Departamento de Anatomía, Histología y Neurociencia, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid 28029, Spain.
Blue Brain Project; École Polytechnique Fédéral de Lausanne, 1015 Lausanne, Switzerland.
eNeuro. 2019 Apr 2;6(2). doi: 10.1523/ENEURO.0471-18.2019. eCollection 2019 Mar-Apr.
Rodents use rhythmic whisker movements at frequencies between 4 and 12 Hz to sense the environment that will be disturbed when the animal touches an object. The aim of this work is to study the response adaptation to rhythmic whisker stimulation trains at 4 Hz in the barrel cortex and the sensitivity of cortical neurons to changes in the timing of the stimulation pattern. Longitudinal arrays of four iridium oxide electrodes were used to obtain single-unit recordings in supragranular, granular, and infragranular neurons in urethane anesthetized mice. The stimulation protocol consisted in a stimulation train of three air puffs (20 ms duration each) in which the time interval between the first and the third stimuli was fixed (500 ms) and the time interval between the first and the second stimuli changed (regular: 250 ms; "accelerando": 375 ms; or "decelerando" stimulation train: 125 ms interval). Cortical neurons adapted strongly their response to regular stimulation trains. Response adaptation was reduced when accelerando or decelerando stimulation trains were applied. This facilitation of the shifted stimulus was mediated by activation of NMDA receptors because the effect was blocked by AP5. The facilitation was not observed in thalamic nuclei. Facilitation increased during periods of EEG activation induced by systemic application of IGF-I, probably by activation of NMDA receptors, as well. We suggest that response adaptation is the outcome of an intrinsic cortical information processing aimed at contributing to improve the detection of "unexpected" stimuli that disturbed the rhythmic behavior of exploration.
啮齿动物使用频率在 4 到 12 Hz 之间的有节奏的胡须运动来感知环境，当动物触碰到物体时，环境会被扰乱。这项工作的目的是研究在 4 Hz 的节律性胡须刺激训练下，在桶状皮层中的反应适应，以及皮层神经元对刺激模式时间变化的敏感性。纵向排列的四个氧化铱电极用于在麻醉的小鼠的颗粒上层、颗粒层和颗粒下层神经元中获得单细胞记录。刺激方案由三个空气脉冲的刺激序列组成（每个持续 20 毫秒），其中第一个和第三个刺激之间的时间间隔固定（500 毫秒），而第一个和第二个刺激之间的时间间隔变化（规则：250 毫秒；“加速”：375 毫秒；或“减速”刺激序列：125 毫秒间隔）。皮质神经元对规则刺激序列的反应强烈适应。当应用加速或减速刺激序列时，反应适应会降低。这种对移位刺激的促进作用是由 NMDA 受体的激活介导的，因为 AP5 阻断了这种作用。这种促进作用在丘脑核中没有观察到。在 IGF-I 全身应用诱导的 EEG 激活期间，促进作用增加，这可能是通过 NMDA 受体的激活引起的。我们认为，反应适应是一种内在的皮质信息处理的结果，旨在有助于提高对扰乱探索节律行为的“意外”刺激的检测。
