Psychopathology of early frontal lobe damage: Dependence on cycles of development

Abstract

AbstractA new theory of frontal lobe development is presented in which the role of the human frontal lobes during normal development and the psychopathological consequences of early frontal lobe injury are explored. Analyses of the development of human electroencephalograph (EEG) coherence indicate that there are oscillations and cyclic growth processes along the mediolateral and anterior-posterior planes of the brain. The cycles of EEG coherence are interpreted as repetitive sequences of increasing and decreasing synaptic effectiveness that reflects a convergence process that narrows the disparity between structure and function by slowly sculpting and reshaping the brain's microanatomy. This process is modeled as a developmental spiral staircase in which brain structures are periodically revisited resulting in stepwise increases in differentiation and integration. The frontal lobes play a crucial role because they are largely responsible for the selection and pruning of synaptic contacts throughout the postnatal period. A mathematical model of cycles of synaptic effectiveness is presented in which the frontal lobes behave as gentle synaptic “predators” whereas posterior cortical regions behave as synaptic “prey” in a periodic reorganization process. The psychopathological consequences of early frontal lobe damage are discussed in the context of this model.