Birds, primates, and spoken language origins: Behavioral phenotypes and neurobiological substrates

Institute of Neuroscience, Newcastle University Newcastle upon Tyne, UK.
Frontiers in Evolutionary Neuroscience 08/2012; 4:12. DOI: 10.3389/fnevo.2012.00012
Source: PubMed


Vocal learners such as humans and songbirds can learn to produce elaborate patterns of structurally organized vocalizations, whereas many other vertebrates such as non-human primates and most other bird groups either cannot or do so to a very limited degree. To explain the similarities among humans and vocal-learning birds and the differences with other species, various theories have been proposed. One set of theories are motor theories, which underscore the role of the motor system as an evolutionary substrate for vocal production learning. For instance, the motor theory of speech and song perception proposes enhanced auditory perceptual learning of speech in humans and song in birds, which suggests a considerable level of neurobiological specialization. Another, a motor theory of vocal learning origin, proposes that the brain pathways that control the learning and production of song and speech were derived from adjacent motor brain pathways. Another set of theories are cognitive theories, which address the interface between cognition and the auditory-vocal domains to support language learning in humans. Here we critically review the behavioral and neurobiological evidence for parallels and differences between the so-called vocal learners and vocal non-learners in the context of motor and cognitive theories. In doing so, we note that behaviorally vocal-production learning abilities are more distributed than categorical, as are the auditory-learning abilities of animals. We propose testable hypotheses on the extent of the specializations and cross-species correspondences suggested by motor and cognitive theories. We believe that determining how spoken language evolved is likely to become clearer with concerted efforts in testing comparative data from many non-human animal species.

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    • ", 2014 ) . The songbird HVC is similar to layers 2 and 3 neurons of primary motor cortex , and thereby possibly also to LMC ; songbird LMAN has a weak similarity to Broca ' s area that requires further investigation for confirmation ; DLM ( dorsolateral nucleus of the medial thalamus ) is most similar to the human anterior thalamus necessary for speech learning and production ( Jarvis , 2004 ; Petkov and Jarvis , 2012 ) . In this article I present a hypothesis on how foreign accents could be improved by optimizing variability in vocal learning brain circuits , followed by support for the hypothesis , drawing on the literature on variability in songbird vocal learning and variability in motor learning . "
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    ABSTRACT: Rapid vocal motor learning is observed when acquiring a language in early childhood, or learning to speak another language later in life. Accurate pronunciation is one of the hardest things for late learners to master and they are almost always left with a non-native accent. Here, I propose a novel hypothesis that this accent could be improved by optimizing variability in vocal learning brain circuits during learning. Much of the neurobiology of human vocal motor learning has been inferred from studies on songbirds. Jarvis (2004) proposed the hypothesis that as in songbirds there are two pathways in humans: one for learning speech (the striatal vocal learning pathway), and one for production of previously learnt speech (the motor pathway). Learning new motor sequences necessary for accurate non-native pronunciation is challenging and I argue that in late learners of a foreign language the vocal learning pathway becomes inactive prematurely. The motor pathway is engaged once again and learners maintain their original native motor patterns for producing speech, resulting in speaking with a foreign accent. Further, I argue that variability in neural activity within vocal motor circuitry generates vocal variability that supports accurate non-native pronunciation. Recent theoretical and experimental work on motor learning suggests that variability in the motor movement is necessary for the development of expertise. I propose that there is little trial-by-trial variability when using the motor pathway. When using the vocal learning pathway variability gradually increases, reflecting an exploratory phase in which learners try out different ways of pronouncing words, before decreasing and stabilizing once the “best” performance has been identified. The hypothesis proposed here could be tested using behavioral interventions that optimize variability and engage the vocal learning pathway for longer, with the prediction that this would allow learners to develop new motor patterns that result in more native-like pronunciation.
    Frontiers in Human Neuroscience 11/2015; 9. DOI:10.3389/fnhum.2015.00606 · 3.63 Impact Factor
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    • "Future behavioral research should test perception of different coordination patterns across species . Building on behavioral results , the long term goal will be to uncover the neuro - ( epi ) genetics ( Lachmann and Jablonka , 1996 ; Petkov and Jarvis , 2012 ; Bronfman et al . , 2014 ; Wilkins et al . "

    Frontiers in Neuroscience 09/2015; 9. DOI:10.3389/fnins.2015.00339 · 3.66 Impact Factor
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    • "We decided to investigate the early development of the zebra finch (hereafter referred to as the finch) in more detail. The finches are a model system commonly used in neurobiological studies of social behavior (Brazas and Shimizu, 2002; Svec et al., 2009), vocalization, and learning (Jarvis, 2004; Petkov and Jarvis, 2012). These studies have led to an eLife digest In animals, stem cells divide to give rise to other cells that have specialized roles in the body. "
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    ABSTRACT: Innate pluripotency of mouse embryos transits from naïve to primed state as the inner cell mass (ICM) differentiates into epiblast. In vitro, their counterparts are embryonic (ESCs) and epiblast stem cells (EpiSCs) respectively. Activation of the FGF signalling cascade results in mouse ESCs differentiating into mEpiSCs, indicative of its requirement in the shift between these states. However, only mouse ESCs correspond to the naïve state; ESCs from other mammals and from chick show primed state characteristics. Thus, the significance of the naïve state is unclear. Here, we use zebra finch as a model for comparative ESC studies. The finch blastoderm has mESC-like properties, while chick blastoderm exhibits EpiSC features. In the absence of FGF signalling, finch cells retained expression of pluripotent markers, which were lost in cells from chick or aged finch epiblasts. Our data suggest that the naïve state of pluripotency is evolutionarily conserved among amniotes.
    eLife Sciences 09/2015; 4. DOI:10.7554/eLife.07178 · 9.32 Impact Factor
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