Instituto de Investigacion en Biomedicina de Buenos Aires (IBioBA) - CONICET/Partner Institute of the Max Planck Society, Polo Cientifico Tecnologico, Buenos Aires, Argentina.
Departamento de Fisica, FCEyN UBA, Ciudad Universitaria, Buenos Aires, Argentina.
Elife. 2023 Aug 16;12:e80250. doi: 10.7554/eLife.80250.
Heterogeneity plays an important role in diversifying neural responses to support brain function. Adult neurogenesis provides the dentate gyrus with a heterogeneous population of granule cells (GCs) that were born and developed their properties at different times. Immature GCs have distinct intrinsic and synaptic properties than mature GCs and are needed for correct encoding and discrimination in spatial tasks. How immature GCs enhance the encoding of information to support these functions is not well understood. Here, we record the responses to fluctuating current injections of GCs of different ages in mouse hippocampal slices to study how they encode stimuli. Immature GCs produce unreliable responses compared to mature GCs, exhibiting imprecise spike timings across repeated stimulation. We use a statistical model to describe the stimulus-response transformation performed by GCs of different ages. We fit this model to the data and obtain parameters that capture GCs' encoding properties. Parameter values from this fit reflect the maturational differences of the population and indicate that immature GCs perform a differential encoding of stimuli. To study how this age heterogeneity influences encoding by a population, we perform stimulus decoding using populations that contain GCs of different ages. We find that, despite their individual unreliability, immature GCs enhance the fidelity of the signal encoded by the population and improve the discrimination of similar time-dependent stimuli. Thus, the observed heterogeneity confers the population with enhanced encoding capabilities.
异质性在多样化神经反应以支持大脑功能方面起着重要作用。成年神经发生为齿状回提供了异质的颗粒细胞 (GC) 群体，这些细胞在不同时间产生并发展其特性。未成熟的 GC 具有与成熟 GC 不同的内在和突触特性，是正确编码和区分空间任务所必需的。未成熟 GC 如何增强信息编码以支持这些功能还不是很清楚。在这里，我们记录了不同年龄的 GC 在小鼠海马切片中对波动电流注入的反应，以研究它们如何编码刺激。与成熟 GC 相比，未成熟 GC 的反应不可靠，在重复刺激时表现出不准确的尖峰定时。我们使用统计模型来描述不同年龄 GC 的刺激-反应转换。我们将该模型拟合到数据中，并获得捕获 GC 编码特性的参数。该拟合的参数值反映了群体的成熟差异，并表明未成熟 GC 对刺激进行了差异编码。为了研究这种年龄异质性如何通过群体进行编码，我们使用包含不同年龄 GC 的群体进行刺激解码。我们发现，尽管个体不可靠，但未成熟 GC 增强了群体编码信号的保真度，并提高了对相似时变刺激的区分能力。因此，观察到的异质性赋予了群体增强的编码能力。
