Innate vs. Learned Vocalization

Every mammal and many other animals possess a larynx with the potential for making sounds. In communication, these regions serve to transmit information that will influence the listener’s behavior, i.e. to attract, fend off, inform, or warn (Bright, 1984). Among these many types of sounds, some animals appear able to produce more complex, learned vocalizations, while most are limited to rudimentary, innate vocalizations (Jarvis, 2004)

The distinction between innate versus learned vocalization is not completely rigid, but there do appear to be linguistic and neuroanatomical distinctions separating them. Linguistically, learned vocalizations are often synonymous with greater communicative variation and flexibility, whereas non-learned vocalizations are not. Thus, very basic forms of squalling, ultrasonic pipping, ultrasonic whistling, coughing, snorting, and growling, appear to be common among most animals capable of non-learned vocalization, such as the South American Tapir, panda, mice, birds, and others (Jarvis, 2004; Gaub et al., 2010). Some innate vocalizations among the more agonistic sounds, such as growling and roaring, appear to be widespread among many mammals, and are unrelated to body size, habitat or laryngeal structure (Jarvis, 2006).

Beyond these basic, innate forms of vocalization, vocal learners but not vocal non-learners tend to produce more varied frequency modulation and syntax (Okanoya, 2002). There appear to be a select few species that are capable of learned vocalization. These include the parrot, hummingbird, and songbird on one hand, and humans, bats, cetaceans, and elephants on the other (Jarvis, 2006). Interestingly, each of these vocal learners appear to be the top of their predatory chai...

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...urs in the face motor cortex (Gracco et al., 2005). Moreover, activation in Broca’s, dlPFC, aSMA is higher when speech tasks are more complex, including learning to vocalize new words or sentences, complex syntax, etc. (Buckner et al., 1999). In addition, low threshold electrical stimulation to the face motor cortex, Broca’s or the aSMA cause speech arrest or generation of phonemes or words (Ojemann, 1991). Low threshold electrical stimulation to ventral lateral and anterior thalamic nuclei, particularly in the left hemisphere, leads to word repetition, speech arrest, speech acceleration, spontaneous speech, or verbal aphasia (Johnson and Ojemann, 2000). Finally, song learning in humans is accompanied by higher activation of the anterior premotor cortical and striatal regions relative to simply production of already well-learned songs (Brown et al., 2006).