Fig. 1.

Equations of motion for a single source. This schematic summarizes the equations of motion or state equations that specify a Jansen and Rit (1995) neural mass model of a single source. This model contains three populations, each loosely associated with a specific cortical layer. The second-order differential equations describe changes in hidden states (e.g., voltage) that subtend observed local field potentials or EEG signals. These differential equations effectively mediate a linear convolution of presynaptic activity to produce postsynaptic depolarization. Average firing rates within each sub-population are then transformed through a nonlinear (sigmoid) voltage-firing rate function σ(⋅) to provide inputs to other populations. These inputs are weighted by connection strengths.