Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
Max Planck Florida Institute for Neuroscience, Jupiter, FL, USA.
Nat Commun. 2024 Sep 11;15(1):7958. doi: 10.1038/s41467-024-51390-x.
Cortical neurons exhibit temporally irregular spiking patterns and heterogeneous firing rates. These features arise in model circuits operating in a 'fluctuation-driven regime', in which fluctuations in membrane potentials emerge from the network dynamics. However, it is still debated whether the cortex operates in such a regime. We evaluated the fluctuation-driven hypothesis by analyzing spiking and sub-threshold membrane potentials of neurons in the frontal cortex of mice performing a decision-making task. We showed that while standard fluctuation-driven models successfully account for spiking statistics, they fall short in capturing the heterogeneity in sub-threshold activity. This limitation is an inevitable outcome of bombarding single-compartment neurons with a large number of pre-synaptic inputs, thereby clamping the voltage of all neurons to more or less the same average voltage. To address this, we effectively incorporated dendritic morphology into the standard models. Inclusion of dendritic morphology in the neuronal models increased neuronal selectivity and reduced error trials, suggesting a functional role for dendrites during decision-making. Our work suggests that, during decision-making, cortical neurons in high-order cortical areas operate in a fluctuation-driven regime.
皮质神经元表现出时间上不规则的放电模式和异质性的放电率。这些特征出现在以“波动驱动”模式运行的模型电路中，其中膜电位的波动源自网络动力学。然而，皮质是否以这种模式运行仍存在争议。我们通过分析在执行决策任务的小鼠前额皮质中神经元的放电和亚阈值膜电位来评估波动驱动假说。我们表明，虽然标准的波动驱动模型成功地解释了放电统计数据，但它们在捕获亚阈值活动的异质性方面存在不足。这种局限性是用大量突触前输入轰炸单室神经元的必然结果，从而将所有神经元的电压钳制在或多或少相同的平均电压。为了解决这个问题，我们有效地将树突形态学纳入到标准模型中。在神经元模型中纳入树突形态学增加了神经元的选择性并减少了错误试验，这表明在决策过程中树突具有功能作用。我们的工作表明，在决策过程中，高级皮质区域的皮质神经元以波动驱动模式运行。
