Adele J. Kapellusch’s research while affiliated with McKnight Brain Institute and other places

Background Our understanding of the neural systems that subserve navigation and spatial processing can be greatly improved through access to experimental approaches that allow for precise spatial and temporal control of the sensory information that inform these systems. Furthermore, paradigms that incorporate concurrent behavioral metrics of navigation performance in the presence of experimental manipulations provide an additional dimension in which to understand neurobiological findings. New method We investigate the use of a novel behavioral apparatus, the Instantaneous Cue Rotation (ICR) arena, which utilizes an augmented reality system to allow for rapid remote control of all symmetry breaking visual cues in the environment as rats perform a real-world visual cue-based navigation task. Results We present behavioral data collected using two different reward delivery systems (fixed or mobile). Rats’ behavior was assessed with respect to the degree and timing with which their navigation strategies changed in response to an instantaneous rotation of all orienting visual cues in the arena. We show that rats were able to utilize projected visual cues to navigate to a cue-aligned goal both before and after the cues were rotated, and that the mobile feeder version was optimal. Comparison with existing methods In contrast to commonly used existing approaches for investigating environmental cues in spatial processing, the ICR does not require interrupting ongoing navigation behavior or rely on virtual reality systems that limit self-motion feedback. Conclusions The ICR is an effective new method for dissociating the role of self-motion and environmental cues in navigation.

Young and aged animals were tested on a spatial alternation task that consisted of two interleaved components: (1) an “outbound” or alternation component (working memory) and (2) an “inbound” component, requiring the animal to remember to return to a central location in space (spatial memory). In the present study, aged rats made more outbound errors throughout testing, resulting in significantly more days to reach learning criterion, as compared to young rats. Furthermore, while all animals were able to learn the hippocampus-dependent inbound component of the task, most aged animals remained just above chance on the outbound component, even after extended testing days. Aged rats may be more impaired on the outbound part of the task because it requires cooperation of both the hippocampus and mPFC, each of which is compromised with age. In addition to presenting these results, we compare one commonly used analysis (repeated measures ANOVA) and two less common hierarchical modeling techniques (hierarchical generalized linear model and state-space random effects model) to determine the best method for comparing population learning over time. We found that hierarchical modeling is the most appropriate for this task and that a state-space model better captures the behavioral responses.