Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research (CNCR), Neuroscience Campus Amsterdam, VU University, The Netherlands.
Brain Res. 2010 Mar 19;1321:31-9. doi: 10.1016/j.brainres.2010.01.047. Epub 2010 Jan 28.
Primary sensory cortical areas continuously receive thalamic inputs that arrive at different frequencies depending on the amount of sensory activity. The cortical response to repeated sensory stimuli rapidly adapts and different frequencies recruit cortical neuronal networks to different extents. GABAergic inhibition limits the spread of excitation within cortical neuronal networks. However, it is unknown how frequency adaptation of cortical network activity at different frequencies is shaped by GABAergic inhibition. Here, we find that in acute slices of visual cortex area V1 GABAergic inhibition affects frequency adaptation depending on the frequency of activity. Using voltage-sensitive dye imaging, we found that while increasing inhibitory postsynaptic currents (IPSCs) with flunitrazepam dampened the spread of cortical excitation, short-term adaptations to different stimulation frequencies were differentially affected. At high frequencies (40 Hz), facilitation of cortical excitation was no longer transient, but facilitation was sustained. At low frequencies (10 Hz) flunitrazepam decreased a depression of the excitation. In contrast, in mice lacking the GABA(A) receptor alpha1 subunit facilitation was reduced and depression enhanced. These findings suggest that GABAergic inhibition affects cortical excitation at different frequencies differentially, favoring facilitation at higher frequencies of excitation.
初级感觉皮层区域持续接收来自丘脑的输入，这些输入的频率取决于感觉活动的数量。皮质对重复感觉刺激的反应迅速适应，不同的频率以不同的程度招募皮质神经元网络。GABA 能抑制限制了皮质神经元网络内兴奋的扩散。然而，目前尚不清楚不同频率的皮质网络活动的频率适应如何受到 GABA 能抑制的影响。在这里，我们发现，在视觉皮层 V1 的急性切片中，GABA 能抑制取决于活动的频率来影响频率适应。使用电压敏感染料成像，我们发现，虽然用氟硝西泮增加抑制性突触后电流（IPSCs）会减弱皮质兴奋的扩散，但对不同刺激频率的短期适应会受到不同的影响。在高频（40 Hz）下，皮质兴奋的易化不再是瞬时的，而是持续的。在低频（10 Hz）下，氟硝西泮减少了兴奋的抑制。相比之下，在缺乏 GABA(A)受体α1 亚基的小鼠中，易化作用减弱，而抑制作用增强。这些发现表明，GABA 能抑制以不同的方式影响不同频率的皮质兴奋，有利于高频兴奋的易化。
