As sensory information moves through the brain, higher-order areas exhibit more complex tuning than lower areas. Though models predict that complexity arises via convergent inputs from neurons with diverse response properties, in most vertebrate systems, convergence has only been inferred rather than tested directly. Here, we measure sensory computations in zebrafish vestibular neurons across multiple axes in vivo. We establish that whole-cell physiological recordings reveal tuning of individual vestibular afferent inputs and their postsynaptic targets. Strong, sparse synaptic inputs can be distinguished by their amplitudes, permitting analysis of afferent convergence in vivo. An independent approach, serial-section electron microscopy, supports the inferred connectivity. We find that afferents with similar or differing preferred directions converge on central vestibular neurons, conferring more simple or complex tuning, respectively. Together, these results provide a direct, quantifiable demonstration of feedforward input convergence in vivo.

当感觉信息在大脑中移动时，高阶区域比低阶区域表现出更复杂的调谐。尽管模型预测复杂性是通过来自具有不同响应特性的神经元的收敛输入产生的，但在大多数脊椎动物系统中，收敛性只是被推断而不是直接测试。在这里，我们测量了体内多轴斑马鱼前庭神经元的感觉计算。我们确定全细胞生理记录揭示了个体前庭传入输入及其突触后目标的调整。强、稀疏的突触输入可以通过它们的幅度来区分，从而允许分析体内传入收敛. 一种独立的方法，连续切片电子显微镜，支持推断的连通性。我们发现具有相似或不同首选方向的传入神经会聚在中央前庭神经元上，分别赋予更简单或复杂的调谐。总之，这些结果提供了体内前馈输入收敛的直接、可量化的证明。