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1.
IEEE Trans Neural Netw ; 22(12): 2032-49, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22049366

RESUMO

We introduce a wait-and-chase scheme that models the contact times between moving agents within a connectionist construct. The idea that elementary processors move within a network to get a proper position is borne out both by biological neurons in the brain morphogenesis and by agents within social networks. From the former, we take inspiration to devise a medium-term project for new artificial neural network training procedures where mobile neurons exchange data only when they are close to one another in a proper space (are in contact). From the latter, we accumulate mobility tracks experience. We focus on the preliminary step of characterizing the elapsed time between neuron contacts, which results from a spatial process fitting in the family of random processes with memory, where chasing neurons are stochastically driven by the goal of hitting target neurons. Thus, we add an unprecedented mobility model to the literature in the field, introducing a distribution law of the intercontact times that merges features of both negative exponential and Pareto distribution laws. We give a constructive description and implementation of our model, as well as a short analytical form whose parameters are suitably estimated in terms of confidence intervals from experimental data. Numerical experiments show the model and related inference tools to be sufficiently robust to cope with two main requisites for its exploitation in a neural network: the nonindependence of the observed intercontact times and the feasibility of the model inversion problem to infer suitable mobility parameters.


Assuntos
Encéfalo/fisiologia , Modelos Neurológicos , Morfogênese/fisiologia , Rede Nervosa/fisiologia , Reconhecimento Automatizado de Padrão/métodos , Animais , Simulação por Computador , Humanos , Movimento (Física) , Movimento
2.
Brain Res Rev ; 55(1): 108-18, 2007 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-17418422

RESUMO

We consider a homeostatic mechanism to maintain a plastic layer of a feed-forward neural network reactive to a long sequence of signals, with neither falling in a fixed point of the state space nor undergoing in overfitting. Homeostasis is achieved without asking the neural network to be able to pursue an offset through local feedbacks. Rather, each neuron evolves monotonically in the direction increasing its own parameter, while a global feedback emerges from volume transmission of a homostatic signal. Namely: 1) each neuron is triggered to increase its own parameter in order to exceed the mean value of all of the other neurons' parameters, and 2) a global feedback on the population emerges from the composition of the single neurons behavior paired with a reasonable rule through which surrounding neurons in the same layer are activated. We provide a formal description of the model that we implement in an ad hoc version of pi-calculus. Some numerical simulations will depict some typical behaviors that seem to show a plausible biological interpretation.


Assuntos
Lógica , Modelos Neurológicos , Neurônios/fisiologia , Transmissão Sináptica/fisiologia , Animais , Simulação por Computador , Humanos
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