Biologically Plausible Models of Topographic Map Formation in the Somatosensory and Auditory Cortices

Computational models of the somatosensory and auditory systems have been constructed with the neurosimulator GENESIS. The somatosensory model consists of a cortical layer with 1024 pyramidal cells and 512 basket cells connected to a hand surface with 512 tactile receptors. The auditory model consists of a cortical layer with 2256 pyramidal cells and 1128 basket cells connected to a cochlea with 47 receptors. The models reproduce processes related to the formation and maintenance of somatotopic and tonotopic maps and exhibit several features observed in experiments with animals such as variability in the shapes and sizes of areas of cortical representation and, in the case of somatotopy, cortical magnification values in agreement with experimental findings and linear decay of receptive field overlap as a function of cortical distance between recording sites in normal conditions.