Vanzella Walter, Grion Natalia, Bertolini Daniele, Perissinotto Andrea, Gigante Marco, Zoccolan Davide
Visual Neuroscience Laboratory, International School for Advanced Studies (SISSA), Trieste, Italy.
Glance Vision Technologies, Trieste, Italy.
J Neurophysiol. 2019 Dec 1;122(6):2220-2242. doi: 10.1152/jn.00301.2019. Epub 2019 Sep 25.
Tracking head position and orientation in small mammals is crucial for many applications in the field of behavioral neurophysiology, from the study of spatial navigation to the investigation of active sensing and perceptual representations. Many approaches to head tracking exist, but most of them only estimate the 2D coordinates of the head over the plane where the animal navigates. Full reconstruction of the pose of the head in 3D is much more more challenging and has been achieved only in handful of studies, which employed headsets made of multiple LEDs or inertial units. However, these assemblies are rather bulky and need to be powered to operate, which prevents their application in wireless experiments and in the small enclosures often used in perceptual studies. Here we propose an alternative approach, based on passively imaging a lightweight, compact, 3D structure, painted with a pattern of black dots over a white background. By applying a cascade of feature extraction algorithms that progressively refine the detection of the dots and reconstruct their geometry, we developed a tracking method that is highly precise and accurate, as assessed through a battery of validation measurements. We show that this method can be used to study how a rat samples sensory stimuli during a perceptual discrimination task and how a hippocampal place cell represents head position over extremely small spatial scales. Given its minimal encumbrance and wireless nature, our method could be ideal for high-throughput applications, where tens of animals need to be simultaneously and continuously tracked. Head tracking is crucial in many behavioral neurophysiology studies. Yet reconstruction of the head's pose in 3D is challenging and typically requires implanting bulky, electrically powered headsets that prevent wireless experiments and are hard to employ in operant boxes. Here we propose an alternative approach, based on passively imaging a compact, 3D dot pattern that, once implanted over the head of a rodent, allows estimating the pose of its head with high precision and accuracy.
在行为神经生理学领域，跟踪小型哺乳动物的头部位置和方向对于许多应用至关重要，从空间导航研究到主动感知和知觉表征的研究皆是如此。存在许多头部跟踪方法，但大多数方法仅估计动物在其导航平面上的头部二维坐标。在三维空间中完全重建头部姿态更具挑战性，并且仅在少数研究中得以实现，这些研究采用了由多个发光二极管或惯性单元制成的头戴设备。然而，这些组件相当笨重且需要供电才能运行，这阻碍了它们在无线实验以及知觉研究中常用的小笼子中的应用。在此，我们提出一种替代方法，该方法基于对一个轻巧、紧凑的三维结构进行被动成像，该结构在白色背景上绘制有黑点图案。通过应用一系列特征提取算法，逐步细化对点的检测并重建其几何形状，我们开发了一种跟踪方法，通过一系列验证测量评估，该方法具有高度的精确性和准确性。我们表明，这种方法可用于研究大鼠在知觉辨别任务期间如何采样感觉刺激，以及海马体位置细胞如何在极小的空间尺度上表征头部位置。鉴于其最小的负担和无线特性，我们的方法对于需要同时连续跟踪数十只动物的高通量应用可能是理想的。头部跟踪在许多行为神经生理学研究中至关重要。然而，在三维空间中重建头部姿态具有挑战性，通常需要植入笨重的、供电的头戴设备，这会妨碍无线实验，并且难以在操作箱中使用。在此，我们提出一种替代方法，该方法基于对一个紧凑的三维点状图案进行被动成像，一旦将其植入啮齿动物头部上方，就可以高精度和准确地估计其头部姿态。
