Fig. 2.
Consequences of decreasing similarity between BOS and tutor song. A, When a juvenile stores a good copy of the tutor song (A) as its template (A) and accurately models its own song after the template, the resulting BOS (A) will highly resemble the tutor song. Thus, if a neuron is tuned by BOS experience only, it could also respond well to tutor song when the two songs are similar enough. This ambiguity could be resolved by making the BOS very different (B) from the tutor song.B, Decreasing the similarity between BOS and tutor song has two predicted outcomes on the distribution ofd′BOS–tutor values. If BOS experience shapes some neurons, and tutor song experience shapes others, then the distribution should be split in two, with some neurons preferring tsBOS over tutor song and others preferring tutor over tsBOS but none responding equally well to both (solid line). Alternatively, if both tsBOS and tutor song influence the neural properties of single neurons, then neurons with equivalent responses should persist (dotted line). C, If a poor copy of the tutor song (A) is stored as the template (a) and then a good copy of the template is produced, then the resulting BOS (a) is a better model of the template than the tutor song itself. In this case, neurons preferring BOS would nonetheless reflect tutor song experience. Inducing an abnormal BOS by disrupting sensorimotor learning (B) should decrease the similarity between BOS and a song resulting from poor memorization of the tutor song.