Studies on central nervous mechanisms of vocalization in monkeys

用电极长期植入猴体表和皮层各区域2.0 ~ 3.0mm深度，记录自定速发声训练猴的场电位。在3只猴子中，发声前的表面负、深度正（s-N、d-P）慢电位由两个半球的前运动皮质、运动皮质和体感觉皮质以及辅助运动区引导。当猴子带着强烈的奖励动机发声时，这种运动前电位也被记录在扣带皮层和前额叶皮层。右侧小脑半球切除术消除了左半球运动皮层和弓状沟（Broca’s同源物）下肢后侧的s-N、d-P运动前电位。手术后，音调中不同频率的分量减少了，持续时间的变化也比以前大了很多。这些事实表明，与人类语言同源的新皮质区可能通过脑-小脑相互作用与小脑一起参与猴子发声的产生和控制。这与迄今为止提出的关于非人灵长类动物发声的观点相悖，即通常认为动物发声与人类言语有根本区别。猴子也接受了足够的训练，在三个多月的时间里，它们会对猴子发出的低叫声做出回应（由声音发起的叫声）。用上述电极记录声音诱发发声的场电位，并测量从刺激开始到发声开始的反应时间。在刺激后约70 ms的潜伏期，在左脑弓状沟下肢前岸记录到s-N、d-P电位，而在自节奏发声时未记录到明显的电位。在运动和体感觉皮层，在潜伏期约300 ms时记录s-N、d-P电位。与之前报道的由音频引导的手部动作相比，反应时间明显更长，变化也更大。Gemba & Sasaki, Exp.Brain Res. (1987) 65: 649-657

Field potentials were recorded with electrodes chronically implanted on the surface and at 2.0-3.0mm depth in various cortical areas in monkeys trained for vocalizing at self-pace (self-paced vocalization). In three monkeys, surface-negative, depth-positive (s-N,d-P) slow potentials prior to vocalization were led from the premotor, motor and somatosensory cortices and supplementary motor area in both hemispheres. Such premovement potentials were recorded also in the cingulate and prefrontal cortices when a monkey vocalized with strong motivation for reward. Cerebellar hemispherectomy on the right side eliminated the s-N,d-P premovement potentials in the motor cortex and in the posterior bank of the inferior limb of the arcuate sulcus (Broca's homologue) in the left hemisphere. After the operation, the tone came to have less components of different frequencies, and its duration varied much more than before. These facts suggest that the neocortical area homologous to the human speech are … More a takes part in the generation and control of monkey vocalization together with the cerebellum possibly through cerebro-cerebellar interactions. This is against ideas so far proposed on nonhuman primate vocalization, i.e., it is generally considered that animal vocalization differs fundamentally from human speech.Monkeys were also enough trained to vocalize in response to auditory stimulus of a monkey's coo vocalization for more than three months (audio-initiated vocalization). Field potentials on the audio-initiated vocalization were recorded with the electrodes described above, and reaction times were measured from the onset of stimulus to the start of vocalization. A s-N,d-P potential was recorded at a latency of about 70 ms after the stimulus in the anterior bank of the inferior limb of the arcuate sulcus in the left hemisphere in which no significant potential was recorded on self-paced vocalization. In the motor and somatosensory cortices, s-N,d-P potentials were recorded at a latency of about 300 ms. Reaction times were obviously longer and more variable when compared with the audio-initiated hand movements^1 reported before.1.Gemba & Sasaki, Exp.Brain Res. (1987) 65 : 649-657 Less