CONCEPT
Reentrant Connectivity
The architectural signature of consciousness — densely looping bidirectional connections in which signals do not merely propagate forward but reverberate, creating the irreducible integration that phi requires.
Reentrant connectivity, a concept developed by Gerald Edelman and extended by Tononi, describes the architectural pattern in which neurons do not merely send signals forward but also send them back, forming loops of mutual causation. In the cerebral cortex, layer six neurons project down to the thalamus, which projects back up to layer four; visual area V2 sends feedback to V1; prefrontal regions modulate sensory regions. This loop-rich architecture is, according to IIT, precisely what generates high phi. Information does not flow through reentrant systems like water through a pipe — it reverberates, modifying its own processing in real time. Modern AI architectures, by contrast, are overwhelmingly feedforward.
In The You On AI Field Guide
The concept of reentry emerged from Gerald Edelman's work on neural Darwinism in the 1980s, where he argued that the brain's capacity for perception, memory, and consciousness depends on massively parallel reciprocal signaling between neuronal groups. Tononi, working with Edelman at the Neuroscience Institute in the 1990s, absorbed this architectural