Humphries Mark D
School of Psychology, University of Nottingham, Nottingham, UK
eNeuro. 2025 Apr 24;12(4). doi: 10.1523/ENEURO.0431-23.2024. Print 2025 Apr.
What the basal ganglia do is an oft-asked question; answers range from the selection of actions to the specification of movement to the estimation of time. Here, I argue that the basal ganglia do what they do is a less-asked but equally important question. I show that the output regions of the basal ganglia create a stringent computational bottleneck, both structurally, because they have far fewer neurons than do their target regions, and dynamically, because of their tonic, inhibitory output. My proposed solution to this bottleneck is that the activity of an output neuron is setting the weight of a basis function, a function defined by that neuron's synaptic contacts. I illustrate how this may work in practice, allowing basal ganglia output to shift cortical dynamics and control eye movements via the superior colliculus. This solution can account for troubling issues in our understanding of the basal ganglia: why we see output neurons increasing their activity during behavior, rather than only decreasing as predicted by theories based on disinhibition, and why the output of the basal ganglia seems to have so many codes squashed into such a tiny region of the brain.
基底神经节的功能是一个常被问到的问题；答案从动作选择到运动规范再到时间估计不等。在这里，我认为基底神经节为何如此运作是一个较少被问到但同样重要的问题。我表明，基底神经节的输出区域在结构上造成了一个严格的计算瓶颈，因为它们的神经元数量比其目标区域少得多，并且在动态上也造成了瓶颈，因为它们具有持续性的抑制性输出。我针对这个瓶颈提出的解决方案是，输出神经元的活动设定了一个基函数的权重，该函数由该神经元的突触连接定义。我说明了这在实际中可能是如何运作的，即允许基底神经节输出通过上丘改变皮层动力学并控制眼球运动。这个解决方案可以解释我们在理解基底神经节时遇到的棘手问题：为什么我们看到输出神经元在行为期间增加其活动，而不是像基于去抑制的理论所预测的那样只减少活动，以及为什么基底神经节的输出似乎在大脑如此小的区域内挤进了如此多的编码。
