Poremba Amy, Malloy Megan, Saunders Richard C, Carson Richard E, Herscovitch Peter, Mishkin Mortimer
Behavioral and Cognitive Neuroscience, Department of Psychology, University of Iowa, Iowa City, Iowa 52242, USA.
Nature. 2004 Jan 29;427(6973):448-51. doi: 10.1038/nature02268.
It has often been proposed that the vocal calls of monkeys are precursors of human speech, in part because they provide critical information to other members of the species who rely on them for survival and social interactions. Both behavioural and lesion studies suggest that monkeys, like humans, use the auditory system of the left hemisphere preferentially to process vocalizations. To investigate the pattern of neural activity that might underlie this particular form of functional asymmetry in monkeys, we measured local cerebral metabolic activity while the animals listened passively to species-specific calls compared with a variety of other classes of sound. Within the superior temporal gyrus, significantly greater metabolic activity occurred on the left side than on the right, only in the region of the temporal pole and only in response to monkey calls. This functional asymmetry was absent when these regions were separated by forebrain commissurotomy, suggesting that the perception of vocalizations elicits concurrent interhemispheric interactions that focus the auditory processing within a specialized area of one hemisphere.
人们常常认为，猴子的叫声是人类语言的前身，部分原因在于它们能为该物种的其他成员提供关键信息，而这些成员依靠这些信息生存和进行社交互动。行为学和损伤研究均表明，猴子和人类一样，优先使用左半球的听觉系统来处理发声。为了探究这种猴子特有的功能不对称形式背后的神经活动模式，我们在动物被动聆听特定物种叫声以及其他各类声音时，测量了局部脑代谢活动。在颞上回内，仅在颞极区域，且仅对猴子叫声产生反应时，左侧的代谢活动显著高于右侧。当这些区域通过大脑前连合切开术分隔开时，这种功能不对称就消失了，这表明发声感知会引发同时性的半球间相互作用，从而将听觉处理集中在一个半球的特定区域内。
