Simulated depolarizing currents (red colours) significantly increased choice stochasiticity (i.e., increased
inverse temperature). ( A) and % correct choices ( B). Furthermore, they increased the difference between the pre-stimulus firing rates of the pyramidal populations ( C) as well as in interneurons ( D). Alternative simulations (Altern. 1–2) varying the impact on inhibitory interneurons revealed that these observations were relatively robust to changes in membrane potentials of interneurons. By contrast, no comparable physiological or behavioural change was observed when omitting current to the pyramidal neurons (Depolar. Altern. 3), as expected given current knowledge on how polarizing currents affect pyramidal neurons. Simulated hyperpolarizing currents (green colours) slightly decreased choice stochasticity (i.e., increased inverse temperature) ( A) and thus increased choice accuracy ( B), and reduced the difference between the pre-stimulus firing rates of the pyramidal populations ( C) as well as in interneurons ( D). Similar to depolarizing currents, for hyperpolarizing currents these effects were relatively robust with regards to the specific changes in membrane potentials applied to inhibitory interneurons (Altern. 1–2), but became indistinguishable from baseline (control; blue) simulations when omitting current to the pyramidal neurons (Hyperpolar. Altern. 3). Error bars indicate 1 SEM, asterisks indicate reliable condition differences at p < 0.05 (Bonferroni corrected).