Elevations in brain serotonin, caused by genetic or pharmacological interference with the serotonin transporter, enhances reversal learning performance,125–128 and variation in the serotonin transporter gene influences inhibitory control during reversal learning in monkeys.129, 130 At least with respect to reversal learning, antagonism of serotonin-2C receptor enhances the ability of rats to learn a spatial reversal task,131, 132 an effect mediated by the orbitofrontal cortex,133 while blockade of serotonin-2A receptors impairs reversal performance.131
