Watanabe M
Department of Liberal Arts, Tokyo Engineering University, Japan.
Exp Brain Res. 1992;89(2):233-47. doi: 10.1007/BF00228241.
Two monkeys were trained on both visual and auditory association tasks. Single unit activity of the frontal (prefrontal and post-arcuate premotor) cortex was recorded in these monkeys to investigate the convergence of visual and auditory inputs and to examine whether the frontal units are involved in coding the meaning (associative significance) of the stimulus, independent of its modality. A total of 289 units showed changes in firing rate after the cue presentation on the visual and/or auditory tasks and were examined on both modalities of tasks, 175 of them showing differential activity in relation to either the associative significance and/or physical properties of the visual and/or auditory cues. Of the 289 units, 136 (47.0%) were responsive only to the visual cue (76 of them showing cue-related differential activity), 13 units (4.5%) only to the auditory cue (6 of them showing cue-related differential activity) and the remaining 140 units (48.5%) to both modalities of cues (18 of them showing visual, 7 of them showing auditory and 68 showing both modalities of cue-related differential activity). Fifty of the 68 bimodal differential units showed changes in firing in relation to the associative significance of both modalities of cues independent of the cue's physical properties, and are considered to be involved in the crossmodal coding of the associative significance of the stimulus. The proportion of bimodal differential units was higher in the pre- and post-arcuate areas than in the principalis and inferior convexity areas of the frontal cortex. The results indicate that some frontal units participate in the crossmodal coding of the associative significance of the stimulus independent of its physical properties, and most frontal units play different roles depending on the modality of the stimulus.
对两只猴子进行了视觉和听觉联想任务的训练。记录这些猴子额叶（前额叶和弓状后运动前区）皮质的单个神经元活动，以研究视觉和听觉输入的汇聚情况，并检查额叶神经元是否参与对刺激意义（联想显著性）的编码，而不考虑其模态。共有289个神经元在视觉和/或听觉任务的提示呈现后放电率发生变化，并在两种任务模态上进行了检查，其中175个神经元在与视觉和/或听觉提示的联想显著性和/或物理属性相关的活动上表现出差异。在这289个神经元中，136个（47.0%）仅对视觉提示有反应（其中76个表现出与提示相关的差异活动），13个（4.5%）仅对听觉提示有反应（其中6个表现出与提示相关的差异活动），其余140个神经元（48.5%）对两种模态的提示都有反应（其中18个表现出视觉、7个表现出听觉、68个表现出两种模态的与提示相关的差异活动）。68个双模态差异神经元中有50个在与两种模态提示的联想显著性相关的放电方面发生变化，而与提示的物理属性无关，被认为参与了刺激联想显著性的跨模态编码。双模态差异神经元在前弓状和后弓状区域的比例高于额叶皮质的主要区域和下凸区域。结果表明，一些额叶神经元参与了与刺激物理属性无关的刺激联想显著性的跨模态编码，并且大多数额叶神经元根据刺激的模态发挥不同的作用。
