recent data from S-carrier monkeys (88) and 5-HTT mutant mice (91) demonstrating that reversal learning, a measure of cognitive flexibility subserved by the orbitofrontal cortex (92), is enhanced as a function of relative 5-HTT gene deficiency. This may reflect increased sensitivity to negative environmental stimuli, although further work will be needed to substantiate this. Notwithstanding, these data indicate that altered 5-HTT gene function may influence multiple higher behaviors, as would be predicted if it affects a core corticolimbic neural circuitry.
