Ongoing Spontaneous Activity Controls Access to Consciousness: A Neuronal Model for Inattentional Blindness
Figure 4
A Comparison of Spontaneous and Evoked Global Ignition in the Workspace Model
Each tracing shows the temporal evolution of the LFP (bottom trace) and spikes (top trace) in one area of the model over a 1-s period, with Ineuromodul = −1.0 μA/cm2. In the two sets of tracings on the left, within an interval characterized by spontaneous membrane oscillations and low spike rates, the neurons coding for assembly 2 become spontaneously activated at an elevated rate for a period of 200–300 ms. The arrows mark the approximate onset of activation, which starts earlier from the higher areas D2 and C2, with a concomitant inhibition of spontaneous activity in areas D1 and C2. In the two sets of tracings on the right, the same network was stimulated by stimulus 2 at the time marked by the arrow. Note that activation now starts by a bottom-up propagation from areas A2 to D2, followed by top-down amplification in the reverse direction. This two-step process creates a characteristic firing profile with two successive peaks, particularly visible in area A2.