Fig. 3. Catecholamine-induced increase in E/I ratio can increase perceptual variability.

(A) Effect of atomoxetine on rate of transitions in the judgment of continuous input (changes in the apparent direction of rotation of the seemingly rotating sphere). **P < 0.01 (two-sided paired permutation test). (B) Left: Schematic of the decision circuit, endowed with two excitatory decision populations, D1 and D2, and a nonselective population (DN), fully connected to a pool of inhibitory neurons. The two decision populations receive equally strong, noisy Poisson input, reflecting the ambiguous nature of the visual stimulus. Right: The model exhibits spontaneous firing rate fluctuations. Perceptual transitions in the model are defined as changes in the dominance of one population over the other (i.e., one having a higher firing than the other). (C) Effect of E/I increase in circuit model on number of transitions in the judgment of continuous input. E/I increase in the circuit model is implemented via decrease in feedback inhibition (red/blue arrows).