Push-Pull Network Effects of Brain Oscillatory Activity in Disorders of Consciousness

Enhanced low-frequency oscillations in the delta band (1–4 Hz) are thought to be a pathological neurological phenomenon of disorders of consciousness (DOC), which can be effectively suppressed by introducing high-frequency cortical stimulation (CS) into the thalamocortical network. However, the pathophysiological mechanism of DOC remains unclear. Therefore, the present work provides a mathematical model that can elaborate on the possible mechanisms of abnormal oscillation generation and inhibition in the thalamus-cortex circuit. Describing function analysis is used to visualize the push-pull effects of CS on DOC oscillations. Simulation results show that reducing the synaptic action of excitatory interneurons on pyramidal neurons pushes the thalamocortical network into a pathological low-frequency (delta band) oscillatory state, manifested by the intersection of the Nyquist curve with the negative inverse curve of the describing function. Conversely, the separation of these two curves illustrates the role of CS, which pulls the thalamocortical network out of abnormal oscillations. This work provides a new perspective on the push-pull network mechanism of CS and the prediction of effective stimulation parameters.