Cortico-Thalamic Circuit Model for Bottom-Up and Top-Down Mechanisms in General Anesthesia Involving the Reticular Activating System

General anesthesia is a widely used medical procedure. However, its underlying physiological mechanisms are still unknown. Cur-rent research has identified bottom-up mechanisms in the brain involving subcortical sleep-promoting and arousal structures and top-down mechanisms comprising corticocortical and corticothalamic circuits. The current work presents a neural model consider-ing both mechanisms. Its numerical simulation yields frontal and occipital cortical activity that exhibits the characteristic spectral changes as observed experimentally. In addition, increasing the anesthetic level enhances local synchrony and weakens distant synchrony. This represents a fragmentation of the brain as observed in experimental data under anesthesia.