English: Figure 3. Mechanisms of sequence generation in the adult song motor pathway. Illustration of the hypothesis that RA-projecting HVC (HVC(RA)) neurons burst and activate each other sequentially in groups of 100 to 200 coactive neurons. Each group of HVC neurons drives a distinct ensemble of RA neurons to burst. The neurons converge with some effective weight at the level of the motor neurons to activate syringeal muscles.