Abstract
In the first of two companion papers, we argued that classical neural mechanisms proposed to implement conscious active inference had failed to establish their biological plausibility in terms of realistic biophysical models. We further explained that conscious (temporally deep) active inference is mathematically equivalent to the path integral that underlies quantum dynamics. As such, we proposed that a quantum model provides a natural, biologically plausible mechanistic implementation of the processing required by active inference. In this second paper we review the evidence establishing discrete non-overlapping cycles of perceptual inference, and argue that classical process models have so far failed to motivate or describe these discrete cycles in terms of realistic neural mechanisms. We then point out that the Orchestrated Objective Reduction (Orch OR) theory of consciousness naturally solves this fundamental problem. Along the way, we review independent strong theoretical and experimental evidence from my (Wiest) lab and others' supporting the Orch OR quantum theory of consciousness as a collective quantum property of intraneuronal microtubules (MTs). This includes demonstration of room-temperature quantum effects in MTs, MT resonances controlling membrane spiking in living neurons, evidence that volatile anesthetics target MTs to cause unconsciousness, and direct biophysical evidence of a macroscopic entangled state in the living human brain. Intraneuronal MTs thus offer a biologically specific and experimentally supported substrate for implementing conscious active inference in brains.