Feedback contribution to surface motion perception in the human early visual cortex
- Department of Cognitive Neuroscience, Maastricht Brain Imaging Centre (MBIC) Faculty of Psychology and Neuroscience, Maastricht University, Netherlands
- Maastricht Center of Systems Biology (MACSBIO), Faculty of Science & Engineering, Maastricht University, Netherlands
- Center for Neuroscience Imaging Research, Institute for Basic Science and Department of Biomedical Engineering, N Center, Sungkyunkwan University, Republic of Korea
- Techna Institute and Koerner Scientist in MR Imaging, University Health Network, Canada
Figures
Figure 1 with 2 supplements
Stimulus Design.
(A) A ‘Pac-Man’ figure rotating about its centre served as the main experimental stimulus. This experimental condition is referred to as ‘motion induction stimulus’. (B) In the first of two control …
Figure 1—figure supplement 1
High-resolution image of the ‘Pac-Man’ stimulus and the texture background.
When this figure is rendered such that the radius of the disk is 3.75 cm, and viewed from a distance of approximately 57 cm, it gives an impression of what the stimuli looked like to the …
Figure 1—figure supplement 2
Experimental design.
Stimuli were presented in a block design with rest blocks of variable duration. The three stimulus conditions were presented in separate runs (A, B, C). A central fixation dot and the random texture …
Figure 2 with 1 supplement
Surface activation maps.
(A) Activation map for motion induction condition (stimulus shown in (B)), projected on the inflated cortical surface, for a representative subject (GLM parameter estimates for sustained response). A…
Figure 2—figure supplement 1
The Pac-Man stimulus caused positive and negative fMRI signal changes across visual cortex.
Shown are the z-scores for the GLM contrast Pac-Man dynamic (sustained response) against rest, overlaid on a brain-masked T1 image, for a representative subject. Negative signal changes are …
Figure 3
Projection of GLM parameters into visual space.
The parameter estimates for the three stimulus conditions (motion induction stimulus (A, D, G), static control stimulus (B, E, H), and dynamic control stimulus (C, F, I)) were projected into a model …
Figure 4 with 3 supplements
Cortical depth profiles of the apparent motion effect for the cortical representation of the stimulus centre (see Figure 2C & D).
Figure 4—figure supplement 1
Cortical depth profiles of all three condition contrasts, with (A, B, C) and without (D, E, F) spatial deconvolution for removal of signal spread due to draining veins.
There are three possible condition contrasts: motion induction vs. static control (blue line), motion induction vs. dynamic control (magenta line), and static control vs. dynamic control (yellow …
Figure 4—figure supplement 2
Cortical depth profiles of the apparent motion effect for the cortical representation of the stimulus edge (see Figure 2C and F).
Figure 4—figure supplement 3
Cortical depth profiles of the apparent motion effect for the cortical representation of the stimulus centre.
Same as Figure 4 in the main text, but showing single-subject profiles (light grey) in addition to group level profiles. Please note that the group level profiles are a weighted average, reflecting …
Figure 5 with 5 supplements
Response onset times in V1.
(A) Event-related fMRI timecourses for regions of interest corresponding to the stimulus centre (blue line) and the edge of the stimulus (orange line). The dotted vertical lines indicate the …
Figure 5—figure supplement 1
Event-related fMRI timecourses for region of interest corresponding to the stimulus centre (A, B, C) and the edge of the stimulus (D, E, F) in the right hemisphere.
The horizontal grey bar marks the duration of the stimulus block. All three stimulus conditions (represented by separate lines) evoked a sustained negative response in V1, V2, and V3 in cortex that …
Figure 5—figure supplement 2
Single-subject response onset times in V1.
Event-related fMRI timecourses for regions of interest corresponding to the stimulus centre (blue line) and the edge of the stimulus (orange line). Same as Figure 5, but with single-subject …
Figure 5—figure supplement 3
Event-related fMRI timecourses from an additional run with longer stimulus blocks, for V1 in the right hemisphere.
In order to further investigate the temporal dynamics of the stimulus-evoked response, we acquired and additional run during which the motion induction stimulus was presented with longer block …
Figure 5—figure supplement 4
Cortical depth profiles of the apparent motion effect for the cortical representation of the stimulus centre.
Similar to Figure 4, but separately for the early and late phases of the response. (A, B, C) The early response includes the second and third fMRI volumes after stimulus onset (i.e. ~2 to~6 s after …
Figure 5—figure supplement 5
Simulation of negative fMRI response at the cortical representation of the stimulus centre.
Figure 6
Event-related time courses from control experiment with texture background and uniform background, separately for regions of interest corresponding to the retinotopic representation of the centre of the stimulus (A) and to its edges (B).
Irrespective of the shape of the stimulus (square or ‘Pac-Man’), there is a positive response to the centre of the stimulus when the background is uniform (A, red and orange lines), and a negative …
Figure 7 with 3 supplements
Visual field projections of GLM parameter estimates from control experiment with texture background and uniform background, for V1.
A ‘Pac-Man’ figure and a square were presented either on a uniform background (A and C) or on a random texture background (B and D). When presented on a uniform background, the stimuli caused a …
Figure 7—figure supplement 1
Control experiment to investigate the response to the texture pattern, in the absence of any additional stimulus.
(A) A full-screen texture (same as the background in the main experiment; see Figure 1 and Figure 1—figure supplement 1 and Figure 1—figure supplement 2) was presented in a block design. The rest …
Figure 7—figure supplement 2
Additional control experiment, investigating the effect of a texture background on stimulus-induced responses relative to a uniform baseline (n = 1).
The grey bar underneath the signal timecourses indicates the duration of the stimulus. Time is given in volumes; the duration of one volume was 2.604 s.
Figure 7—figure supplement 3
Stimulus design of the control experiment.
The purpose of the control experiment was to investigate the role of the background and the stimulus shape. Participants were presented with a static ‘Pac-Man’ stimulus (same as in the main …
Figure 8
Schematic illustration of two possible interpretations of the present results.
(A) Higher cortical areas may integrate the global motion percept across hemispheres, and send feedback projections to superficial layers of V1. Subsequently, this re-entrant feedback would be sent …
Tables
Table 1
Comparison of stimulus parameters in Akin et al., 2014 and in the present study.
| Akin et al., 2014 | Present study | |
|---|---|---|
| Diameter of stimulus | 15° visual angle | 7.5° visual angle |
| Viewing mode | Central fixation task & passive viewing | Central fixation task |
| Rest block duration | 12 s | 18.7 s, 20.8 s, or 22.9 s |
| Stimulus block duration | 12 s | 10.4 s |
| Stimulus luminance | 503 cd/m2 | 163 cd/m2 |
| Mean background luminance | 189 cd/m2 | 8 cd/m2 |
| Oscillation rate of stimulus | 1.04 Hz | 0.85 Hz |
