Figure 4.

A, Example spectrograms before (top) and after (bottom) 5-HT lesion surgery. Song was left largely intact. B, Mean frequency of syllables was significantly reduced 2 weeks after lesion (days 13–15, p = 0.0026, Δ −178.7 ± 29.32 Hz, n = 5 animals per group). C, The change in mean frequency at 2 weeks postlesion was significantly related to the amount of 5-HT in RA measured the following day (p = 0.0082, R² = 0.6032). Closed circles represent lesioned animals, open circles represent controls. Each data point in B and C corresponds to the mean of syllables for one animal, with each syllable type sorted and analyzed separately.