Fig. 10.

Illustration of a labeled-line model.A, Each event produces short-lasting excitation and long-lasting inhibition followed by rebound excitation. Neither the excitation nor rebound from inhibition is capable of eliciting a suprathreshold response. If excitation from a second event coincides with rebound from the first event, threshold is reached. By adjusting the duration of inhibition (or equivalently the strength) it is possible to have labeled lines for a range of intervals.B, In the case of two stimuli composed of sequence of three pulses (each composed of a 100 and 200 msec interval), both stimuli will activate the same interval detectors, albeit in a different order. Thus, sequence discrimination will require subsequent order discrimination. One problem this type of model has with sequence discrimination is that for the appropriate labeled-line to detect the second interval, each pulse would have to “reset” the interval detector (dashed lines).