Schwartz Rina, Rozier Camille, Seidel Malkinson Tal, Lehongre Katia, Adam Claude, Lambrecq Virginie, Navarro Vincent, Naccache Lionel, Axelrod Vadim
The Gonda Multidisciplinary Brain Research Center, Bar Ilan University, Ramat Gan 52900, Israel.
Institut National de la Santé et de la Recherche Médicale Unité 1127, Centre National de la Recherche Scientifique Unité Mixte de Recherche (UMR) 7225, Université Pierre-et-Marie-Curie Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle Épinière ICM, Paris 75013, France.
Neurosci Conscious. 2021 Oct 16;2021(2):niab033. doi: 10.1093/nc/niab033. eCollection 2021.
The stimulus-evoked neural response is a widely explored phenomenon. Conscious awareness is associated in many cases with the corresponding selective stimulus-evoked response. For example, conscious awareness of a face stimulus is associated with or accompanied by stimulus-evoked activity in the fusiform face area (FFA). In addition to the stimulus-evoked response, spontaneous (i.e. task-unrelated) activity in the brain is also abundant. Notably, spontaneous activity is considered unconscious. For example, spontaneous activity in the FFA is not associated with conscious awareness of a face. The question is: what is the difference at the neural level between stimulus-evoked activity in a case that this activity is associated with conscious awareness of some content (e.g. activity in the FFA in response to fully visible face stimuli) and spontaneous activity in that same region of the brain? To answer this question, in the present study, we had a rare opportunity to record two face-selective multi-units in the vicinity of the FFA in a human patient. We compared multi-unit face-selective task-evoked activity with spontaneous prestimulus and a resting-state activity. We found that when activity was examined over relatively long temporal windows (e.g. 100-200 ms), face-selective stimulus-evoked firing in the recorded multi-units was much higher than the spontaneous activity. In contrast, when activity was examined over relatively short windows, we found many cases of high firing rates within the spontaneous activity that were comparable to stimulus-evoked activity. Our results thus indicate that the sustained activity is what might differentiate between stimulus-evoked activity that is associated with conscious awareness and spontaneous activity.
刺激诱发的神经反应是一个被广泛研究的现象。在许多情况下，意识觉知与相应的选择性刺激诱发反应相关联。例如，对面部刺激的意识觉知与梭状面孔区（FFA）中刺激诱发的活动相关联或伴随出现。除了刺激诱发反应外，大脑中的自发（即与任务无关）活动也很丰富。值得注意的是，自发活动被认为是无意识的。例如，FFA中的自发活动与对面部的意识觉知无关。问题在于：在神经层面上，与对某些内容的意识觉知相关联的刺激诱发活动（例如FFA中对完全可见的面部刺激作出反应的活动）与大脑同一区域的自发活动之间有什么区别？为了回答这个问题，在本研究中，我们获得了一个难得的机会，在一名人类患者的FFA附近记录了两个对面部有选择性反应的多单元活动。我们将多单元对面部有选择性的任务诱发活动与刺激前的自发活动以及静息状态活动进行了比较。我们发现，当在相对较长的时间窗口（例如100 - 200毫秒）内检查活动时，记录的多单元中对面部有选择性的刺激诱发放电远高于自发活动。相比之下，当在相对较短的窗口内检查活动时，我们发现在自发活动中有许多高放电率的情况，这些情况与刺激诱发活动相当。因此，我们的结果表明，持续活动可能是与意识觉知相关联的刺激诱发活动和自发活动之间的区别所在。
