Research on the physiological mechanisms of 'recognition'

已有许多研究对物体识别的神经机制进行了研究。在视觉通道中，信息流被追踪到从视网膜到颞叶联合皮质，已有研究表明，神经元的感受野越大，其触发特征越复杂，信息处理的阶段越晚。例如，据报道，猴子的上颞沟中有神经元对面孔做出反应。然而，无论这些位于上颞沟的神经元有什么复杂的触发特征，它们都只对“它是什么”进行编码。另一方面，生物体也提取刺激的另一个方面：“刺激的意义”。这项研究是为了找出物体识别的神经元基础与刺激的意义，特别是刺激的联想意义。记录了猴子的额叶皮质的单个单位活动，并对其进行了刺激-奖赏联想学习。结果表明，约28%的任务相关单位与刺激的这种联想意义有关，而与其物理性质无关。通过使用具有相同联想意义的视觉和听觉刺激，进一步考察了意义相关的性质。结果表明，在线索相关的差异单位中，不依赖于刺激的情态对刺激的联想意义进行编码的跨通道意义相关单位所占的比例相对较小。根据刺激方式的不同，大多数额叶单位的行为方式不同。结果表明，额叶皮质中多种感觉输入的汇聚并不能很好地支持刺激意义的交叉通道编码。

Many studies have been done to investigate neural mechanisms of object recognition. In the visual modality, the flow of information is traced from the retina to the temporal association cortex, and it has been shown that the receptive fields of the neurons become larger and their trigger features become more comples, the later the stage of informaion processing. For example, neurons are reported in the superior temporal sulcus of the monkey which respond to faces. However, whatever complex trigger features these neurons in the superior temporal sulcus have, they code only 'what it is'. On the other hand, organisms extract the other aspect of the stimulus as well; 'meaning of the stimulus'. This study was conducted to find out neuronal substrates of object recognition in relation to the meaning of the stimulus, especially the 'associative significance of the stimulus'.Single unit activity was recorded from the frontal cortex of the monkey which was trained on a stimulus-reward association learning. The results indicated that about 28% of task-related units were related to this associative significance of the stimulus independent of its physical properties.Meaning-related properties were further examined by employing both visual and auditory stimuli which had the same associative significance. It was shown that the proportion of crossmodal meaning-related units which code the associative significance of the stimulus independent of its modality was relatively small among the cue-related differential units. Majority of frontal units behaved in different ways depending on the modality of the stimulus. The results indicate that the convergence of several modalities of sensory inputs in the frontal cortex does not well substantiate the crossmodal coding of the meaning of the stimulus.