|In our model, quantum coherence emerges, and is isolated,
in brain microtubules until the differences in mass-energy distribution
among superposed tubulin states reach the threshold of instability
described above, related to quantum gravity (Figure 6). The resultant
self-collapse (OR), considered to be a time-irreversible
process, creates an instantaneous "now" event. Sequences
of such events create a flow of time, and consciousness (Figures 7
We envisage that attachments of MAPs on microtubules "tune" quantum oscillations, and "orchestrate" possible collapse outcomes (Figure 9). Thus we term the particular self-organizing OR occurring in MAP-connected microtubules, and relevant to consciousness, orchestrated objective reduction ("Orch OR"). Orch OR events are thus self-selecting processes in fundamental space-time geometry. If experience is truly a component of fundamental space-time, Orch OR may begin to explain the "hard problem" of consciousness.
Summary of the Orch OR Model for Consciousness
The full details of this model are given in Hameroff and
Penrose (1996). The picture we are putting forth involves the following
The Orch OR model thus appears to accommodate some important features of consciousness:
|Conclusion: What is it like
to be a worm?
The Orch OR model has the implication that an organism able to sustain quantum coherence among, for example, 10^9 tubulins for 500 msec might be capable of having a conscious experience. More tubulins coherent for a briefer period, or fewer for a longer period (E = h bar / T ) will also have conscious events. Human brains appear capable of, for example, 10^11 tubulin, 5 msec "bengal tiger experiences," but what about simpler organisms?
From an evolutionary standpoint, introduction of a dynamically functional cytoskeleton (perhaps symbiotically from spirochetes, e.g. Margulis, 1975) greatly enhanced eukaryotic cells by providing cell movement, internal organization, separation of chromosomes and numerous other functions. As cells became more specialized with extensions like axopods and eventually neural processes, increasingly larger cytoskeletal arrays providing transport and motility may have developed quantum coherence via the Fröhlich mechanism as a by-product of their functional coordination.
Another possible scenario for emergence of quantum coherence leading to Orch OR and conscious events is "cellular vision." Albrecht-Buehler (1992) has observed that single cells utilize their cytoskeletons in "cellular vision" - detection, orientation and directional response to beams of red/infra-red light. Jibu et al (1995) argue that this process requires quantum coherence in microtubules and ordered water, and Hagan (1995) suggests the quantum effects/cellular vision provided an evolutionary advantage for cytoskeletal arrays capable of quantum coherence. For whatever reason quantum coherence emerged, one could then suppose that, one day, an organism achieved sufficient microtubule quantum coherence to elicit Orch OR, and had a "conscious" experience.
At what level of evolutionary development might this primitive consciousness have emerged? A single cell organism like Paramecium is extremely clever, and utilizes its cytoskeleton extensively. Could a paramecium be conscious? Assuming a single paramecium contains, like each neuronal cell, 10^7 tubulins, then for a paramecium to elicit Orch OR, 100% of its tubulins would need to remain in quantum coherent superposition for nearly a minute. This seems unlikely.
Consider the nematode worm C elegans. It's 302 neuron nervous system is completely mapped. Could C elegans support Orch OR? With 3 x 10^9 tubulins, C elegans would require one third of its tubulins to sustain quantum coherent superposition for 500 msec. This seems unlikely, but not altogether impossible. If not C elegans, then perhaps Aplysia with a thousand neurons, or some higher organism. Orch OR provides a theoretical framework to entertain such possibilities.
Would a primitive Orch OR experience be anything like ours? If C elegans were able to self-collapse, what would it be like to be a worm? (Nagel, 1974) A single, 10^9 tubulin, 500 msec Orch OR in C elegans should be equal in gravitational self-energy (and thus perhaps, experiential intensity) to one of our "everyday experiences." A major difference is that we would have many Orch OR events sequentially (up to, say, 10^9 per second) whereas C elegans could generate, at most, 2 per second. C elegans would also presumably lack extensive memory and associations, and have poor sensory data, but nonetheless, by our criteria a 10^9 tubulin, 500 msec Orch OR in C elegans would be a conscious experience: a mere smudge of known reality, the next space-time move.
Consciousness has an important place in the universe. Orch OR in microtubules is a model depicting consciousness as sequences of non-computable self-selections in fundamental space-time geometry. If experience is a quality of space-time, then Orch OR indeed begins to address the "hard problem" of consciousness in a serious way.
Reprinted from Journal of Consciousness Studies (2)1:36-53, 1996