The Brain Is Both Neurocomputer and Quantum Computer


Departments of Anesthesiology and Psychology, University of Arizona Health Sciences Center, 1501 N. Campbell Ave., Room 5301, Tucson, AZ, 85724. E-mail:


In their article, Is the Brain a Quantum Computer,?Litt, Eliasmith, Kroon, Weinstein, and Thagard (2006) criticize the Penrose–Hameroff “Orch OR” quantum computational model of consciousness, arguing instead for neurocomputation as an explanation for mental phenomena. Here I clarify and defend Orch OR, show how Orch OR and neurocomputation are compatible, and question whether neurocomputation alone can physiologically account for coherent gamma synchrony EEG, a candidate for the neural correlate of consciousness. Orch OR is based on quantum computation in microtubules within dendrites in cortex and other regions linked by dendritic–dendritic gap junctions (“dendritic webs”) acting as laterally connected input layers of the brain's neurocomputational architecture. Within dendritic webs, consciousness is proposed to occur as gamma EEG-synchronized sequences of discrete quantum computational events acting in integration phases of neurocomputational “integrate-and-fire” cycles. Orch OR is a viable approach toward understanding how the brain produces consciousness.