Ceballos Cesar C, Chadly Nourdin, Lowet Eric, Pena Rodrigo F O
Department of Biological Sciences, Florida Atlantic University, Jupiter, Florida, United States of America.
Department of Neuroscience, Erasmus Medical Center, Rotterdam, Netherlands.
PLoS Comput Biol. 2025 May 22;21(5):e1013126. doi: 10.1371/journal.pcbi.1013126. eCollection 2025 May.
Under in vivo conditions, CA1 pyramidal cells from the hippocampus display transitions from single spikes to bursts. It is believed that subthreshold hyperpolarization and depolarization, also known as down and up-states, play a pivotal role in these transitions. Nevertheless, a central impediment to correlating suprathreshold (spiking) and subthreshold activity has been the technical difficulties associated this type of recordings, even with widely used calcium imaging or multielectrode recordings. Recent work using voltage imaging with genetically encoded voltage indicators has been able to correlate spiking patterns with subthreshold activity in a variety of CA1 neurons, and recent computational models have been able to capture these transitions. In this work, we used a computational model of a CA1 pyramidal cell to investigate the role of intrinsic conductances and oscillatory patterns in generating down and up-states and their modulation in the transition from single spiking to bursting. Specifically, we observed the emergence of distinct spiking resonances between these two spiking modes that share the same voltage traces in the presence of theta or gamma oscillatory inputs, a phenomenon we call interleaved single and bursting spiking resonance. We noticed that these resonances do not necessarily overlap in frequency or amplitude, underscoring their relevance for providing flexibility to neural processing. We studied the conductance values of three current types that are thought to be critical for the bursting behavior: persistent sodium current (INaP) and its conductance GNaP, delayed rectifier potassium (IKDR) and its conductance GKDR, and hyperpolarization-activated current (Ih) and its conductance Gh. We conclude that the intricate interplay of ionic currents significantly influences the neuronal firing patterns, transitioning from single to burst firing during sustained depolarization. Specifically, the intermediate levels of GNaP and GKDR facilitate spiking resonance at gamma-frequency inputs. The resonance characteristics vary between single and burst firing modes, each displaying distinct amplitudes and resonant frequencies. Furthermore, low GNaP and high GKDR values lock bursting to theta frequencies, while high GNaP and low GKDR values lock single spiking to gamma frequencies. Lastly, the duration of quiet intervals plays a crucial role in determining the likelihood of transitioning to either bursting or single spiking modes. We confirmed that the same features were present in previously recorded in vivo voltage-imaging data. Understanding these dynamics provides valuable insights into the fundamental mechanisms underlying neuronal excitability under in vivo conditions.
在体内条件下,海马体的CA1锥体细胞会表现出从单个动作电位到爆发式放电的转变。据信,阈下超极化和去极化,也就是所谓的下行和上行状态,在这些转变中起着关键作用。然而,将阈上(动作电位发放)和阈下活动相关联的一个主要障碍一直是与这类记录相关的技术难题,即便使用广泛应用的钙成像或多电极记录也是如此。最近利用基因编码电压指示剂进行电压成像的研究工作,已经能够将各种CA1神经元中的动作电位发放模式与阈下活动相关联,并且最近的计算模型也已经能够捕捉这些转变。在这项工作中,我们使用一个CA1锥体细胞的计算模型,来研究内在电导和振荡模式在产生下行和上行状态以及它们在从单个动作电位发放到爆发式放电转变过程中的调制作用。具体而言,我们观察到在存在theta或gamma振荡输入时,这两种具有相同电压轨迹的动作电位发放模式之间出现了明显的动作电位发放共振,我们将这种现象称为交错式单个和爆发式动作电位发放共振。我们注意到这些共振在频率或幅度上不一定重叠,这突出了它们对于为神经处理提供灵活性的相关性。我们研究了三种被认为对爆发式行为至关重要的电流类型的电导值:持续性钠电流(INaP)及其电导GNaP、延迟整流钾电流(IKDR)及其电导GKDR、超极化激活电流(Ih)及其电导Gh。我们得出结论,离子电流的复杂相互作用显著影响神经元的放电模式,在持续去极化过程中从单个动作电位发放转变为爆发式放电。具体来说,GNaP和GKDR的中间水平促进了gamma频率输入时的动作电位发放共振。共振特征在单个动作电位发放和爆发式放电模式之间有所不同,每种模式都显示出不同的幅度和共振频率。此外,低GNaP和高GKDR值使爆发式放电锁定在theta频率,而高GNaP和低GKDR值使单个动作电位发放锁定在gamma频率。最后,静息间隔的持续时间在决定转变为爆发式放电或单个动作电位发放模式的可能性方面起着关键作用。我们证实,相同的特征也存在于先前记录的体内电压成像数据中。理解这些动态过程为深入了解体内条件下神经元兴奋性的基本机制提供了有价值的见解。