Dipartimento di Neuroscienze, Università di Parma, Parma, Italy.
PLoS One. 2011;6(11):e26822. doi: 10.1371/journal.pone.0026822. Epub 2011 Nov 2.
The voluntary control of phonation is a crucial achievement in the evolution of speech. In humans, ventral premotor cortex (PMv) and Broca's area are known to be involved in voluntary phonation. In contrast, no neurophysiological data are available about the role of the oro-facial sector of nonhuman primates PMv in this function. In order to address this issue, we recorded PMv neurons from two monkeys trained to emit coo-calls. Results showed that a population of motor neurons specifically fire during vocalization. About two thirds of them discharged before sound onset, while the remaining were time-locked with it. The response of vocalization-selective neurons was present only during conditioned (voluntary) but not spontaneous (emotional) sound emission. These data suggest that the control of vocal production exerted by PMv neurons constitutes a newly emerging property in the monkey lineage, shedding light on the evolution of phonation-based communication from a nonhuman primate species.
发声的随意控制是语言进化的一个关键成就。在人类中，腹侧运动前皮质（PMv）和布罗卡区被认为参与了发声的随意控制。相比之下，关于非人类灵长类动物 PMv 的口面部区域在这个功能中的作用，还没有神经生理学数据。为了解决这个问题，我们记录了两只经过训练发出咕咕叫声的猴子的 PMv 神经元。结果表明，一群运动神经元专门在发声时放电。大约三分之二的神经元在声音发出前放电，而其余的则与声音同步。发声选择神经元的反应仅在条件反射（随意）声音发射期间出现，而不在自发（情绪）声音发射期间出现。这些数据表明，PMv 神经元对发声产生的控制构成了猴类谱系中新出现的特性，为从非人类灵长类物种的语音交际进化提供了新的视角。
