Proposição de rede neuronal fisiologicamente plausível para o estudo da dinâmica dos sistemas cerebrais (original) (raw)
The processing of information by the brain is a major scientific challenge of our time. It is a complex question that requires advances at various levels of expertise. In one of these levels, the systemic neuroscience, it is studied the behavior of systems of neurons. Two of the main difficulties in this study are the design of network topology and the selection of physiological properties which influence its dynamics. Both compose the objective of this work. It is proposed a "Physiologically Plausible Neuronal Network", PPNN, in which the network structure and its dynamics reproduce a range of physiological data considered significant. The network is applied to the primary visual system of macaque monkey, via object recognition. The structure of the network plays the complexity of the connections between the V1 layers and takes into account the spatial position of each one of the synapses. The sizes of dendritic and axonal trees, and the speed of the signal on each of them, are used for the time discretization in the computational program. Among the properties that influence their dynamics are the excitatory post-synaptic potential, the space constant in the dendritic membrane, and the refractory period. The computational structure is built in way of to attend the limits of memory and processing capability of the available computers. The stimuli applied in the retina are reflected in the primary visual system in the form of avalanches and waves of activity. The patterns of response are similar to those obtained experimentally with systems of excitatory neurons and show that the network operates in the critical region. v _________________________________________________________________________ Notação _________________________________________________________________________ c m Capacitância por unidade de comprimento do axônio EPSP Potencial pós-sináptico excitatório f Freqüência da onda i m Corrente iônica IPSP Potencial pós-sináptico inibitório M Magnocelular NGL Núcleo geniculado lateral P Parvocelular PA Potencial de ação PR Período refratário PSP Potencial pós-sináptico r a Resistência longitudinal r i Resistência interna r m Resistência da membrana RNFP Rede neuronal fisiologicamente plausível T Período da onda TI Córtex temporal inferior TM Córtex temporal médio V m Potencial de membrana V 0 Potencial de membrana na posição inicial do estímulo V1 Córtex visual primário V2 Córtex visual secundário V3 e V4 Áreas visuais terciárias y m Amplitude da onda
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