Bandyopadhyay Microtubule Conductance

Bandyopadhyay Microtubule Conductance

Audience

Difficulty	Intermediate

Notation on this page

The Bandyopadhyay microtubule conductance experiments are a series of measurements by Anirban Bandyopadhyay and collaborators at the National Institute for Materials Science (NIMS, Tsukuba, Japan), beginning around 2011 and continuing through the 2020s. The experiments use single-molecule electrical-transport techniques to measure the electronic conductance of single microtubules at room temperature.

The reported results are striking: microtubules exhibit anomalously high DC and AC conductance, with sharp resonant frequency peaks in the kHz–THz range, behaviour that is inconsistent with standard biological-polymer models and consistent with quantum-coherent electronic transport along the microtubule lattice.

If confirmed by independent groups at high precision, these results would provide a significant empirical foundation for the Orch OR proposal and for the framework's microtubule substrate for ψ-coupling.

Experimental setup

The Bandyopadhyay group's experiments use:

• Single-molecule conductance measurement — a single microtubule (~ 25 nm diameter, length variable from ~ 100 nm to several μm) bridged between two nanopatterned electrodes.
• Room temperature, aqueous environment — to ensure biological relevance.
• Frequency sweep — AC conductance measured across many decades of frequency, from DC up to ~ THz.
• Multiple microtubule preparations — isolated brain microtubules, in vitro reconstituted microtubules from purified tubulin, and microtubules with various drug treatments.

Key results

Anomalously high conductance

DC conductance of single microtubules is reported at levels many orders of magnitude higher than would be expected for a biological insulator or weakly-conducting polymer. Reported values are consistent with quasi-metallic electronic transport along the lattice.

Sharp frequency-resonance peaks

AC conductance shows sharp resonant peaks at specific frequencies in the kHz, MHz, GHz, and THz ranges. The reported peak frequencies include:

• Slow (~ kHz): coupling to ionic motions and slow conformational modes.
• Intermediate (~ MHz): coupling to dielectric-relaxation modes.
• Fast (~ GHz–THz): coupling to electronic and tubulin-orientational modes; particular peaks reported at ~ 14 MHz, 250 MHz, 8 GHz, 200 GHz.

The peaks are sharp (high Q-factor), suggesting underlying coherent oscillator modes rather than broadband dielectric loss.

Coherence and lattice-length dependence

Conductance peaks scale with microtubule length in ways consistent with coherent transport along the lattice. The reported behaviour does not match a simple Ohmic resistor model.

Drug-modulated behaviour

Treatments with anaesthetics, microtubule-stabilising agents (taxol), and microtubule-destabilising agents (vinblastine, colchicine) modulate the measured conductance in ways consistent with the lattice integrity being central to the coherent transport.

Theoretical interpretation

Several interpretations have been advanced:

1. Quasi-1D quantum-coherent transport along the microtubule's helical pattern of aromatic-residue chromophores.
2. Tubulin-orientation coupled vibronic states — coupled electronic-vibrational modes in tubulin dimers.
3. Ordered-water lumen as a coherent dielectric medium supporting electronic states differently from bulk water.
4. Collective superradiance — see Celardo_Microtubule_Superradiance for the theoretical proposal that aromatic-residue arrays produce coherent emission with characteristic frequency peaks.

None of these is yet a settled, quantitative theory; each is consistent with the observed behaviour but does not yet predict the specific peak frequencies.

Replication status

The Bandyopadhyay group has published the results in multiple peer-reviewed journals:

• Sahu, S., et al. (2013). "Atomic water channel controlling remarkable properties of a single brain microtubule." Biosensors and Bioelectronics 47: 141–148.
• Sahu, S., Ghosh, S., Hirata, K., Fujita, D., Bandyopadhyay, A. (2013). "Multi-level memory-switching properties of a single brain microtubule." Applied Physics Letters 102: 123701.
• Additional papers in Journal of Integrative Neuroscience, Journal of Biomolecular Structure and Dynamics, and conference proceedings.

Independent replication of the specific frequency-resonance peaks at the precision reported by Bandyopadhyay has been limited. Some replication-type work has been done but with somewhat different methodologies; clean independent confirmation is not yet established at the level required for full scientific consensus.

The challenges to replication:

• Single-molecule conductance with the specific nanopatterned-electrode geometry is technically demanding.
• Microtubule preparation protocols vary across labs.
• AC conductance measurements across many frequency decades require specialised instrumentation.

Multi-laboratory replication is one of the highest priorities for empirical psi-substrate research. See Open_Questions_in_Psionics.

Status in the framework

In the psionic framework, the Bandyopadhyay results — if confirmed — provide empirical support for:

• Microtubules as a quantum-coherent electronic substrate — consistent with the framework's prediction that microtubule electronic states couple to ψ via the αψ F_μν F^μν vertex.
• Specific frequency peaks — predictions of which discrete oscillator modes contribute to ψ-coupling. The framework does not yet predict the specific peak frequencies, but they constitute observable signatures.
• Substrate-level confirmation of Orch OR — without confirming the gravitational-OR mechanism, the results support the broader picture that microtubules are an unusual electronic system relevant to cognition.

The framework is not dependent on the Bandyopadhyay results being fully confirmed; the broader collective-neural-oscillation substrate (substrate 1 in Biological_Substrate_of_Psi) is robust. But if Bandyopadhyay is right, the microtubule contribution is substantial.

Sanity checks

• Microtubule depolymerisation → loss of conductance peaks. Reported. ✓
• Above body temperature (heat denaturation) → loss of conductance peaks. Reported. ✓
• Bulk-water environment without microtubule → no conductance peaks. ✓
• ψ → 0 (in framework) → microtubule conductance peaks may still exist via standard quantum-biology mechanisms. ✓ (Sanity_Check_Limits §12.)

Open questions

1. Quantitative prediction of the specific peak frequencies from first principles.
2. Independent multi-lab replication at the precision required for full acceptance.
3. Direct biological-function tests: do the conductance peaks correlate with cognitive states in vivo?
4. How does the conductance scale with microtubule length, lattice perfection, and post-translational modifications?

See Open_Questions_in_Psionics.

See Also

• Microtubule
• Orchestrated_Objective_Reduction
• Celardo_Microtubule_Superradiance
• Kalra_Anaesthetic_Microtubule
• Tegmark_Critique_and_Hagan_Rebuttal
• Anirban_Bandyopadhyay
• Biological_Substrate_of_Psi
• Famous_Experiments

References

• Sahu, S., Ghosh, S., Hirata, K., Fujita, D., Bandyopadhyay, A. (2013). "Multi-level memory-switching properties of a single brain microtubule." Applied Physics Letters 102: 123701.
• Sahu, S., et al. (2013). "Atomic water channel controlling remarkable properties of a single brain microtubule: Correlating single protein to its supramolecular assembly." Biosensors and Bioelectronics 47: 141–148.
• Ghosh, S., Aswani, K., Singh, S., Sahu, S., Fujita, D., Bandyopadhyay, A. (2014). "Design and construction of a brain-like computer: A new class of frequency-fractal computing using wireless communication in a supramolecular organic, inorganic system." Information 5: 28–100.
• Bandyopadhyay, A. (2021). Nanobrain: The Making of an Artificial Brain from a Time Crystal. CRC Press.