by Danielle Graham: In the introduction of his book Iconoclast…
Emory neurologist and neuroeconomist Gregory Berns makes the statement “the brain has a fixed energy budget.” Later, he explains that his current understanding of the brain’s use of energy is largely based on a theory that presumes the human brain has reached a certain culmination of functionality. Berns references Nobel Laureate (in immunology) Gerald Edelman’s decades old theories of “neural Darwinism … principals of resource competition and adaptation.” Though I agree that the human brain has evolved and will continue to do so, there is little evidence to show that our neurological evolution has reached any kind of pinnacle. Certainly, if human brain function and energy consumption have progressed by continuously adapting to conserve energy expenditure, then it is logical to assume that our understanding of these neurophysiological processes will only continue to evolve and that scientists will surrender theories that are no longer viable for ones that incorporate a greater understanding.
Despite the fact that scientists specializing in neurological discovery have generated a significant body of research evidence and have contributed towards a developing understanding of neural structure and how those structures perform tasks (function), comprehensive models that account for some of our most fundamental human experiences have yet to emerge. [For instance, a scientific understanding that encompasses the relationship between a person’s brain and their conscious awareness continues to elude scientists.] New and exciting neurological research is being published daily from labs all over the world and not only in neurologically or psychologically related journals, but in various engineering, chemical, and physics journals as well. The collective neurological knowledge base is rapidly expanding to incorporate and integrate research information obtained from separate but related fields of study. This broadening scope of generated research evidence will continue. As it does, what neurologists had previously considered as “the brain functioning on limited energy resources,” may very well progress to show that the human brain is connected to unlimited resources of energy. Today, however, those resources, just like the biological correlation of conscious awareness, have yet to be scientifically realized.
The brain is not an island; it is the center of our nervous system, directly and indirectly exchanges information with every cell in the body, and floats in a sack of protein and mineral rich isotonic solution called cerebrospinal fluid (CSF). Researchers have only recently determined the electrical conductivity of CSF at body temperature to be 44% and higher than previously recognized, simply because past measurements were obtained at room temperature from fluids sitting in a petri dish. If valid energy conductance levels in CSF correlate with live body temperature, the brain’s energy metabolism functions must also be measured while the central nervous system is in vivo – alive – for greater accuracy as well. Both of these instances show the importance and necessity of generating data from “living” human beings so as to collect better and more accurate information on all the many parts that combine to form our neurological systems.
There is no longer any argument that our brains provide a functionality that is greater than the mere sum of its components (proteins, protein building amino acids, water, etc.) Therefore, any kind of premise built exclusively on reductionistic thinking does not realistically serve the process of building comprehensive neurological models. Knowledge that is being gathered in a broad spectrum of disciplines by the scientists exploring the mysteries of the brain must accurately mirror the conditions of a functioning brain. Fortunately, many of the newer technologies used for neurological study require that the subject be both alive and conscious enough to perform repetitive tasks.
Scanners, such as functional Magnetic Resonance Imaging machines (fMRI) track energy movement in the brain by measuring the hemodynamic response (blood flow). Neurons in the brain require significant amounts of energy to perform their tasks and this energy is supplied in the form of glucose and oxygen which is regulated by demand; when neurons become active, blood flow is directed to that specific location. fMRI technology is then able to capture pictures of the brain’s energy use as the blood flow carries oxygen rich hemoglobin (red blood cells) to the parts of the brain requiring that energy.
Understanding how specific thoughts trigger the need for energy along specific neurons paths, those thoughts can then be associated with specific areas of he brain. With proper protocols and controls in place, research using fMRI and other similar technologies can provide great insights into how a living brain both functions and consumes energy.