Lewis and MacGregor’s Phase of Energy Resonator Model

Bioengineers Edwin R. Lewis and Ronald J. MacGregor propose an energy-based resonator model of consciousness, “a two-way exchange of energy between the conscious mental realm and the physical realm of the brain.” They draw “an analogy between the mental and physical phases of energy and the phases (e.g., gas/liquid) of matter, and a possible realization in the form of a generic resonator.” As candidate substrates of such a system, they favor astroglial-pyramidal cell and electromagnetic-field models (Lewis & MacGregor, 2010).

Evolutionary Basis and Two-Way Street

Synthesizing evolutionary biology, cognitive neuroscience, and systems-level neurophysiology, Lewis and MacGregor assume that consciousness arose through natural selection, meaning it must be: physically instantiated (i.e., based in matter and energy), selectable (must have a phenotype), and functionally advantageous. “Accepting an evolutionary basis of consciousness… we would be compelled to accept the premise that awareness, in itself… must be a causative agent capable of modulating physical activity.”

This leads to the necessity of a two-way interaction between the mental realm (M) and the physical brain (P)—what they call a “two-way street.” This is the only way, they argue, for consciousness to influence behavior (and hence be selectable by evolution): it must exert some causal influence on the brain. In their form,

P → M: Neural activity gives rise to mental states (e.g., perceptions and feelings).

M → P: Mental states causally influence neural activity (e.g., directing attention or inhibiting action—what they call “free won’t”).

“The nature of that two-way street is the 21st century’s mystery of mysteries, the ‘explanatory gap’… along one side (P → M)… along the other side (M → P)…” (Lewis & MacGregor, 2010).

Dispositional Energy and Phase Analogy

In their most distinctive theoretical move, the authors speculate that this two-way interaction involves a two-way exchange of energy, which they call dispositional energy—a putative novel form of energy available to consciousness for transfer of information along the M → P side of the street and required to account for the M → P effect.

They liken dispositional energy to a “phase of energy,” similar to how water changes state: “We see the generation and maintenance of dispositional energy as dependent on particular molecular processes… We picture consciousness and dispositional energy as emerging and rising beyond their traditional physical energy origins somewhat as vapors rise beyond their warming liquid forms.”

Energy being a physical entity, the authors consider it to be strictly confined to the physical realm (P), such that they imagine “the action of consciousness as gating or modulating the flow of energy between various locales in P. Any process of gating, however, requires expenditure of at least some energy on the part of the gatekeeper.” This seems to require at least a modicum of energy to be associated with M itself. “This would be the dispositional energy. And it would be this (information-bearing) energy that flows along the lanes of the M → P side of the street.”

Dispositional Energy and Phase Analogy

The authors seek, then, “a form of energy that can be set aside and then transferred quickly over the brain.” One such form, they say, is the energy of resonance. “Spatially separated resonators tuned close to a common frequency tend to phase lock and share energy. This is accomplished through a field, such as a vibration field in an old-fashioned clock shop, or an electric field for electrical resonances” (Lewis & MacGregor, 2010).

Thus, to model the two-way interaction mechanistically, the authors introduce the ‘resonator model of consciousness.’ These are hypothesized molecular or cellular structures (e.g., astroglial–pyramidal cell interfaces) that: generate mental states via transformation of neural energy into dispositional energy (P → M), allow for coupling among resonators (M M), and effect causal changes in the brain (M → P). “All resonator elements produce P → M transformation and engage in collective partially-free M–M selections… some may produce lesser or no M → P transformation.”

To Lewis and MacGregor, their model is both metaphor and scientific hypothesis: dispositional energy may represent a phase of matter/energy that is partially exempt from deterministic laws, thereby enabling partial freedom (agency).

Biological Substrate Hypothesis

As a candidate physical substrate, Lewis and MacGregor prefer the astroglial–pyramidal cell interface, where astrocytes regulate metabolite flow to cortical pyramidal neurons, and they hypothesize that Krebs cycle activity in astrocytes may be a source of dispositional energy. “Our favored complete working hypothesis is that resonator elements are found as mitochondrial catalysts of the Krebs ATP cycle in astrocytes of the astroglial–pyramidal interface of the eocortex” (Lewis & MacGregor, 2010).