GEOMETRIC AND FUNCTIONAL ANALYSIS OF MICROCIRCUIT DYNAMICS

Microcircuits, also known as local circuits, involve an excitatory recurrent feedback system,projection neurons,and inhibitory interneurons. Microcircuits are thought to serve as the morphological and functional units of brain function from sensation and locomotion to emotion and cognition. Is the architecture of microcircuits established deterministically or probabilistically? Is the functional activity of microcircuits correlated with the wiring design? To address these questions,stereology and neurogeometry seem to be promising tools for quantitative analysis of the morphometric parameters of microcircuits. Quantitation of specific synapses and synaptic connectivity is likely to provide a map of microcircuit wiring and even show a correlation between microcircuit architecture and functional dynamics. These methods and examples of microcircuits(cerebral cortex and nucleus of tractus solitarius)are introduced and discussed. (Tokyo Jikeikai Medical Journal 2009 ;124:63-70)