A Theory of Sulcal-Gap Signalization

Abstract

Two sulcal-gap signalization systems are hypothesized to have evolved as emergent functional “exaptations” having the capacity to transmit two-way cortex-to-cortex signals across tissues embedded in opposing sulcal banks. Hypothesis 1 posits that a primary sulcal-gap signalization system evolved the capacity to transmit nonlanguage signals within hierarchically lower-order sensory, motor, and perceptual functional areas of the neocortex having elemental functional units consisting of columns of about 110 neurons. Hypothesis 2 posits that a secondary sulcal-gap signalization system evolved the capacity to transmit language signals within hierarchically higher-order cognitive functional areas of the “neo-neocortex” having elemental functional units consisting of modules of about 4,000 neurons. Neuroanatomical, neurophysiological, neuroevolutionary, and neurodevelopmental evidence is presented in support of these two sulcal-gap hypotheses. It is speculated that the combined cognitive capacities of these two sulcal-gap signalization systems may contribute to the transduction of physiological brain into psychological mind.