![]() ![]() Songbirds are phylogenetically distant from humans, but they have proven a powerful model for investigating neural mechanisms underlying learned vocal behavior. However, because of the comparatively limited flexibility of vocal production in nonhuman primates ( Nieder and Mooney, 2020), the evolutionary and neural circuit mechanisms that have enabled the development of this flexibility remain poorly understood. This cognitive control over vocal production is thought to rely on the direct innervation of brainstem and midbrain vocal networks by executive control structures in the frontal cortex, which have become more elaborate over the course of primate evolution ( Hage and Nieder, 2016 Simonyan and Horwitz, 2011). Humans have unparalleled control over their vocal output, with a capacity to reorder a limited number of learned elements to produce an endless combination of vocal sequences that are appropriate for current contextual demands ( Hauser et al., 2002). The finding that they can also flexibly control vocalizations may help shed light on the interactions between cognitive processing and sophisticated vocal learning abilities.Ī crucial aspect of the evolution of human speech is the development of flexible control over learned vocalizations ( Ackermann et al., 2014 Belyk and Brown, 2017). They are one of the few animals that, like humans, learn their vocalizations by imitating conspecifics. ![]() Songbirds are an important model to study brain circuits involved in vocal learning. Moreover, birds can learn to do this ‘on command’ in response to an arbitrarily chosen signal, even if it is not something that would impact their song in nature. This suggests that songbirds can learn to flexibly and purposefully modify the way in which they sequence the notes in their songs, in a manner that parallels how humans control syllable sequencing in speech. This ability persisted for days, even without any further training. Gradually, the finches learned to modify their songs and were able to switch between the appropriate sequences as soon as the light cues changed. A specific computer program was used to detect different variations on a theme that the bird naturally produced (for example, “ab-c” versus “ab-d”), and rewarded birds for singing one sequence when the light was yellow, and the other when it was green. trained adult male Bengalese finches to change the sequence of their songs in response to random colored lights that had no natural meaning to the birds. To test whether birds can control their songs in a purposeful way, Veit et al. ![]() However, so far it was unclear whether songbirds are also capable of modifying songs independent of social or other naturally relevant contexts. Birdsongs also vary depending on their context, and melodies to seduce a mate will be different from aggressive songs to warn other males to stay away. Humans can flexibly control what they say and how by reordering a fixed set of syllables into endless combinations, an ability critical to human speech and language. Moreover, both humans and songbirds possess specific circuits in the brain that connect the forebrain to midbrain vocal centers. Both humans and birds learn their vocalizations during critical phases early in life, and both learn by imitating adults. Human speech and birdsong share numerous parallels. Our findings reveal a capacity in songbirds for learned contextual control over syllable sequencing that parallels human cognitive control over syllable sequencing in speech. Moreover, once learned, this modulation of sequencing occurs immediately following changes in contextual cues and persists without external reinforcement. ‘ab-c’ versus ‘ab-d’) in response to arbitrary visual cues. Here, we demonstrate that Bengalese finches ( Lonchura striata domestica), which sing variable syllable sequences, can learn to rapidly modify the probability of specific sequences (e.g. Based on these similarities, we hypothesized that songbirds might likewise be able to learn flexible, moment-by-moment control over vocalizations. Songbirds are phylogenetically distant from humans but share both the capacity for vocal learning and neural circuitry for vocal control that includes direct pallial-brainstem projections. The flexible control of sequential behavior is a fundamental aspect of speech, enabling endless reordering of a limited set of learned vocal elements (syllables or words). ![]()
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