Cortical organization in insectivora: The parallel evolution of the sensory periphery and the brain

Insectivores are traditionally described as a primitive group that has not changed much in the course of mammalian evolution. In contrast, recent stud ies reveal a great diversity of sensorimotor specializations among insectiv ores adapted to a number of different ecological niches, indicating that th ere has been significant diversification and change in the course of their evolution. Here the organization of sensory cortex is compared in the Afric an hedgehog (Atelerix albiventris), the masked shrew (Sorex cinereus), the eastern mole (Scalopus aquaticus), and the star-nosed mole (Condylura crist ata). Each of these four closely related species lives in a unique ecologic al niche, exhibits a different repertoire of behaviors, and has a different configuration of peripheral sensory receptors. Corresponding specializatio ns of cortical sensory areas reveal a number of ways in which the cortex ha s evolved in parallel with changes to the sensory periphery. These speciali zations include expansion of cortical representations (cortical magnificati on), the addition or loss of cortical areas in the processing network, and the subdivision of areas into modules (barrels and stripes). Copyright (C) 2000 S. Karger AG, Basel.