UCL Institute of Neurology, University College London, London, United Kingdom.
Champalimaud Neuroscience Program, Champalimaud Center for the Unknown, Lisbon, Portugal.
Elife. 2018 Oct 23;7:e38346. doi: 10.7554/eLife.38346.
Gamma-band oscillations are implicated in modulation of attention, integration of sensory information and flexible communication among anatomically connected brain areas. How networks become entrained is incompletely understood. Specifically, it is unclear how the spectral and temporal characteristics of network oscillations can be altered on rapid timescales needed for efficient communication. We use closed-loop optogenetic modulation of principal cell excitability in mouse hippocampal slices to interrogate the dynamical properties of hippocampal oscillations. Gamma frequency and amplitude can be modulated bi-directionally, and dissociated, by phase-advancing or delaying optogenetic feedback to pyramidal cells. Closed-loop modulation alters the synchrony rather than average frequency of action potentials, in principle avoiding disruption of population rate-coding of information. Modulation of phasic excitatory currents in principal neurons is sufficient to manipulate oscillations, suggesting that feed-forward excitation of pyramidal cells has an important role in determining oscillatory dynamics and the ability of networks to couple with one another.
伽马波段振荡被认为参与了注意力的调节、感觉信息的整合以及解剖连接的脑区之间的灵活通讯。但是，网络如何被锁定在同步状态还不完全清楚。具体来说，目前尚不清楚如何在快速时间尺度上改变网络振荡的频谱和时频特性，以实现有效的通讯。我们使用闭环光遗传调制小鼠海马切片中的主细胞兴奋性，以研究海马振荡的动力学特性。通过相位提前或延迟光遗传反馈到锥体细胞，可以双向和分离地调制伽马频率和幅度。闭环调制改变了动作电位的同步性而不是平均频率，原则上避免了对信息群体率编码的破坏。主神经元的相位兴奋性电流的调制足以操纵振荡，这表明锥体细胞的前馈兴奋在确定振荡动力学和网络彼此耦合的能力方面起着重要作用。
