Acetylcholine optimizes sensory coding by tuning criticality in a clustered neural network

Understanding the principles governing efficient information processing in biological neural systems requires the identification of mechanisms for the flexible integration of external sensory signals and internal spontaneous activity. Neural systems operating near criticality exhibit optimized sensitivity and reliability in processing sensory signals. We hypothesize acetylcholine (ACh), a key neuromodulator, controls the sensory speed in neural systems by modulating critical dynamics. Using a computational model based on an ACh-modulated clustered network, our simulations reveal a U-shaped relationship between ACh concentration and sensory response latency, with the fastest responses occurring near a phase transition. At this critical point, the model exhibits intermittent bursts of cluster activity characterized by irregular periods. This critical dynamics allows the network to flexibly and simultaneously combine different cluster activities, facilitating the classification of diverse sensory inputs. Basing on network theory and statistical analysis, we propose that ACh maintains neural criticality by balancing synchronization and stability. This work presents a theory connecting neuromodulation to critical dynamics, with implications for perception and the development of efficient brain-inspired computing.