Conscious awareness is not exclusive to mammals with a layered cerebral cortex. Neurophysiological recordings in crows show a neuronal correlate of consciousness in the pallial endbrain, a structure that develops from different embryonic territories and lacks the layered architecture of the mammalian cortex. This suggests that the mammalian cerebral cortex is not necessary for consciousness to emerge across vertebrates. Instead, the telencephalic pallium, with its specific anatomical and physiological principles, appears to serve as a brain substrate that can independently give rise to conscious experience in different vertebrate lineages.
Neuronal activity in the pallial endbrain of carrion crows correlates with their perception of a visual stimulus, suggesting that sensory consciousness can arise in brains without a layered cerebral cortex. Single-neuron responses during a detection task show a two-stage temporal process: an early component reflecting physical stimulus intensity and a later component predicting the birds' perceptual reports. The authors argue this is an empirical marker of avian consciousness, indicating that the neural foundations for sensory consciousness either emerged before mammals or evolved independently in birds.