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Huihui Zhang, David Alais; Behavioral oscillations of criterion and sensitivity synchronized with action. Journal of Vision 2017;17(10):727. doi: 10.1167/17.10.727.
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© ARVO (1962-2015); The Authors (2016-present)
Voluntary action can synchronize ongoing brain oscillations, triggering rhythmical modulation of visual contrast sensitivity (Benedetto et al., 2016; Tomassini et al., 2015). In this study, we examined whether voluntary action could trigger oscillations of decision criterion as well as sensitivity, and how learning might affect these oscillations. Participants voluntarily pressed a button to start each trial. After variable time lags (0 - 800 ms, sampled every 5 ms), a brief noisy grating was presented at the fovea and participants discriminated its orientation (45° or -45°). A staircase was used to keep grating contrast at threshold level (75% correct response). Participants did two sessions on different days. Using signal detection theory, we calculated participants' sensitivity and criterion over time. To test the existence of oscillations, we fitted first-order Fourier series to the time series of sensitivity and criterion. We also performed Fast Fourier Transforms on these time series. With permutation tests we found alpha oscillations of both sensitivity (8.5 Hz) and criterion (10.5 Hz) that were synchronized with voluntary action. To reveal the influence of learning, we separately analysed the data from the first and second sessions. In the first session, sensitivity and criterion oscillated in the alpha range (10.2 Hz and 10.5 Hz, respectively). However, in the second session, we found no oscillations of criterion and the sensitivity oscillation reduced to 8.3 Hz. In summary, our results showed that action could synchronize oscillations of decision criterion as well as sensitivity, but oscillations of criterion only occurred at the early stage of learning. It may suggest different roles of alpha oscillations: alpha oscillations of sensitivity may reflect rhythmic attentional inhibition, whereas alpha oscillations of criterion may reflect the dynamic prestimulus perceptual expectations, which are susceptible to learning.
Meeting abstract presented at VSS 2017
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