Department of Clinical Neurophysiology, Radboud University Nijmegen Medical Centre and Centre for Cognitive Neuroimaging, Radboud University Nijmegen, Donders Institute for Brain, Cognition, and Behaviour, 6525 EN Nijmegen, The Netherlands.
J Neurosci. 2010 Mar 24;30(12):4481-8. doi: 10.1523/JNEUROSCI.2794-09.2010.
Rhythmic synchronization of neurons in the beta or gamma band occurs almost ubiquitously, and this synchronization has been linked to numerous nervous system functions. Many respective studies make the implicit assumption that neuronal synchronization affects neuronal interactions. Indeed, when neurons synchronize, their output spikes reach postsynaptic neurons together, trigger coincidence detection mechanisms, and therefore have an enhanced impact. There is ample experimental evidence demonstrating this consequence of neuronal synchronization, but beyond this, beta/gamma-band synchronization within a group of neurons might also modulate the impact of synaptic input to that synchronized group. This would constitute a separate mechanism through which synchronization affects neuronal interactions, but direct in vivo evidence for this putative mechanism is lacking. Here, we demonstrate that synchronized beta-band activity of a neuronal group modulates the efficacy of synaptic input to that group in-phase with the beta rhythm. This response modulation was not an addition of rhythmic activity onto the average response but a rhythmic modulation of multiplicative input gain. Our results demonstrate that beta-rhythmic activity of a neuronal target group multiplexes input gain along the rhythm cycle. The actual gain of an input then depends on the precision and the phase of its rhythmic synchronization to this target, providing one mechanistic explanation for why synchronization modulates interactions.
神经元在β或γ频段的节律性同步几乎普遍存在，这种同步与许多神经系统功能有关。许多相关研究都隐含地假设神经元同步会影响神经元之间的相互作用。事实上，当神经元同步时，它们的输出尖峰会一起到达突触后神经元，触发符合检测机制，从而产生更强的影响。有大量实验证据表明了神经元同步的这一结果，但除此之外，一组神经元内的β/γ 频段同步也可能调节对该同步组的突触输入的影响。这将构成一种通过同步影响神经元相互作用的单独机制，但缺乏这种假设机制的直接体内证据。在这里，我们证明了神经元群的同步β波段活动以与β节律同相的方式调节了对该群的突触输入的效能。这种响应调制不是将节律活动添加到平均响应上，而是对乘法输入增益进行节律调制。我们的结果表明，神经元靶群的β节律活动沿着节律周期对输入增益进行了复用。然后，输入的实际增益取决于其与该目标的节律同步的精度和相位，为同步调节相互作用的原因提供了一种机制解释。
