Consciousness without cortex.

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.

Study at a glance

Abstract

Sensory consciousness - the awareness and ability to report subjective experiences - is a property of biological nervous systems that has evolved out of unconscious processing over hundreds of millions of years. From which brain structures and based on which mechanisms can conscious experience emerge? Based on the body of work in human and nonhuman primates, the emergence of consciousness is intimately associated with the workings of the mammalian cerebral cortex with its specific cell types and layered structure. However, recent neurophysiological recordings demonstrate a neuronal correlate of consciousness in the pallial endbrain of crows. These telencephalic integration centers in birds originate embryonically from other pallial territories, lack a layered architecture characteristic for the cerebral cortex, and exhibit independently evolved pallial cell types. This argues that the mammalian cerebral cortex is not a prerequisite for consciousness to emerge in all vertebrates. Rather, it seems that the anatomical and physiological principles of the telencephalic pallium offer this structure as a brain substrate for consciousness to evolve independently across vertebrate phylogeny.