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Ke Jia, Xin Xue, Sheng Li; Motion discrimination learning improves perceptual representation and accelerates sensory evidence accumulation. Journal of Vision 2014;14(10):1161. doi: https://doi.org/10.1167/14.10.1161.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: By combining behavioral paradigm of perceptual learning (PL) and diffusion model (DM) of perceptual decision (PD), previous studies have found that PL can increase drift rate, a parameter that represents the rate of sensory evidence accumulation in PD process. Here we conducted an fMRI experiment to investigate the neural mechanism of such learning-related facilitation effect. Methods: We trained participants on a motion discrimination task for ten days. Before and after the training, participants' motion discrimination sensitivity was measured inside the scanner. Behavioral data were analyzed with linear ballistic accumulator model (LBA). LBA has the advantage over the traditional DM for its convenience in estimating the single trial parameters. Preprocessed fMRI data were decomposed with spatial group independent component analysis (ICA). Robust ICs were deconvolved to extract the single trial brain activity. The trial-to-trial co-fluctuation between the parameters of the LBA model and the fMRI activity was considered as the indicator for the involvement of a brain area in the representation of the model parameters. Results: (1) Behavioral results: Training significantly improved the motion direction discrimination sensitivity around the trained direction specifically. (2) Modelling results: The behavioral training effect could be attributed to the increased drift rate that was specific for the trained direction. (3) fMRI results: V3A and MT+ showed a specific decrease in fMRI signal to the trained direction. However, the learning-related trial-to-trial fluctuation of the drift rate correlated only with the activity of V3A. Conclusion: These results suggest that PL improves the perceptual representation of the motion stimulus along the trained direction. This improvement subsequently speeds up the process of sensory evidence accumulation in PD and may account for the observed behavioral learning effect. The neural signature of the transition from the improved perceptual representation to the accelerated PD process was observed in area V3A.
Meeting abstract presented at VSS 2014
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