Reeler mice show impaired performance in a texture-based novelty recognition task

During cortical development, reelin, a glycoprotein primarily expressed and secreted by Cajal-Retzius cells in the marginal zone, plays a fundamental role in guiding newborn neurons' migration and thereby organizing proper layering of the cortex. Thus, Reeler mice, naturally occurring mutants with a complete reelin deficiency, are characterized by disrupted cortical development with extensive neuronal disorganization, which may profoundly alter its functionality. Interestingly, the overall composition of neuron types and the proportional ratio of excitatory to inhibitory neurons is similar to wild type (WT) mice and our previous investigations have unveiled the presence of barrel-like clusters and columns within the disordered and unlayered somatosensory (barrel) cortex of Reeler mice. Although Reeler mice were tested previously in multiple behavioral paradigms, the capacity of the Reeler cortex to perform appropriately in a tactile task remained uninvestigated. In this study, we have compared the tactile discrimination capacity of Reeler and WT mice with a novel texture recognition paradigm. Group comparisons revealed that while WT mice were able to recognize the novel texture, Reeler mice showed variable performance on this task and failed to recognize the novel texture, despite cell types and local circuits being largely intact in this mutant. These results suggest a dissociation between preserved local circuitry and impaired sensory processing.