Tactile Sensory Deprivation Impairs Spatial Behavior in Previsual Rat Pups

The vibrotactile system provides essential sensory input for early behavior in previsual rat pups. To examine its role in spatial navigation, we conducted bilateral vibrissectomy or sham procedures on postnatal day (PND) 9–12 in 42 previsual pups (4 litters, balanced groups). Open-field testing on PND 13 showed that while vibrissectomy (VE) did not alter gross locomotor parameters (distance traveled, speed, acceleration, or freezing episodes; all p > 0.05), it significantly modified spatial behavior. VE pups explored a smaller percentage of the arena area (p = 0.01). We analyzed trajectorial compaction in the central zone (lacking wall tactile support) by smoothing trajectories with virtual coatings scaled to vibrissal length (16 mm). Individual references were generated for each track through linearization and identical smoothing. The compaction ratio, calculated as the ratio between the coated areas of linearized reference and experimental tracks, was significantly higher VE pups compared to sham controls (p = 0.03). No significant group difference was observed in path lengths within the central zone. This effect persisted when smoothing scales increased 2–3 fold (32–64 mm radii, approximating body size), but not at smaller scales (2–4 mm). These findings indicate that vibrissal input regulates spatial rather than locomotor components of previsual behavior. The simple open-field measures (area coverage, track compaction) thus serve as sensitive biomarkers for assessing vibrissal function in developing rodents. This study underscores the organizational role of tactile inputs in early spatial navigation and establishes a translatable hallmark for investigating sensory-guided behavior in neurodevelopment.