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quarta-feira, julho 15, 2009

Oscilações e ruído nos dendritos?


Preciso dar uma olhada nessas tais oscilações dendríticas.


No modelo de Gollo et al., imagino que se houverem loops, seria possível a criação de ondas recorrentes auto-sustentadas, que seriam identificadas com oscilações periódicas. Seria isso?



Michiel Remme1, Mate Lengyel2, & Boris Gutkin1
Correspondence: (Login to view email address)
Group for Neural Theory, LNC, INSERM U960, Department of Cognitive Studies, Ecole Normale Superieure
Computational and Biological Learning Lab, Department of Engineering, University of Cambridge, Cambridge, United Kingdom


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Received 11 June 2009 15:59 UTC; Posted 12 June 2009

Abstract:
The dendritic tree contributes significantly to the elementary computations a neuron performs while converting its synaptic inputs into action potential output. Traditionally, these computations have been characterized as temporally local, near-instantaneous mappings from the current input of the cell to its current output, brought about by somatic summation of dendritic contributions that are generated in spatially localized functional compartments. However, recent evidence about the presence of oscillations in dendrites suggests a qualitatively different mode of operation: the instantaneous phase of such oscillations can depend on a long history of inputs, and under appropriate conditions, even dendritic oscillators that are remote may interact through synchronization. Here, we develop a mathematical framework to analyze the interactions of local dendritic oscillations, and the way these interactions influence single cell computations. Combining weakly coupled oscillator methods with cable theoretic arguments, we derive phase-locking states for multiple oscillating dendritic compartments. We characterize how the phase-locking properties depend on key parameters of the oscillating dendrite: the electrotonic properties of the (active) dendritic segment, and the intrinsic properties of the dendritic oscillators. As a direct consequence, we show how input to the dendrites can modulate phase-locking behavior and hence global dendritic coherence. In turn, dendritic coherence is able to gate the integration and propagation of synaptic signals to the soma, ultimately leading to an effective control of somatic spike generation. Our results suggest that dendritic oscillations enable the dendritic tree to operate on more global temporal and spatial scales than previously thought.

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