Integrated Neuroscience Research Team, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan.
Neuroimage. 2012 Feb 15;59(4):3325-38. doi: 10.1016/j.neuroimage.2011.11.067. Epub 2011 Dec 1.
The neural-hemodynamic relationships may vary depending on cortical processing patterns. To investigate how cortical hemodynamics reflects neural activity involving different cortical processing patterns, we delivered electrical stimulation pulses to rat hindpaws, unilaterally or bilaterally, and simultaneously measured electrophysiological (local field potential, LFP < 100 Hz; multiunit activity, MUA>300 Hz) and optical intrinsic signals associated with changes in cerebral blood volume (CBV). Unilateral stimulation evoked neural and optical signals in bilateral primary somatosensory cortices. Ipsilateral optical responses indicating an increased CBV exhibited a peak magnitude of ~30% and mediocaudal shifts relative to contralateral responses. Correlation analyses revealed different scale factors between contralateral and ipsilateral responses in LFP-MUA and LFP-CBV relationships. Bilateral stimulation at varying time intervals evoked hemodynamic responses that were strongly suppressed at 40-ms intervals. This suppression quantitatively reflected suppressed LFP responses to contralateral testing stimulation and not linear summation, with slowly fluctuating LFP responses to ipsilateral conditioning stimulation. Consequently, in the overall responses to bilateral stimulation, CBV-related responses were more linearly correlated with MUA than with LFPs. When extracting high-frequency components (>30 Hz) from LFPs, we found similar scale factors between contralateral and ipsilateral responses in LFP-MUA and LFP-CBV relationships, resulting in significant linear relationships among these components, MUA, and cortical hemodynamics in overall responses to bilateral stimulation. The dependence of LFP-MUA-hemodynamic relationships on cortical processing patterns and the LFP temporal/spectral structure is important for interpreting hemodynamic signals in complex functional paradigms driving diverse cortical processing.
神经-血液动力学关系可能因皮质处理模式而异。为了研究皮质血液动力学如何反映涉及不同皮质处理模式的神经活动，我们向大鼠后足单侧或双侧施加电刺激脉冲，并同时测量与脑血容量（CBV）变化相关的电生理（局部场电位，LFP <100 Hz；多单位活动，MUA>300 Hz）和光学固有信号。单侧刺激在双侧初级体感皮层中诱发神经和光学信号。表示 CBV 增加的同侧光学响应表现出约 30%的峰值幅度，并相对于对侧响应发生中尾侧移位。相关分析显示 LFP-MUA 和 LFP-CBV 关系中同侧和对侧响应之间存在不同的比例因子。在不同时间间隔进行双侧刺激会引起强烈抑制的血液动力学响应，在 40-ms 间隔时抑制。这种抑制定量反映了对侧测试刺激的 LFP 响应抑制，而不是线性总和，同侧条件刺激的 LFP 响应缓慢波动。因此，在双侧刺激的总体响应中，CBV 相关响应与 MUA 的相关性比与 LFP 的相关性更强。从 LFP 中提取高频成分（>30 Hz）时，我们发现 LFP-MUA 和 LFP-CBV 关系中同侧和对侧响应之间存在相似的比例因子，导致这些成分、MUA 和皮质总体响应中的血液动力学之间存在显著的线性关系对双侧刺激。LFP-MUA-血液动力学关系对皮质处理模式和 LFP 时间/频谱结构的依赖性对于解释在驱动不同皮质处理的复杂功能范式中产生的血液动力学信号非常重要。
