الضجيج الحراري يفرض حداً على الإشارات العصبية سريع

الملخص الأصلي

كما كتبه المؤلفون، بالإنجليزية arXiv:2604.03538

Voltage-gated ion channels are essential for propagating signals in neurons. Each channel senses the local membrane potential created by nearby ions. Fluctuations in these ions introduce two fundamental noise sources: (i) shot noise, from the discreteness of ionic charge, and (ii) Johnson-Nyquist noise, from long-wavelength thermal fluctuations of the electric field. We show that, for an individual channel, shot noise dominates and sets an intrinsic limit to voltage sensing. On the $$10$$ $$\mu$$s timescales relevant to channel gating, this limit corresponds to an accuracy of about $$10$$ mV -- close to measured channel sensitivities. When signals from many channels are aggregated, Johnson-Nyquist noise eventually overtakes shot noise and bounds the total information that can be sensed from the environment. This transition occurs at an ion channel density of $$< 1$$ channel/$$\mu$$m$$^2$$ for slow signals and around $$10^2-10^4$$ channels/$$\mu$$m$$^2$$ for signals with $$10$$ $$\mu$$s timescales, both of which are within the range of experimentally-measured densities for somas and axon initial segments, respectively. These results provide design principles for single-channel architecture and collective sensing and suggest that neuronal computation is ultimately constrained by thermal fluctuations.