Institute of Language, Communication, and the Brain, Aix-Marseille Univ, Marseille, France.
Aix-Marseille Univ, INSERM, INS, Inst Neurosci Syst, Marseille, France.
Commun Biol. 2024 Nov 26;7(1):1570. doi: 10.1038/s42003-024-07297-w.
Alpha oscillations in the auditory cortex have been associated with attention and the suppression of irrelevant information. However, their anatomical organization and interaction with other neural processes remain unclear. Do alpha oscillations function as a local mechanism within most neural sources to regulate their internal excitation/inhibition balance, or do they belong to separated inhibitory sources gating information across the auditory network? To address this question, we acquired intracerebral electrophysiological recordings from epilepsy patients during rest and tones listening. Thanks to independent component analysis, we disentangled the different neural sources and labeled them as "oscillatory" if they presented strong alpha oscillations at rest, and/or "evoked" if they displayed a significant evoked response to the stimulation. Our results show that 1) sources are condition-specific and segregated in the auditory cortex, 2) both sources have a high-gamma response followed by an induced alpha suppression, 3) only oscillatory sources present a sustained alpha suppression during all the stimulation period. We hypothesize that there are two different alpha oscillations in the auditory cortex: an induced bottom-up response indicating a selective engagement of the primary cortex to process the stimuli, and a sustained suppression reflecting a general disinhibited state of the network to process sensory information.
听觉皮层中的α振荡与注意力和无关信息的抑制有关。然而，它们的解剖组织和与其他神经过程的相互作用仍不清楚。α振荡是作为大多数神经源内的局部机制起作用，以调节其内部兴奋/抑制平衡，还是属于分离的抑制源，在听觉网络中对信息进行门控？为了解决这个问题，我们在癫痫患者休息和听音调时获取了脑内电生理记录。由于独立成分分析，我们可以分解不同的神经源，如果它们在休息时表现出强烈的α振荡，我们将其标记为“振荡”源，如果它们对刺激显示出显著的诱发反应，则标记为“诱发”源。我们的结果表明：1）源是条件特异性的，并在听觉皮层中分离；2）两种源都有高伽马反应，随后是诱导的α抑制；3）只有振荡源在整个刺激期间都表现出持续的α抑制。我们假设听觉皮层中有两种不同的α振荡：一种是诱导的自上而下的反应，表明初级皮层被选择性地激活以处理刺激；另一种是持续的抑制，反映了网络的一般去抑制状态，以处理感觉信息。
