Connectivity Cognition and Psychosis in the Physical Brain (pp. 267-276)
Authors: Avi Peled
Abstract: The brain is composed of multiple levels of elements ranging from single neurons interconnected by axons dendrites and synapses, up to brain regions and neural network ensembles connected by multiple modalities, from direct physical pathways to synchronized functional connectivity. We know that the brain integrates information going from lower level unimodal processing to multimodal and transmodal higher levels and that higher levels effect lower levels creating a top-down bottom-up balance in the hierarchy. This process of local versus global integration is well supported by the small-world organization recently described for effective optimized neural networks.
Schizophrenia spectrum disorders can be reconceptualized as different combinations of connectivity and hierarchy imbalances involving disconnectivity, over-connectivity, bottom-up insufficiency and top-down shifts. The different clinical manifestations depend on which of these disturbances is predominant at the time of the examination of the patient.
The course of schizophrenia over time typically begins with a psychotic episode, progresses to post-psychotic residual manifestations, and over longer periods of time repeated psychotic episodes. Considering this course of the disease over-time, it seems that the disorder is triggered by a disconnection disturbance which the brain supposedly tries to correct, probably by over-connecting the system, plunging it to over-connectivity dynamics with deficient negative symptoms. In an attempt to re-optimize the hierarchy, the system disconnects again achieving a consecutive psychotic episode, thereafter becoming even-more over-connected and deficient, thus the disease progresses with the brain oscillating between connectivity imbalances each time destroying more and more of the hierarchy of brain organization.