Britz Juliane, Michel Christoph M
Functional Brain Mapping Laboratory, Department of Fundamental Neuroscience and Clinic of Neurology, University Medical School and University Hospital of Geneva Geneva, Switzerland.
Front Psychol. 2011 Dec 16;2:370. doi: 10.3389/fpsyg.2011.00370. eCollection 2011.
The temporal dynamics and anatomical correlates underlying human visual cognition are traditionally assessed as a function of stimulus properties and task demands. Any non-stimulus related activity is commonly dismissed as noise and eliminated to extract an evoked signal that is only a small fraction of the magnitude of the measured signal. We review studies that challenge this view by showing that non-stimulus related activity is not mere noise but that it has a well-structured organization which can largely determine the processing of upcoming stimuli. We review recent evidence from human electrophysiology that shows how different aspects of pre-stimulus activity such as pre-stimulus EEG frequency power and phase and pre-stimulus EEG microstates can determine qualitative and quantitative properties of both lower and higher-level visual processing. These studies show that low-level sensory processes depend on the momentary excitability of sensory cortices whereas perceptual processes leading to stimulus awareness depend on momentary pre-stimulus activity in higher-level non-visual brain areas. Also speed and accuracy of stimulus identification have likewise been shown to be modulated by pre-stimulus brain states.
传统上，人类视觉认知背后的时间动态和解剖学关联是根据刺激属性和任务需求来评估的。任何与刺激无关的活动通常都被视为噪声并被消除，以提取一个诱发信号，该信号只是测量信号幅度的一小部分。我们回顾了一些研究，这些研究通过表明与刺激无关的活动并非仅仅是噪声，而是具有一种结构良好的组织，这种组织在很大程度上可以决定对即将到来的刺激的处理，从而对这一观点提出了挑战。我们回顾了来自人类电生理学的最新证据，这些证据表明刺激前活动的不同方面，如刺激前脑电图频率功率和相位以及刺激前脑电图微状态，如何能够决定低级和高级视觉处理的定性和定量属性。这些研究表明，低级感觉过程取决于感觉皮层的瞬间兴奋性，而导致刺激意识的知觉过程则取决于高级非视觉脑区的瞬间刺激前活动。同样，刺激识别的速度和准确性也已被证明会受到刺激前脑状态的调节。
