John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138.
Center for Brain Science, Harvard University, Cambridge, MA 02138.
Proc Natl Acad Sci U S A. 2024 Aug 6;121(32):e2309876121. doi: 10.1073/pnas.2309876121. Epub 2024 Jul 30.
Understanding how neural circuits generate sequential activity is a longstanding challenge. While foundational theoretical models have shown how sequences can be stored as memories in neural networks with Hebbian plasticity rules, these models considered only a narrow range of Hebbian rules. Here, we introduce a model for arbitrary Hebbian plasticity rules, capturing the diversity of spike-timing-dependent synaptic plasticity seen in experiments, and show how the choice of these rules and of neural activity patterns influences sequence memory formation and retrieval. In particular, we derive a general theory that predicts the tempo of sequence replay. This theory lays a foundation for explaining how cortical tutor signals might give rise to motor actions that eventually become "automatic." Our theory also captures the impact of changing the tempo of the tutor signal. Beyond shedding light on biological circuits, this theory has relevance in artificial intelligence by laying a foundation for frameworks whereby slow and computationally expensive deliberation can be stored as memories and eventually replaced by inexpensive recall.
理解神经回路如何产生序列活动是一个长期存在的挑战。虽然基础理论模型已经表明,序列可以作为具有赫布氏可塑性规则的神经网络中的记忆存储,但这些模型仅考虑了窄范围的赫布氏规则。在这里,我们引入了一个用于任意赫布氏可塑性规则的模型,该模型捕获了实验中所见的各种尖峰时间依赖性突触可塑性,并展示了这些规则和神经活动模式的选择如何影响序列记忆的形成和检索。特别是,我们推导出了一个可以预测序列重放节奏的一般理论。该理论为解释皮质导师信号如何产生最终变得“自动”的运动动作奠定了基础。我们的理论还捕捉到了改变导师信号节奏的影响。除了阐明生物电路之外,该理论在人工智能中具有相关性,为框架奠定了基础,通过该框架,可以将缓慢且计算成本高的思考存储为记忆,并最终通过廉价的回忆来取代。