Abstract
Training on a visual task leads to increased perceptual and neural responses to visual features that were attended during training as well as decreased responses to neglected distractor features. However, the time course of these attention-based modulations of neural sensitivity for visual features has not been investigated before. Here we measured event related potentials (ERP) in response to motion stimuli with different coherence levels before and after training on a speed discrimination task requiring object-based attentional selection of one of the two competing motion stimuli. We found that two peaks on the ERP waveform were modulated by the strength of the coherent motion signal; the response amplitude associated with motion directions that were neglected during training was smaller than the response amplitude associated with motion directions that were attended during training. The first peak of motion coherence-dependent modulation of the ERP responses was at 300 ms after stimulus onset and it was most pronounced over the occipitotemporal cortex. The second peak was around 500 ms and was focused over the parietal cortex. A control experiment suggests that the earlier motion coherence-related response modulation reflects the extraction of the coherent motion signal whereas the later peak might index accumulation and readout of motion signals by parietal decision mechanisms. These findings suggest that attention-based learning affects neural responses both at the sensory and decision processing stages.
Highlights
Training on a visual perceptual task can induce long-lasting improvements in our ability to detect, discriminate or identify visual stimuli
We found that two peaks on the event related potentials (ERP) waveform were modulated by the strength of the coherent motion signal; the response amplitude associated with motion directions that were neglected during training was smaller than the response amplitude associated with motion directions that were attended during training.The first peak of motion coherence-dependent modulation of the ERP responses was at 300 ms after stimulus onset and it was most pronounced over the occipitotemporal cortex
Our ERP results revealed that training on a task which requires object-based attentional selection of one of the two competing, spatially superimposed motion stimuli will lead to strong modulation of the neural responses to these motion directions when measured in a training-unrelated motion direction discrimination task
Summary
Training on a visual perceptual task can induce long-lasting improvements in our ability to detect, discriminate or identify visual stimuli (for review see Fahle and Poggio, 2002; Fine and Jacobs, 2002). Motion directions that were attended during training evoke stronger fMRI responses in early visual cortical areas, including the motion-sensitive human area MT+, than directions that were neglected during training (Gál et al, 2009). These results show that object-based attentional selection during training guides learning processes that will affect overall perceptual sensitivity and neural responses both to the task-relevant and the task-irrelevant visual features present during training. The main goal of the current study was to test whether attention-based learning influences perceptual sensitivity for the visual features present during training via modulating the sensory gain for the different features at the early stages of visual cortical processing and/or by biasing the decision processes at the higher processing stages
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