Neuroscience Graduate Program.
Department of Biology.
J Neurosci. 2023 Sep 20;43(38):6495-6507. doi: 10.1523/JNEUROSCI.0925-23.2023. Epub 2023 Aug 21.
The brain combines two-dimensional images received from the two eyes to form a percept of three-dimensional surroundings. This process of binocular integration in the primary visual cortex (V1) serves as a useful model for studying how neural circuits generate emergent properties from multiple input signals. Here, we perform a thorough characterization of binocular integration using electrophysiological recordings in the V1 of awake adult male and female mice by systematically varying the orientation and phase disparity of monocular and binocular stimuli. We reveal widespread binocular integration in mouse V1 and demonstrate that the three commonly studied binocular properties-ocular dominance, interocular matching, and disparity selectivity-are independent of each other. For individual neurons, the responses to monocular stimulation can predict the average amplitude of binocular response but not its selectivity. Finally, the extensive and independent binocular integration of monocular inputs is seen across cortical layers in both regular-spiking and fast-spiking neurons, regardless of stimulus design. Our data indicate that the current model of simple feedforward convergence is inadequate to account for binocular integration in mouse V1, thus suggesting an indispensable role played by intracortical circuits in binocular computation. Binocular integration is an important step of visual processing that takes place in the visual cortex. Studying the process by which V1 neurons become selective for certain binocular disparities is informative about how neural circuits integrate multiple information streams at a more general level. Here, we systematically characterize binocular integration in mice. Our data demonstrate more widespread and complex binocular integration in mouse V1 than previously reported. Binocular responses cannot be explained by a simple convergence of monocular responses, contrary to the prevailing model of binocular integration. These findings thus indicate that intracortical circuits must be involved in the exquisite computation of binocular disparity, which would endow brain circuits with the plasticity needed for binocular development and processing.
大脑将来自两只眼睛的二维图像组合起来，形成对三维环境的感知。初级视觉皮层 (V1) 中的双眼整合过程是研究神经回路如何从多个输入信号中产生涌现特性的有用模型。在这里，我们通过在清醒成年雄性和雌性小鼠的 V1 中进行电生理记录，系统地改变单眼和双眼刺激的方向和相位失配，对双眼整合进行了彻底的表征。我们揭示了小鼠 V1 中广泛的双眼整合，并证明了三种常见的双眼特性——眼优势、眼间匹配和视差选择性——彼此独立。对于单个神经元，对单眼刺激的反应可以预测双眼反应的平均幅度，但不能预测其选择性。最后，无论刺激设计如何，在普通棘突和快速棘突神经元中，单眼输入的广泛且独立的双眼整合都可以在皮层各层中看到。我们的数据表明，目前简单前馈会聚的模型不足以解释小鼠 V1 中的双眼整合，因此表明在双眼计算中，皮层内电路起着不可或缺的作用。双眼整合是视觉处理的一个重要步骤，发生在视觉皮层中。研究 V1 神经元对特定双眼视差变得具有选择性的过程，可以了解神经回路在更一般的水平上如何整合多个信息流。在这里，我们系统地描述了小鼠的双眼整合。我们的数据表明，与之前报道的相比，小鼠 V1 中的双眼整合更为广泛和复杂。与双眼整合的主流模型相反，双眼反应不能用简单的单眼反应汇聚来解释。这些发现表明，皮层内电路必须参与双眼视差的精细计算，这将赋予大脑电路进行双眼发育和处理所需的可塑性。
