Macroconnection ( Thompson & Swanson, 2010 ) : A connection between two gray matter regions; p. 15239. At this level of analysis gray matter regions are treated as black box nodes, disregarding their composition of neuron types (Bota & Swanson, 2007) and local connections. That is, macroconnections are described to and from particular gray matter regions, disregarding local connections within the gray matter regions. In normal, healthy animals global macroconnection patterns are genetically hardwired.

Mesoconnection ( Thompson & Swanson, 2010 ) : A connection between two neuron types (Bota & Swanson, 2007), or between a neuron type (Bota & Swanson, 2007) and another cell type like muscle or gland cells; p. 15239. At this level of analysis all axon connections from (outputs of) a particular neuron type (Bota & Swanson, 2007) are arranged in terms of a stereotyped collateralization (branching) pattern of the axon trunks of the neuron type (Bota & Swanson, 2007), with individual axon collaterals innervating specific neuron types (Bota & Swanson, 2007)-the individual axon connections of the neuron type. At this level of analysis mesoconnections are established by synapses (Foster & Sherrington, 1897). In normal, healthy animals global mesoconnection patterns are genetically hardwired.

Microconnection ( Thompson & Swanson, 2010 ) : A connection between two individual neurons (Waldeyer, 1891), or between one neuron and another cell like a muscle or gland cell; p. 15239. At this level of analysis connections are established by synapses (Foster & Sherrington, 1897). In normal, healthy animals qualitative aspects of microconnection patterns are genetically hardwired but their quantitative features can be modified by learning, stress, and a variety of other factors.