Influence of Proximal, Distal, and Vestibular Frames of Reference in Object-Place Paired Associate Learning in the Rat

Object-place paired associate learning has been used to test hypotheses regarding the neurobiological basis of memory in rodents. Much of this work has focused on the role of limbic and hippocampal-parahippocampal regions, as well as the use of spatial information derived from allothetic visual stimuli to determine location in an environment. It has been suggested that idiothetic self-motion (vestibular) signals and internal representations of directional orientation might play an important role in disambiguating between spatial locations when forming object-place associations, but this hypothesis has not been explicitly tested. In the present study, we investigated the relationship between allothetic (i.e., distal and proximal cues) and vestibular stimuli on performance of an object-place paired-associate task. The paired-associate task was composed of learning to discriminate between an identical pair of objects presented in 180° opposite arms of a radial arm maze. Thus, animals were required to select a particular object on the basis of spatial location (i.e., maze arm). After the animals acquired the object-place rule, a series of probe tests determined that rats utilize self-generated vestibular cues to discriminate between the two maze arms. Further, when available, animals showed a strong preference for local proximal cues associated with the maze. Together, the work presented here supports the establishment of an object-place task that requires both idiothetic and allothetic stimulus sources to guide choice behavior, and which can be used to further investigate the dynamic interactions between neural systems involved in pairing sensory information with spatial locations.物体-位置配对联想学习（Object-place paired associate learning）曾被用于检验关于啮齿类动物记忆神经生物学基础的各类假说。既往多数相关研究聚焦于边缘系统与海马-海马旁回区域的功能，并探讨了源自外源（allothetic）视觉刺激的空间信息在环境定位中的应用。已有研究提出，内源自身运动（idiothetic self-motion，即前庭）信号以及方向定向的内部表征，在形成物体-位置联想时对区分不同空间位置可能发挥关键作用，但该假说尚未得到明确验证。本研究中，我们探究了外源（即远端与近端线索）与前庭刺激对物体-位置配对联想任务作业绩效的影响。本研究采用的配对联想任务，要求动物学习辨别呈现在径向臂迷宫（radial arm maze）180°相对两臂内的一对相同物体，即动物需依据空间位置（即迷宫臂）来选择特定物体。待动物掌握物体-位置规则后，一系列探针测试结果显示，大鼠会借助自身产生的前庭线索来区分两个迷宫臂。此外，当存在相关线索时，动物会显著偏好与迷宫相关的局部近端线索。综上，本研究构建的物体-位置任务需同时依赖内源与外源刺激源来指导选择行为，可用于进一步探究将感觉信息与空间位置进行配对的神经系统之间的动态交互机制。