Recurrent synaptic input and the timing of gamma-frequency-modulated firing of pyramidal cells during neocortical "UP" states
Recurrent synaptic input and the timing of gamma-frequency-modulated firing of pyramidal cells during neocortical "UP" states
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DOI：
10.1523/jneurosci.3948-07.2008
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发表时间：
2008-02-20
影响因子：
5.3
通讯作者：
Robinson, Hugh P. C.
中科院分区：
文献类型：
--
作者：
Morita, Kenji;Kalra, Rita;Robinson, Hugh P. C.
伽马(Gamma)振荡是感觉处理和认知过程中皮质活动的一个标志，发生在持续的自我维持的活动或“向上”状态，这种状态被认为是由反复向锥体细胞的突触输入维持的。在新皮层“上”状态，兴奋性规则峰电位(RS)(锥体)细胞和抑制性快速峰电位(FS)细胞(篮子)放电时，相对于局部场电位的伽马振荡，它们具有不同的相位分布。证据表明，伽马调制的RS->FS输入起到同步中间神经元的作用，从而产生伽马调制的FS->RS驱动。然而，RS->；RS的反复输入如何影响自我维持的活动和伽马调节的阶段性放电，目前尚不清楚。在这里，我们通过在大脑皮层脑片上使用电导注入(动态钳制)技术重建到RS细胞的伽马调制突触输入来研究这一点。我们发现，为了显示逼真的伽马调制放电，RS细胞需要来自FS细胞的强烈伽马调制、低潜伏期抑制输入，但很少或没有来自反复RS->RS连接的伽马调制。我们认为，与抑制相比，这种对周期性兴奋的解调反映了几种可能的影响，包括分布的传播延迟和兴奋在更广泛区域的整合，并通过周期性兴奋的时间最大化了表征信息的能力。
Gamma (gamma) oscillation, a hallmark of cortical activity during sensory processing and cognition, occurs during persistent, self-sustained activity or "UP" states, which are thought to be maintained by recurrent synaptic inputs to pyramidal cells. During neocortical "UP" states, excitatory regular spiking (RS) (pyramidal) cells and inhibitory fast spiking (FS) (basket) cells fire with distinct phase distributions relative to the gamma oscillation in the local field potential. Evidence suggests that gamma-modulated RS -> FS input serves to synchronize the interneurons and hence to generate gamma-modulated FS -> RS drive. How RS -> RS recurrent input shapes both self-sustained activity and gamma-modulated phasic firing, although, is unclear. Here, we investigate this by reconstructing gamma-modulated synaptic input to RS cells using the conductance injection (dynamic clamp) technique in cortical slices. We find that, to show lifelike gamma-modulated firing, RS cells require strongly gamma-modulated, low-latency inhibitory inputs from FS cells but little or no gamma-modulation from recurrent RS -> RS connections. We suggest that this demodulation of recurrent excitation, compared with inhibition, reflects several possible effects, including distributed propagation delays and integration of excitation over wider areas of cortex, and maximizes the capacity for representing information by the timing of recurrent excitation.