Figure 7

Tutor song selectivity is elevated in single HVC neurons of formerly estrogen-suppressed adult songbirds. (A) Representative HVC single-unit recordings from an aCSF and FAD in response to presentations of birds’ own song (BOS) and tutor song. Each recording includes a song spectrogram (Top), and raster plot (Middle) with corresponding peri-stimulus time histogram in 10 ms bins (Bottom) across a 6 second period. The same unit is presented for each treatment across the two stimuli. (B) Spontaneous firing rates were similar across treatments. Orange = aCSF; blue = FAD; grey = cannula; circle = contralateral hemisphere (relative to microdialysis site); triangle = ipsilateral hemisphere (relative to microdialysis site). (C) Stimulus-evoked firing rates were significantly higher for BOS compared to all other stimuli except for TUT. Further, ipsilateral HVC displayed higher overall stimulus-evoked firing rates compared to contralateral HVC, independent of treatment. (D) Analysis of normalized auditory response (z-score) yielded similar results as with firing rate; namely, a significantly higher response to BOS over all other stimuli independent of treatment, as well as a significantly suppressed response to WN compared to CON2 and TUT. (E) Contralateral d’ values relative to CON1. TUT selectivity is significantly higher in FAD subjects solely in the contralateral hemisphere. BOS = bird’s own song; CON1; CON2 = conspecific song; REV-BOS = reverse bird’s own song; REV-TUT = reverse tutor song; TUT = tutor song. *p < 0.05.