In the last century, most sensorimotor studies of cortical neurons relied on average firing rates. Rate coding is efficient for fast sensorimotor processing that occurs within a few seconds. Much less is known about long-term working memory with a time scale of hours (Ericsson and Kintsch, 1995). The discovery of millisecond-precision spike initiation in cortical neurons was unexpected (Mainen and Sejnowski, 1995). Even more striking was the precision of spiking in vivo, in response to rapidly fluctuating sensory inputs, suggesting that neural circuits could preserve and manipulate sensory information through spike timing. High temporal resolution enables a broader range of neural codes. It could also support spike-timing-dependent plasticity (STDP), which is triggered by the relative timing of spikes between presynaptic and postsynaptic neurons in the millisecond range. What spike-timing mechanisms could regulate STDP in vivo? Cortical traveling waves have been observed across many frequency bands with high temporal precision. Traveling waves have wave fronts that could link spike timing to STDP. As a wave front passes through a cortical column, excitatory synapses on the dendrites of both pyramidal and basket cells are stimulated synchronously. Inhibitory basket cells form a calyx on pyramidal cell bodies, and inhibitory rebound following a strong transient hyperpolarization can trigger a backpropagating action potential, which arrives shortly after the excitatory inputs on pyramidal dendrites. STDP activated in this way could persist for hours, creating a second-tier network. This temporary network could support long-term working memory, a cognitive network riding above the long-term sensorimotor network. On their own, traveling waves and STDP have not yet yielded new insights into cortical function. Together, they could be responsible for how we think (Sejnowski, 2025).

翻译：上世纪，大多数关于皮层神经元的感知运动研究依赖于平均放电率。速率编码对于发生在数秒内的快速感知运动处理是高效的。然而，对于时间尺度为数小时的长时工作记忆，我们知之甚少（Ericsson and Kintsch, 1995）。皮层神经元毫秒级精度的尖峰起始的发现是出乎意料的（Mainen and Sejnowski, 1995）。更引人注目的是，在体情况下，神经元对快速波动的感觉输入产生的尖峰具有高度时序精度，这表明神经回路可能通过尖峰时序来保存和处理感觉信息。高时间分辨率使得更广泛的神经编码成为可能。它也可能支持尖峰时序依赖性可塑性（STDP），该机制由突触前和突触后神经元之间毫秒范围内的尖峰相对时序触发。哪些尖峰时序机制可以在体调节STDP？皮层行波已在多个频段被观测到，并具有高时间精度。行波具有波前，可能将尖峰时序与STDP联系起来。当波前穿过皮层柱时，锥体细胞和篮状细胞树突上的兴奋性突触被同步激活。抑制性篮状细胞在锥体细胞胞体上形成花萼样结构，强烈的瞬时超极化之后的抑制性反弹可以触发一个反向传播的动作电位，该电位在锥体细胞树突上的兴奋性输入之后不久到达。以此方式激活的STDP可以持续数小时，形成一个次级网络。这个临时网络可以支持长时工作记忆，这是一个运行在长时感知运动网络之上的认知网络。单独来看，行波和STDP尚未为皮层功能带来新的洞见。但两者结合，可能正是我们思考方式的成因（Sejnowski, 2025）。