Left, neurons in group A; right, neurons in group B. Three trials are displayed with the signal’s coherence c?? 0% (bottom), 12.8% (middle), and 51.2% (top). In all three cases, the attractor A wins the competition and therefore the network’s choice is said to be A (correct decision for c?? 0%). Similar to the neural data from LIP, there is a slow time course of activity in group A, with the ramping slope increasing with the signal strength. Moreover, even when the coherence is zero, the firing patterns of the two neural groups diverge dramatically over time during the stimulation, leading to a categorical (binary) decision formed by the network. The inhibitory population, which does not receive direct stimulation but is recruited by pyramidal cells, also shows ramping activity (bottom), and the winner-take-all competition results from this feedback inhibition. Finally, the persistent activity in group A during the mnemonic delay period, with a level independent of the stimulus strength, stores the short-term memory of the decision choice.