Extracellular Calcium Controls the Expression of Two Different Forms of Ripple-Like Hippocampal Oscillations
Extracellular Calcium Controls the Expression of Two Different Forms of Ripple-Like Hippocampal Oscillations
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DOI：
10.1523/jneurosci.2826-13.2014
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发表时间：
2014-02-19
影响因子：
5.3
通讯作者：
Menendez de la Prida, Liset
中科院分区：
文献类型：
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作者：
Aivar, Paloma;Valero, Manuel;Menendez de la Prida, Liset
海马区高频振荡(HFO)在生理和病理条件下表现突出。在生理波纹(100-200赫兹)中，少数锥体细胞在节律抑制电位的协调下一起放电。在癫痫患者的海马体中，快速波纹(200赫兹)反映了突起细胞簇的群体尖峰(PSS)，但波纹和快速波纹范围内的HFO大量混合在一起。这个频率范围的含义是什么？是什么决定了不同的HFO的表达？在此，我们用生理范围内(1-3 mM)不同浓度的钙离子记录正常大鼠海马片的局部场电位和单个细胞。令人惊讶的是，我们发现这种单一的操作导致了两种形式的HFO的出现，这两种形式的HFO分别让人想起正常大鼠和癫痫大鼠体内记录的涟漪和快速涟漪。我们仔细研究了这两种形式HFO出现的细胞相关性和机制，方法是将多点、单细胞和成对细胞记录结合在一起，从大鼠报告系制备的切片中进行记录，以便于识别GABA能细胞。我们发现，细胞外钙离子在调节固有兴奋性和双突触抑制中起主要作用，这是影响网络动力学的两个关键因素。此外，在体内环境中局部调节细胞外钙离子浓度对双突触抑制、锥体细胞兴奋性和涟漪动力学也有类似的影响。因此，HFO频段反映了海马网的一系列放电动力学。
Hippocampal high-frequency oscillations (HFOs) are prominent in physiological and pathological conditions. During physiological ripples (100-200 Hz), few pyramidal cells fire together coordinated by rhythmic inhibitory potentials. In the epileptic hippocampus, fast ripples (>200 Hz) reflect population spikes (PSs) from clusters of bursting cells, but HFOs in the ripple and the fast ripple range are vastly intermixed. What is the meaning of this frequency range? What determines the expression of different HFOs? Here, we used different concentrations of Ca2+ in a physiological range (1-3 mM) to record local field potentials and single cells in hippocampal slices from normal rats. Surprisingly, we found that this sole manipulation results in the emergence of two forms of HFOs reminiscent of ripples and fast ripples recorded in vivo from normal and epileptic rats, respectively. We scrutinized the cellular correlates and mechanisms underlying the emergence of these two forms of HFOs by combining multisite, single-cell and paired-cell recordings in slices prepared from a rat reporter line that facilitates identification of GABAergic cells. We found a major effect of extracellular Ca2+ in modulating intrinsic excitability and disynaptic inhibition, two critical factors shaping network dynamics. Moreover, locally modulating the extracellular Ca2+ concentration in an in vivo environment had a similar effect on disynaptic inhibition, pyramidal cell excitability, and ripple dynamics. Therefore, the HFO frequency band reflects a range of firing dynamics of hippocampal networks.