Measuring locomotor strategies of freely moving previsual rat pups
Inna S Midzyanovskaya1, Vasily V Strelkov2
1Institute of Higher Nervous Activity and Neurophysiology of Russian Academy of Sciences, 5A Butlerova St., Moscow 117485, Russia.
Insights
Previsual rat pups navigate using non-visual cues, exhibiting distinct locomotion patterns. Localized walks show sub-diffusive behavior, suggesting re-attraction, while raids indicate an escape response.
Area of Science:
- Neuroscience
- Animal Behavior
- Locomotion Analysis
Background:
- Previsual rat pups navigate using non-visual sensory modalities.
- Understanding early-life navigation strategies is crucial for developmental neuroscience.
Purpose of the Study:
- To analyze the locomotion patterns and navigational strategies of previsual rat pups in an open field.
- To differentiate between random and strategic components in early-life movement.
Main Methods:
- Tracking the movements of 13-day-old Wistar rat pups (n=51) in an open field test for 2 minutes.
- Applying a space potentials method for automated segmentation of movement tracks.
- Analyzing velocity autocorrelation functions to understand trajectory dynamics.
Main Results:
- Three distinct locomotion patterns were observed: localized sub-diffusive walks, quasi-linear escape raids, and mixed strategies.
- Localized walks were random at short timescales (<2-3s) but sub-diffusive (non-random) at longer scales, attributed to trajectory re-attraction.
- Quasi-linear raids were identified as a primary active escape response.
Conclusions:
- Previsual rat pups employ complex, non-random navigational strategies beyond simple diffusion.
- Self-odor traces may serve as physical cues for trajectory re-attraction during localized walks.
- Locomotion patterns reflect distinct behavioral responses, including exploration and active escape.
Abstract:
Blind walks of previsual rat pups in the open field test were analyzed for random components and/or strategies of locomotion. Wistar infants (n = 51) on their 13th postnatal day was tracked in the open field test for 2 minutes. At this age, immature rats should rely only on non-visual modalities in their navigation. Three distinct patterns were observed. A large portion of the pups (n = 22) performed sub-diffusive localized walks in the center. A smaller cohort (n = 9) undertook almost immediate quasi-linear raids in a random direction, thus succeeded in reaching a shelter (i.e., walls' vicinity). The rest (n = 20) demonstrated a mixed strategy: localized walks interspersed with quasi-linear raids. We applied a method of space potentials for an automated segmentation of the tracks into the localized walks and quasi-linear fragments. We found that the localized walks were random only for the time scale below 2-3 seconds, but essentially non-random (sub-diffusive) for longer scales. The sub-diffusion was caused by the trajectories' re-attraction, as seen from the averaged velocity autocorrelation function. Self-odor traces can be a physical cue ensuring the trajectorial returns. Oppositely, the quasi-linear raids can be considered a primary form of an active escape response.
