Figure 7.

Estimated neuronal activity. These plots show the estimated activity in each excitatory cell population. Dashed lines indicate the superficial pyramidal cells that give rise to ascending connections and are inhibited by higher cortical sources. Ascending connections target the spiny stellate cells (dotted lines), and the deep pyramidal cells (unbroken lines). The latter give rise to descending connections. The activity here is shown for early (blue) and late (red) cancellations, for each of the cortical areas shown in Figure 5. The bottom left plot (highlighted) shows the simulated evoked responses obtained from the Markov decision-process model described by Parr and Friston (2017b), drawing from the process theory associated with active inference (Friston et al., 2016). It is computed by taking the absolute rate of change of the sufficient statistics of posterior beliefs about the current fixation location, summed over spatial scales (please see the discussion for details). Whereas the y-axis here is arbitrary, the x-axis extends to 250 ms, consistent with the theta frequency of saccadic eye movements. There is a striking resemblance between the simulated rate of belief updating and the FEF neuronal activity estimated from our empirical data.