The nuclear symptoms of schizophrenia reveal the four quadrant structure of language and its deictic frame

The "torque" constitutes a bias across the antero-posterior axis such that clorsolateral prefrontal cortex (DLPFC) on the right is thinner and wider than that on the left side, and occipito-parieto-temporal cortex (OPTC) is thinner and wider on the left than the right. Thus the human brain is distinguished from that of all other mammals by having 4 quadrants of association cortex - left and right motor, and right and left sensory. This has the consequences that i) each primary sensory or motor engram has an alternate form such that the pair conforms with De Saussure's separation of the signifieds from the signifiers, and ii) conceptual-intentional compartments, associated with "meaning" and "thought" respectively, are separated in the non-dominant hemisphere from articulatory-perceptual compartments in the dominant hemisphere. The nuclear symptoms of schizophrenia tell us what happens when the distinction between compartments (the deictic frame) breaks down. Thought, the precursor of speech, loses its characteristic autonomy-thoughts are inserted into, or removed from, the individual's mind. Conversely auditory hallucinations, such as thoughts spoken aloud, represent self-generated neural activity that activates phonological engrams normally only activated by speech from another individual. Thus schizophrenic symptoms are the key to the evolution of language. The genetic change (the 'speciation event') that created the torque and thereby the language circuit, carried with it disadvantageous variation that demarcates the scope and limits of normal function. (C) 2009 Elsevier Ltd. All rights reserved.