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. Author manuscript; available in PMC: 2019 Apr 4.
Published in final edited form as: Neuron. 2018 Mar 15;98(1):208–221.e5. doi: 10.1016/j.neuron.2018.02.020

Figure 1. Pitch contingent auditory feedback guides pitch learning.

Figure 1

A) Schematic of experimental design for close-looped pitch-contingent auditory feedback. B) Sonogram from the bird used in the pCAF experiment illustrated in figures 1C – 1D. White noise (WN) bursts were delivered over syllable ‘d’ during lower pitch variants. ‘iabbcd’ indicate the syllables that comprise the bird’s motif and the introductory syllable. Arrowhead indicates a 5ms segment where the pitch of target syllable ‘d’ was measured; black box indicates target syllable; red line marks 100ms playback of white-noise. C) Plot of the pitch of syllable ‘d’ across 1,500 motifs before and during pCAF, each point corresponds to one rendition of the syllable. Closed-loop targeting of WN to lower pitch variants (red dots, ‘hit’) but not higher pitch variants (black dots, ‘escape’) resulted in an increase in the number ‘escape’ of trials . D) Plot of the running average of the pitch and hit rate (contingency) during the day of closed-loop pCAF illustrates the rapid increases in running average of pitch (black line) and concomitant decreases in contingency percentage (red line). Each point corresponds to a single syllable rendition and shaded region indicates ± one standard deviation; gray box indicates the baseline period before WN was delivered. E) Changes in running average of pitch during baseline day (open) and WN day (filled) in 7 birds in which WN was delivered to lower pitch variants (downward pointing triangles). WN delivering elicited increases in the running average of pitch (p=0.016, n=7, Wilcoxon matched-pairs signed-rank test). F) Changes in contingency percentage during baseline day (open) and WN day (filled) in 7 birds in which WN was delivered to lower pitch variants. WN elicited decreases in the contingency (p=0.015, n=7, Wilcoxon matched-pairs signed-rank test). G) Hypothetical source of instructive signal in natural pitch learning. H) General hypothesis tested in this paper: phasic increases and decreases in VTA neurons projecting to Area X encode positive and negative reinforcement signals that are each sufficient to guide song learning.