The balance of excitatory and inhibitory neurotransmitters in a key brain region strongly predicts how well the brain's default mode network (DMN) communicates internally. In 20 healthy men, glutamate and GABA levels in the posteromedial cortex (a central DMN node) explained about half of the variation in the network's intrinsic functional connectivity. Glutamate correlated positively and GABA correlated negatively with DMN connectivity; the glutamate/GABA ratio also correlated positively. Age had no independent effect. No other brain network showed this relationship. The findings suggest that local neurotransmitter concentrations within a network hub can predict the functional integrity of that entire network.
The human brain's superior pattern processing (SPP) is the fundamental basis for unique features such as intelligence, language, imagination, invention, and belief in imaginary entities like ghosts and gods. SPP involves the electrochemical, neuronal network-based encoding, integration, and transfer of perceived or mentally-fabricated patterns. During evolution, pattern processing became more sophisticated with expansion of the cerebral cortex, especially the prefrontal cortex and image-processing regions. Patterns are reinforced by emotional experiences, indoctrination, and psychedelic drugs. Impaired SPP is fundamental to cognitive and psychiatric disorders. Understanding SPP mechanisms may enable interventions that reduce irrational decisions and destructive behaviors.