Neuroscientists have long recognized that the brain is an open, adaptive system and that the organism's experiences are environmentally contextualized. However, the proposition that sociocultural contexts may exert reciprocal influences on neurobiological mechanisms is rarely considered and could not be empirically explored until very recently. This chapter reviews an emerging trend of interdisciplinary research aimed at exploring the effects of sociocultural influences on human brain functioning. Viewed through the lens of a cross-level biocultural co-constructive framework, human development is co-constructed by biology and culture through a series of reciprocal interactions between developmental processes and plasticity at different levels. “Mental exercise facilitates a greater development of … the nervous collaterals in the part of the brain in use. In this way, preexisting connections between groups of cells could be reinforced …” (Ramón y Cajal, 1894, Croonian lecture to the Royal Society). Introduction: For more than a century, neuroscientists have been interested in how neural mechanisms implement mental experiences and how experiences may exert reciprocal influences on the neurobiological substrates of the mind. Ramón y Cajal enunciated what today is known as the “activity-dependent synaptic plasticity and memory hypothesis.” Since the formulation and discoveries of synaptic processes of memory and learning, a great variety of neurochemical mechanisms involved in tuning synaptic efficacy have been identified (see Bliss, Collingridge, & Morris, 2003, for a recent review).