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Anne Martin, Rudiger von der Heydt; Firing synchrony between neurons reveals proto-object representation in monkey visual cortex. Journal of Vision 2013;13(9):289. doi: https://doi.org/10.1167/13.9.289.
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An unresolved question in neuroscience is how the brain represents objects. Theories have proposed that synchrony of firing might encode how features relate to objects (feature binding theory[sup]1,2[/sup]), or highlight information for selective processing (attention coding theory[sup]3[/sup]), but the underlying mechanisms are largely unknown. One hypothesis is that synchrony in visual cortex is produced by shared feedback from ‘grouping cells’ that specifically enhance the activity of neurons whose receptive fields fit their grouping templates. This mechanism is thought to instantiate proto-objects, providing a structure for selective attention[sup]4,5[/sup]. Here we show that spike time correlations between neurons in monkey visual cortex (V1, V2) reveal the workings of this mechanism. We used border ownership selectivity[sup]6[/sup] to infer how neurons are linked in proto-object structures (POS). We found that synchrony depends on whether two neurons are part of the same POS. Synchrony was three times higher in same-POS pairs than in different-POS pairs. Synchrony in same-POS pairs increased when they were stimulated by contour segments of the same object (binding) compared to segments of different objects, whereas in other pairs it did not change. In same-POS pairs, synchrony decreased with attention, in the others it increased. These results confirm the existence of specific feedback circuits that define proto-objects. While previous theories have linked synchrony in visual cortex to stimulus configuration and mode of attention, our results show that the key to understanding synchrony is the place of the neurons in the proto-object representation. References: 1. von der Malsburg,C. In Brain Theory. Proceedings of the First Trieste Meeting on Brain Theory, 1984. 2. Gray,C.M., et al. Nature (1989). 3. Niebur,E., et al. Vision Res. (1993). 4. Craft,E., et al. J. Neurophysiol. (2007). 5. Mihalas,S., et al. PNAS (2011). 6. Zhou,H., et al. Journal of Neuroscience (2000).
Meeting abstract presented at VSS 2013
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