Functional roles of three cues that provide nonsynaptic modes of communication in the brain: electromagnetic field, oxygen, and carbon dioxide.

The integrative actions of the brain depend on the exchange of information among its computational elements. Hence, this phenomenon plays the key role in driving the complex dynamics of the central nervous system, in which true computations interact with noncomputational dynamical processes to generate brain representations of the body and of the body in the external world, and hence the finalistic behavior of the organism. In this context, it should be pointed out that, besides the intercellular interactions mediated by classical electrochemical signals, other types of interactions, namely, "cues" and "coercions," also appear to be exploited by the system to achieve its function. The present review focuses mainly on cues present in the environment and on those produced by cells of the body, which "pervade" the brain and contribute to its dynamics. These cues can also be metabolic substrates, and, in most cases, they are of fundamental importance to brain function and the survival of the entire organism. Three of these highly pervasive cues will be analyzed in greater detail, namely, oxygen, carbon dioxide, and electromagnetic fields (EMF). Special emphasis will be placed on EMF, since several authors have suggested that these highly pervasive energy fluctuations may play an important role in the global integrative actions of the brain; hence, EMF signaling may transcend classical connectionist models of brain function. Thus the new concept of "broadcasted neuroconnectomics" has been introduced, which transcends the current connectomics view of the brain.