Desmedt J E, Tomberg C
Brain Research Unit, University of Brussels, Belgium.
Electroencephalogr Clin Neurophysiol Suppl. 1995;44:227-34.
Consciousness offers a major challenge to the neurosciences. Even though consciousness is by definition subjective and private to the organism concerned, we consider it to be an intrinsic feature of biological processes in the brain. As such, it should be viewed in the Darwinian perspective of natural selection which implies that the conscious brain function does have survival value and cannot be a mere epiphenomenon. We attempted a neurophysiological approach by assessing perceptual processing of simple somatic sensory inputs in humans. We found that short-latency cortical potentials evoked by a target finger stimulus attended by the subject are strongly enhanced, thus manifesting a remarkable potentiation of the cognitive representations in primary parietal cortex. About 80 msec later, the dorsolateral prefrontal cortex discloses enhanced electrogeneses which we believe to reflect activation of somatic representations in 'working memory'. A functional 'binding' between these critical areas has been revealed by the transient and selective synchrony of 40 Hz oscillations recorded in the cortical areas of the parietal and prefrontal cortices. We consider these re-entrant interactions at 40 Hz to be an essential part of the conscious brain mechanisms that achieve the identification of an object (in this example, a finger) and the decision to release a motor behavioral response.
意识给神经科学带来了重大挑战。尽管从定义上讲，意识是相关生物体主观且私密的，但我们认为它是大脑生物过程的一个内在特征。因此，应该从自然选择的达尔文主义视角来看待它，这意味着有意识的大脑功能确实具有生存价值，而不可能仅仅是一种附带现象。我们尝试通过评估人类对简单躯体感觉输入的感知处理来采用一种神经生理学方法。我们发现，被受试者关注的目标手指刺激所诱发的短潜伏期皮层电位会大幅增强，从而在初级顶叶皮层中表现出认知表征的显著增强。大约80毫秒后，背外侧前额叶皮层显示出增强的电活动，我们认为这反映了“工作记忆”中躯体表征的激活。顶叶和前额叶皮层区域记录到的40赫兹振荡的短暂且选择性同步揭示了这些关键区域之间的功能性“绑定”。我们认为这些40赫兹的折返式相互作用是有意识大脑机制的重要组成部分，这些机制实现了对物体（在此例中为手指）的识别以及做出释放运动行为反应的决定。
