An answer to an elusive mystery of consciousness?
Newly-discovered quantum dot-like structures in neural tissue could provide a global workspace function.
Many people are surprised to learn that the physical mechanism that is responsible for the human experience of consciousness has not yet been discovered. While it is possibly undisputed that some portion of the 80 billion or so neurons in the average human brain are associated with that experience, it is also known that those neurons are involved in both somatic and autonomic functions. The somatic functions result in conscious actions; the autonomic functions (like breathing and heart beats) have limited or no conscious control. What makes some of these neurons part of the conscious experience, and others not?
In addition, it is also known that some neurons are involved in subconscious processes, but can switch over and become part of conscious processes. For example, hidden words or shapes in images are processed by neurons, but can elude conscious awareness until discovered or identified. The reason why is not presently known.
However, a recent discovery could explain at least some of these phenomena. Certain neural tissues are known to have high concentrations of ferritin (an iron storing protein) and neuromelanin. The function of neuromelanin is unclear, unlike the function of ferritin. However, in the field of solar photovoltaic (PV) devices, quantum dot arrays have been shown to conduct electric energy at room temperature using quantum mechanical “electron transport,” and the size and distribution of ferritin and neuromelanin in these neural tissues is similar to the size and distribution of quantum dots in those PV devices. But can they conduct electric energy using electron transport?
In recent tests of human neural tissue, the presence of such electron transport has been observed. Atomic force microscopy (AFM) uses a cantilever probe, like a see-saw, which is used to measure the height of surface features of a sample. Because the probe is very small, it can measure surface feature dimensions that are in the nanometer range — one billionth of a meter. For comparison, if the distance between the earth and the moon was one meter, then one nanometer would be a little over one foot. In conductive AFM (c-AFM), a voltage is applied to the probe tip, and currents are measured to determine the electrical properties of the sample.
In these tests, electrons were shown to flow from a grounded neural tissue sample into a negatively biased c-AFM probe, as shown in the data graphic below:
As can be seen, the majority of these current measurements are positive, which represents current flowing into the negatively biased c-AFM probe tip. These currents are the opposite of what should happen — the electrons in the negative probe tip should have flowed out of the probe tip into the grounded sample, which is what would be expected from classical electron behavior. A control sample was also tested, and such classical behavior was observed in that sample as shown below:
As can be seen, these currents are negative, which is the expected behavior of current from a negative c-AFM probe tip voltage. The behavior of electrons in regions containing ferritin and neuromelanin is like trying to pour a glass of milk from a carton, but instead having milk spontaneously appear in the glass and leap into the carton! Such “non-classical” electrical effects can be explained using principles of quantum mechanical electron transport.
While these tests need to be duplicated and verified, the hypothesized mechanism that is consistent with and predicted these test results is similar to key aspects of many consciousness theories, such as the global workspace theory proposed by Dr. Bernard Baars in 1988, or the centrencephalic theory first proposed by Penfield and Jasper in the 1950s.
The neural tissues where these quantum dot-like structures are found include the substantia nigra pars compacta (SNc), part of the basal ganglia that controls the activation of voluntary or conscious actions. Based on the results of the c-AFM tests, it is possible that electrons that are transported in these quantum dot structures are coherent, or wave-like, and may interact with each other in a manner that contributes to the creation of the conscious experience. For example, the electrons could store “state” information that is related to the neural signals being received by the neurons of the SNc, and the integration of this neural state information by the coherent electrons could be directly related to the conscious experience. This mechanism would explain why some neurons are never part of the conscious experience (if they never connect to these neural tissues), and why others are sometimes in and sometimes out (depending on whether they are activated sufficiently to contribute coherent electron state information).
There are many unanswered questions, though. One question is how the chemical and electrical signals received at each of the hundreds of thousands or even millions of neurons that are associated with these neural tissues translate into what amounts to a hallucination, albeit one that correlates closely to the real world around us. For an excellent explanation of this process, see: https://ed.ted.com/featured/tW13nXiE. Another question is how neural tissues in different regions of the brain that have these quantum dot-like structures could interact with each other to create the singular experience of conscious, although that could be a result of identical synchronized neural inputs into those different neural tissues.
Answering these questions will take substantial additional research, but could result in ways to control physical sensations without drugs or other stimuli. Pain and depression might be able to be turned off, anger and rage might be able to be negated or damped, and new sensory inputs might be able to be created. An amputee might be able to feel a prosthetic limb as if it were a real limb, instead of more limited existing prosthetic controls that are similar to using a man-machine interface like a mouse or keyboard. New sensory experiences might also be possible, such as the ability see radio waves — not mapped to the visible light spectrum but rather as a new type of sensory experience that is distinct from the experience of seeing visible light.
Conclusion
While the results of these tests are consistent with predictions that are based on the presence of quantum dot-like ferritin and neuromelanin structures in neural tissue, they do not prove the hypothesis of associated neural function that provided those predictions. Given the persistent skepticism towards quantum biology by many in the scientific community (despite its growing acceptance by many others), it will likely be at least several years before independent testing is performed to validate these test results, much less to address that broader hypothesis.
References:
Rourk, C. J. (2018, September 1). Ferritin and neuromelanin “quantum dot” array structures in dopamine neurons of the substantia nigra pars compacta and norepinephrine neurons of the locus coeruleus. BioSystems. Elsevier Ireland Ltd. https://doi.org/10.1016/j.biosystems.2018.07.008
Rourk, C. J. (2019). Indication of quantum mechanical electron transport in human substantia nigra tissue from conductive atomic force microscopy analysis. Biosystems. https://doi.org/10.1016/j.biosystems.2019.02.003
