to preferred directions of whisker deflection, excitation precedes inhibition in barrel cortex but the temporal delay between the two synaptic conductances is reduced in response to nonpreferred stimuli (Wilent and Contreras, 2005). Similarly, in neurons of auditory cortex that are tuned to sound intensity, the temporal delay of inhibition relative to excitation becomes smaller as tone intensity increases resulting in a sharpening of intensity tuning (Wu et al., 2006). Thus, stimulus selectivity in the cortex can emerge from a temporal shift in the timing of excitation relative to inhibition.
