会做出感知选择。这引发了两个问题：阈值的神经基础是什么，以及它如何根据行为需求进行适应性调整？利用一个基于生物物理的脉冲神经元网络模型，我们表明上丘的局部动力学产生了一种全或无的爆发式反应，该反应标志着上游皮质神经元的阈值跨越。此外，阈值水平仅微弱地依赖于皮质 - 上丘通路的效能。相比之下，阈值和奖励获取率对皮质 - 纹状体突触的强度敏感，因此可以通过其进行最佳调整，而皮质 - 纹状体突触已知可由多巴胺依赖性可塑性改变。我们的模型提供了一个框架来描述反应时间任务中的主要计算步骤，并表明不同的大脑通路对于决策阈值的检测和调整至关重要。
Growing evidence from primate neurophysiology and modeling indicates that in reaction time tasks, a perceptual choice is made when the firing rate of a selective cortical neural population reaches a threshold. This raises two questions: what is the neural substrate of the threshold and how can it be adaptively tuned according to behavioral demands? Using a biophysically based network model of spiking neurons, we show that local dynamics in the superior colliculus gives rise to an all-or-none burst response that signals threshold crossing in upstream cortical neurons. Furthermore, the threshold level depends only weakly on the efficacy of the cortico-collicular pathway. In contrast, the threshold and the rate of reward harvest are sensitive to, and hence can be optimally tuned by, the strength of cortico-striatal synapses, which are known to be modifiable by dopamine-dependent plasticity. Our model provides a framework to describe the main computational steps in a reaction time task and suggests that separate brain pathways are critical to the detection and adjustment of a decision threshold.