Developing velocity sensitivity in a model neuron by local synaptic plasticity.
Sensor neurons, like those in the visual cortex, display specific functional properties, e.g., tuning for the orientation, direction and velocity of a moving stimulus. It is still unclear how these properties arise from the processing of the inputs which converge at a given cell. Specifically, little is known how such properties can develop by ways of synaptic plasticity. In this study we investigate the hypothesis that velocity sensitivity can develop at a neuron from different types of synaptic plasticity at different dendritic sub-structures. Specifically we are implementing spike-timing dependent plasticity at one dendritic branch and conventional long-term potentiation at another branch, both driven by dendritic spikes triggered by moving inputs. In the first part of the study, we show how velocity sensitivity can arise from such a spatially localized difference in the plasticity. In the second part we show how this scenario is augmented by the interaction between dendritic spikes and back-propagating spikes also at different dendritic branches. Recent theoretical (Saudargiene et al. in Neural Comput 16:595-626, 2004) and experimental (Froemke et al. in Nature 434:221-225, 2005) results on spatially localized plasticity suggest that such processes may play a major role in determining how synapses will change depending on their site. The current study suggests that such mechanisms could be used to develop the functional specificities of a neuron.
Tamosiunaite
Minija
M
Department of Psychology, University of Stirling, Stirling, Scotland. m.tamosiunaite@if.vdu.lt
Porr
Bernd
B
Wörgötter
Florentin
F
D003712:Dendrites / Q000502:physiology; D006801:Humans; D007858:Learning / Q000502:physiology; D008959:Models, Neurological; D009473:Neuronal Plasticity / Q000502:physiology*; D009949:Orientation; D012680:Sensitivity and Specificity; D013569:Synapses / Q000502:physiology*; D014793:Visual Cortex / Q000502:physiology