Context-enabled learning in the human visual system

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Training was found to improve the performance of humans on a variety of visual perceptual tasks1,2. However, the ability to detect small changes in the contrast of simple visual stimuli could not be improved by repetition3. Here we show that the performance of this basic task could be modified after the discrimination of the stimulus contrast was practised in the presence of similar laterally placed stimuli, suggesting a change in the local neuronal circuit involved in the task. On the basis of a combination of hebbian and anti-hebbian synaptic learning rules compatible with our results, we propose a mechanism of plasticity in the visual cortex that is enabled by a change in the context.

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Figure 1: Experimental conditions.
Figure 2: Changes in the contrast-discrimination curves.
Figure 3: The time course of the context-induced learning.
Figure 4: Putative synaptic mechanism and model simulations.


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We thank E. Ahissar, Y. Dudai and H. Markram for helpful comments on the manuscript. This research was supported by the Israeli Academy of Sciences, US-Israel Binational Foundation, the Office of Naval Research and the National Science Foundation.

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Correspondence to Dov Sagi.

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Adini, Y., Sagi, D. & Tsodyks, M. Context-enabled learning in the human visual system. Nature 415, 790–793 (2002) doi:10.1038/415790a

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