The Journal of Neuroscience, May 31, 2006, ():
Saccadic Suppression of Retinotopically Localized Blood Oxygen Level-Dependent Responses in Human Primary Visual Area V1
J. Neurosci. Vallines and Greenlee
26: 5965
Supplemental data
Files in this Data Supplement:
- supplemental material
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SD. 1 Can V1 responses 8ms Gabor stimuli be measured with fMRI? After retinotopically localizing the Gabors, three fMRI sessions were conducted to confirm the detectability of such short-lived responses in V1 (blue). During these sessions, Gabors were repeatedly presented for 8 ms every 9 s (plus a random jitter) while maintaining fixation. In this event related peristimulus-time histogram (obtained from averaging time-series extracted from the four regions of interest) we can appreciate how BOLD signal significantly increases when the Gabors were presented (p < 0.000001).
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SD. 2 Psychometric function for the orientation discrimination task were obtained for each subject by using a standard constant stimulus procedure with rotation values of 1, 2, 3, 6, 12, 24 and 48 degrees. Rotation values yielding correct responses in 80% of the trials were used in the main experiment to avoid floor and ceiling effects.
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SD. 3 Presentation delays. To account for presentation delays, we recorded the digital page-change triggers coming from the stimulus generator (red) together with the actual Projector’s luminance output (green) measured on the screen. Image formation started systematically one frame after actual analog-signal output of the VSG. Discounting rise and decay times (FWHM), we estimated an effective onset stimulus duration of 8 ms (blue). These values were used to precisely calculate SOAs and make sure stimuli included in the analysis were presented before the onset of the saccade.
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SD. 4 Saccadic onset detection. Saccadic onset detection accuracy was visually inspected by plotting the eye traces from the detected onset to make sure that in all analyzed trials, the Gabor stimuli where presented presaccadically. On this plot, the detection accuracy for one session is presented.
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SD. 5 BOLD response magnitude for the ROI as a function of peristimulus time, where zero corresponds to the event onset. The curves depict fitted HRFs to BOLD measurements from the Gabors-only condition (G, circles), the saccade-only condition (S, squares) and the Gabor-plus-saccade condition (G+S, triangles, discarded trials from one session). The amplitude of responses in the G+S condition roughly corresponds to the summation of the effects from the S and the G control conditions. Each data point depicts the average BOLD response for all voxels within the ROI
