RI: SMALL: Collaborative Research: Investigations of the Role of Dorsal versus Ventral Place and Grid Cells during Multi-Scale Spatial Navigation in Rats and Robots

空间导航是一个复杂的认知过程，它依赖于强大的自适应机制来将当前和未来的空间位置与环境中的特定位置联系起来。该项目的目标是通过整合从大鼠实验研究、计算模型和机器人实验中获得的信息来更好地理解空间导航，这些信息将测试关于这些机制如何工作的新假设。海马和内侧内嗅皮层（MEC）是哺乳动物空间导航的主要脑区。虽然位置细胞在海马体中的作用已被广泛研究，但关于MEC网格细胞的功能作用及其与海马体位置细胞的相互作用仍有许多悬而未决的问题。对这一提议感兴趣的是最近的发现，网格细胞沿着MEC的背-腹轴以有序的方式组织，背网格比腹网格间隔更紧密。研究人员假设，这种多尺度组织赋予导航系统一种编码机制，该机制将固有地实现对外部扰动（如障碍物或视觉线索的意外变化）的鲁棒性。为了评估这一假设，研究人员将开发计算和机器人模型，同时系统地在大鼠身上进行实验，其中MEC的背侧或腹侧部分或海马将被灭活。他们将引入新的迷宫类型，其中轨迹的空间频率将被控制。这项工作将有助于更好的机器人空间导航：(1)提供一个机器人测试平台来评估关于内嗅皮层作用的假设；(2)为不确定和动态环境下的鲁棒空间导航提供生物学上合理的模型。这些模型将为机器人同步定位和映射范例中常用的经典概率方法提供替代方案。这项工作还将有助于大鼠空间导航的研究：(1)显示机器人在提供纯计算建模之外的物理测试平台方面的有用性；(2)利用机器人实验的较短周期来产生最适合测试老鼠实验中特定假设的迷宫配置。

Spatial navigation is a complex cognitive process that relies on robust and adaptive mechanisms to relate current and future spatial positions to specific locations in the environment. The goal of this project is to provide a better understanding of spatial navigation by integrating information obtained from experimental studies in rats, computational models, and experiments on robots that will test new hypotheses on how these mechanisms work. The hippocampus and medial entorhinal cortex (MEC) are major brain regions involved in mammalian spatial navigation. While the role of place cells in the hippocampus has been extensively studied, there are still many open questions on the functional role of MEC grid cells and their interaction with the hippocampal place cells. Of interest to this proposal is the recent finding that grid cells are organized in an orderly fashion along the dorso-ventral axis of the MEC, with dorsal grids being much more tightly spaced than ventral ones. The investigators hypothesize that this multiscale organization endows the navigation system with a coding mechanism that will inherently achieve robustness with respect to external perturbations such as obstacles or unexpected changes in visual cues. In order to evaluate this hypothesis the investigators will develop computational and robotic models while systematically performing experiments in rat in which the dorsal or ventral portions of MEC or hippocampus will be inactivated. They will introduce new types of mazes in which the spatial frequency of the trajectories will be controlled. This work will contribute to better spatial navigation in robotics by: (1) providing a robotic testbed to evaluate hypotheses on the role of the entorhinal cortex and (2) providing biologically plausible models for robust spatial navigation under uncertain and dynamic environments. These models will suggest alternatives to classical probabilistic methods commonly used in robot Simultaneous Localization And Mapping paradigms. This work will also contribute to studies of spatial navigation in rats by: (1) showing the usefulness of robots in providing a physical testbed beyond pure computational modeling, and (2) exploiting the shorter cycle of robot experimentation to produce maze configurations that are optimal for testing specific hypotheses in rat experiments.