Multidimensional feature encoding and functional organization in the pigeon entopallium

Understanding how birds perceive and recognize objects remains a fundamental question in neuroscience. The entopallium, a key node in the avian tectofugal pathway, is involved in complex visual processing, yet its functional organization remains incompletely understood. Here, we systematically mapped entopallium neuronal responses in pigeons using controlled visual stimuli varying in color, shape, and motion. Entopallium neurons exhibited strong hue selectivity invariant to luminance, pronounced orientation tuning to shape stimuli, and robust direction selectivity to motion. Spatial analyses revealed distinct functional segregation, with color-selective neurons localized anteroventrally, shape-selective neurons dorsally, and motion-selective neurons posteriorly. Despite this segregation, a subset of neurons exhibited joint tuning across stimulus dimensions, suggesting an integrated yet modular organizational scheme. Notably, entopallium neurons exhibited a moderate level of feature integration, sharing key characteristics with early to intermediate stages of mammalian visual processing. Together, these findings establish the entopallium as a central hub for multidimensional visual processing in birds and provide new insights into the convergent evolution of sophisticated visual systems across vertebrates.