Spontaneous brain activity has been widely used to map brain connectivity. The interactions between task-evoked brain responses and the spontaneous cortical oscillations, especially within the low frequency range of ∼0.1 Hz, are not fully understood. Trial-to-trial variabilities in brain's response to sensory stimuli and the ability for brain to detect under noisy conditions suggest an appreciable impact of the brain state. Using a multimodality imaging platform, we simultaneously imaged neuronal Ca2+ and cerebral hemodynamics at baseline and in response to single-pulse forepaw stimuli in rat's somatosensory cortex. The high sensitivity of this system enables detection of responses to very weak and strong stimuli and real time determination of low frequency oscillations without averaging. Results show that the ongoing neuronal oscillations inversely modulate Ca2+ transients evoked by sensory stimuli. High intensity stimuli reset the spontaneous neuronal oscillations to an unpreferable excitability following the stimulus. Cerebral hemodynamic responses also inversely interact with the spontaneous hemodynamic oscillations, correlating with the neuronal Ca2+ transient changes. The results reveal competing interactions between spontaneous oscillations and stimulation-evoked brain activities in somatosensory cortex and the resultant hemodynamics.

中文翻译：

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刺激诱发的皮质活动与神经元钙测量的自发低频振荡之间的相互作用

自发的大脑活动已被广泛用于绘制大脑连接图。任务诱发的大脑反应与自发皮层振荡之间的相互作用，尤其是在 ~0.1 Hz 的低频范围内，尚未完全了解。大脑对感官刺激的反应和大脑在嘈杂条件下检测的能力的试验之间的差异表明大脑状态的显着影响。使用多模态成像平台，我们同时对基线时的神经元 Ca2+ 和脑血流动力学进行成像，并响应大鼠躯体感觉皮层中的单脉冲前爪刺激。该系统的高灵敏度能够检测对非常微弱和强烈刺激的反应，并实时确定低频振荡而无需求平均值。结果表明，正在进行的神经元振荡反向调节由感觉刺激引起的 Ca2+ 瞬变。高强度刺激将自发的神经元振荡重置为刺激后不可取的兴奋性。脑血流动力学反应也与自发血流动力学振荡反向相互作用，与神经元 Ca2+ 瞬态变化相关。结果揭示了自发振荡与体感皮层中刺激诱发的大脑活动之间的竞争相互作用以及由此产生的血流动力学。与神经元 Ca2+ 瞬态变化相关。结果揭示了自发振荡与体感皮层中刺激诱发的大脑活动之间的竞争相互作用以及由此产生的血流动力学。与神经元 Ca2+ 瞬态变化相关。结果揭示了自发振荡与体感皮层中刺激诱发的大脑活动之间的竞争相互作用以及由此产生的血流动力学。