Thinking outside the cortex: social motivation in the evolution and development of language

Abstract

Alteration of the organization of social and motivational neuroanatomical circuitry must have been an essential step in the evolution of human language. Development of vocal communication across species, particularly birdsong, and new research on the neural organization and evolution of social and motivational circuitry, together suggest that human language is the result of an obligatory link of a powerful cortico-striatal learning system, and subcortical socio-motivational circuitry.

The Role of Reward in Word Learning and Its Implications for Language Acquisition

“…It has been proposed at the theoretical level that an anatomical link between subcortical reward mechanisms and cortical learning systems might be essential to the development of language and communication [1]. Extending this rationale to the level of functional neuroanatomy, we hypothesized that human adults would show enhanced activity within subcortical reward and motivational circuitries when successfully learning new words.…”

“…Moreover, this motivation to learn is preserved throughout the lifespan, helping adults to acquire a second language [6,7]. However, the exact mechanism behind the human drive to acquire communicative linguistic skills is yet to be established [8,9].It has been proposed at the theoretical level that an anatomical link between subcortical reward mechanisms and cortical learning systems might be essential to the development of language and communication [1]. Extending this rationale to the level of functional neuroanatomy, we hypothesized that human adults would show enhanced activity within subcortical reward and motivational circuitries when successfully learning new words.…”

“…Recent theoretical models have proposed that during human evolution, emerging language-learning mechanisms might have been glued to phylogenetically older subcortical reward systems [1], reinforcing human motivation to learn a new language. Supporting this hypothesis, our results showed that adult participants exhibited robust fMRI activation in the ventral striatum (VS)-a core region of reward processing [2]-when successfully learning the meaning of new words.…”

Convergent Evolution of Vocal Cooperation without Convergent Evolution of Brain Size

“…There is a large overlap in structures considered to underlie social behavior (and vocal behavior, in particular) as well as those underlying motivation and emotional arousal [Cardinal et al, 2002;Syal and Finlay, 2011]. The shared neural architecture enables a pathway in which social interaction is 'rewarded' via the attachment of motivational value through arousal levels [Syal and Finlay, 2011].…”

“…The shared neural architecture enables a pathway in which social interaction is 'rewarded' via the attachment of motivational value through arousal levels [Syal and Finlay, 2011]. That is, fluctuating arousal levels could be a driving factor in vocal turn taking.…”