the properties of chemical compounds, the spectrum of sunlight;others are probabilistic). Natural selection not only selects genes, but also includes or excludes (selects) environmental factors as part of this inheritance by selecting for genes that specify developmental programs that either involve various factors in development or render them irrelevant. We hypothesize that what is genetically specified should be a first order set of developmental programs (distributed in the gross structure of the early brain): programs that bootstrap their way uphill to greater levels of functional organization through programmed endogenous interactions, and interactions with evolutionarily targetted environmental invariants that supply missing information. Because the functions of the brain's network of neural devices are computational rather than physical or chemical, the developmental programs in the brain must necessarily use evolved computational criteria?adaptive targets?to guide the process of wiring to the final levels of functional precision. That is, each functionally distinct evolved neural unit must contain feedback-driven developmental programs that test the unit (including expected inputs and computed outputs) against its own proprietary set of computational benchmarks (adaptive targets). This system can detect the degree to which its computations conform to its required functional specifications, and use this error term as input to feedback-driven adjustments until the target coordination is achieved. Robustly specified adaptive targets allow the developing brain to anti- entropically countervail against environmental perturbations, genetic noise (except in the specification of the adaptive targets), and insults, so that the necessary evolved computational interrelationships are exactingly achieved, even though substantial individual differences in the physical layout may emerge in the course of wiring around an insult. On this view, observed neural plasticity is not a mechanism, but an effect of a diverse set of adaptively highly targeted, hill-climbing mechanisms. The intuitively appealing idea of global ?plasticity?or general flexibility is an insufficient way of describing the principles involved because flexibility just means the capacity to vary, and there are vastly more potential variants that are wrong than are functional. The hard computational problem for developmental programs is the identification, out of the vast space of possible configurations, of that tiny subset that create, improve or restore function. Heterogeneous sets of adaptive targets are the necessary solution required to build the species'diverse complement of neurocognitive mechanisms, because each must compute different functional outputs according to their own divergent proprietary evolved criteria of functional
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