These receptors encode only a single variable, light intensity—similar to an old-fashioned black-and-white TV. So this makes these forms of light medicine intrinsically achromatic—without color.
(…) To understand and appreciate the value of chromotherapy, one must take into account the whole optical system, including the visual optic pathway, that which is the most capable of perceiving color. And one must recognize that the perception of color is not purely a physiological phenomenon; it is also cognitive, and consequently it affects the mind as well as the body. Furthermore, chromotherapy cannot be fully understood without allowing for the phenomenon of resonance (mentioned earlier and discussed at greater length in chapter 10). Understanding resonance will perhaps one day explain how certain wavelengths of light can interact with various aspects of our internal energy field, as in the concept of the living matrix, discussed in the previous chapter.
Since chromotherapy is related to holistic concepts like consciousness and energy fields, notions that are still foreign to the present medical system, it is not surprising that it lies at the fringes of conventional medicine. Yet in truth no one can say for certain exactly how color affects us. As we mentioned at the beginning of this book, its influence is multidimensional; it acts simultaneously at the biophysical, energetic, and mental levels. So let’s take a closer look at how this occurs.
Color through the Visual System
The primary way that light, and thus color, influences us is through the visual system. In chapter 4 we looked at the two main optic pathways: the visual optic pathway (or retinocortical pathway) that gives us sight, and the nonvisual optic pathway that links the retina to the hypothalamus and synchronizes our internal clock. Beyond these two main pathways are other neuronal connections, the retinotectal pathway and the accessory optic tract, which issue from the optic nerve and show the extent to which light reaches into most of the brain’s centers. The four optical pathways stimulated by color are thus far-reaching, influencing every level of the cerebral processes: physiological, emotional, and cognitive, both conscious and unconscious.
As if this brief exploration of visual brain function is not already complex, I will add this last note: multiple feedback loops crisscross the various optic pathways, rendering the separate study of each one rather complicated, since they are interrelated. Ultimately, brain function is wonderfully unified. Indeed, Vanderwalle has described how, using functional magnetic resonance imaging (fMRI), he was able to see the effects of a blue light stimulus targeting the hypothalamus through the nonvisual optic pathway gradually diffuse to other zones until it reached the whole cerebral cortex—and this entire process took place in about twenty minutes.
The Four Chromatic Pathways of the Visual System:
Vision, the “royal road” of color: From the visual cortex where the visual optic pathway ends, the neuronal signals initiated by color are transmitted to a multitude of brain areas involved in cognition that are in the cortex, as well as in the regulation of emotions in the midbrain (see fig. 8.1). This optic pathway of color has a conscious as well as an unconscious influence. Color information from the visual pathway is thus brought all the way to the limbic system, where the amygdala controls our most instinctive emotional reactions. This opens the way for the psychotherapeutic use of chromotherapy as well as its use in treating physical ailments through psychosomatic processes.