Part of Advances in Neural Information Processing Systems 6 (NIPS 1993)
Martin Stemmler, Marius Usher, Christof Koch, Zeev Olami
We investigate a model for neural activity that generates long range temporal correlations, 1/ f noise, and oscillations in global activity. The model consists of a two-dimensional sheet of leaky integrate(cid:173) and-fire neurons with feedback connectivity consisting of local ex(cid:173) citation and surround inhibition. Each neuron is independently driven by homogeneous external noise. Spontaneous symmetry breaking occurs, resulting in the formation of "hotspots" of activ(cid:173) ity in the network. These localized patterns of excitation appear as clusters that coalesce, disintegrate, or fluctuate in size while si(cid:173) multaneously moving in a random walk constrained by the interac(cid:173) tion with other clusters. The emergent cross-correlation functions have a dual structure, with a sharp peak around zero on top of a much broader hill . The power spectrum associated with single units shows a 1/ f decay for small frequencies and is flat at higher frequencies, while the power spectrum of the spiking activity aver(cid:173) aged over many cells-equivalent to the local field potential-shows no 1/ f decay but a prominent peak around 40 Hz.