The sensory representation in the brain's primary areas relies on intricate anatomical and functional mapping, particularly evident in rodents where facial somatosensory territories have dedicated cortical maps for precise sensory processing. In the mouse primary somatosensory cortex (S1), mystacial and upper lip whiskers are processed in the postero-medial barrel subfield (PMBSF) and antero-lateral barrel subfield (ALBSF), respectively. PMBSF barrels are known for their size and high-resolution mapping, while ALBSF barrels are smaller and less defined. Traditionally, these differences in whisker size were believed to determine distinct levels of map sensitivity; however, recent findings challenge this perspective. Studies on blind mice demonstrate that thalamic calcium waves can modify cross-modally cortical barrel size, suggesting the capacity of intrinsic programs to enhance sensory map resolution early in life. To gain insights into the rules governing map resolution, we developed a mouse model, where the whisker pad containing mystacial whiskers is unilaterally cauterized during the embryo stage (embWPC). Using this model, we observed enhanced functional and anatomical resolution in the ALBSF without altering the size of upper lip whiskers. These alterations, guided by adjustments in transcriptional signatures and spontaneous activity patterns in the thalamus, emphasize the presence of a prenatal window during which the shaping of cortical barrel size and resolution occurs within developmental sensory maps.