A schematic representation of a single trial demonstrating a counter-clockwise change in motion axis about a bisecting motion axis of 45°.

<p>The bisecting axis is depicted with solid grey lines (not present in the real stimuli). The lower panel illustrates the two possible relative phases of dot motion. Counter-phase dots provided locally balanced motion directions and therefore putatively suppressed MT. In-phase dots did not have locally balanced motion signals and therefore MT was presumed to be activated normally. Arrows are shown for illustrative purposes only.</p

An outline of the experimental design<b>.</b>

<p>The main experiment employed protocol 1 whereby learning related changes in the response of hMT+ and V1 were compared between two groups, one trained on in-phase dots and the other trained on counter-phase dots. Protocol 2 applied only to the group trained on counter-phase dots and compared the response of hMT+ and V1 to in-phase vs. counter-phase dots pre and post training (within subjects). A total of 11 participants were trained on counter-phase dots and 6 completed both scanning protocols after training. Same angle refers to the angular difference in motion axis orientation that gave rise to 75% correct before training. Smaller angle refers to the angular difference corresponding to 75% correct after training.</p

The effect of counter-phase dot training on the response of hMT+ and V1 to counter-phase and in-phase dot stimuli.

<p>Filled bars indicate counter-phase dots and open bars in-phase dots. Training increased the difference between in-phase and counter-phase dot responses at hMT+ for the trained motion axis.</p

Improvement in behavioural thresholds as a result of learning for participants trained on in-phase dots (A) and counter-phase dots (B).

<p>Each training session consisted of 400 trials. If 75% correct or better was achieved during a training session, the angular deviation was decreased by 1° for the subsequent training session. For two participants trained on counter-phase dots, the angular deviation was increased for two sessions mid-training in an attempt to facilitate additional learning. Each line represents an individual participant.</p

The relationship between the change in BOLD response and the amount of learning.

<p>The percent reduction in BOLD response pre to post training for the trained motion axis is shown on the Y axis and the percent improvement in 75% correct threshold a result of learning is shown on the X axis. Each data point represents an individual participant. Data are shown for hMT+ (top row) and V1 (bottom row) for counter-phase dots (left column) and in-phase dots (right column). Post training data are collapsed across angle size (“same and “smaller” angles).</p

The response of hMT+ and V1 to counter-phase vs. in-phase dot stimuli before training (n = 13).

<p>Data for individual participants are shown in panel A for hMT+ and panel B for V1. Data points lying above the unity line indicate a greater response to in-phase dots, consistent with motion opponency. Group averages are shown in panel C. * indicates a statistically significant difference (p&lt;0.01).</p

Localization of hMT+.

<p>The hMT+ localization stimulus is shown in panel A with yellow arrows representing the centripetal oscillations that occurred during the dynamic phase. Example localization results for one participant are shown in panel B. hMT+ localization data were acquired pre (top row) and post (middle row) training. The hMT+ ROI used for analysis was derived from the intersection of the pre and post training ROIs (bottom row). The FDR corrected (q&lt;0.001) statistical maps are rendered on inflated representations of the participant’s left and right cerebral hemispheres.</p

The response of hMT+ (%BOLD change) pre and post training with counter-phase dots (filled bars) or in-phase dots (open/textured bars).

<p>* indicates a significant reduction in the activation of hMT+ for the counter-phase dot stimulus presented along the trained motion-axis. Post training data are collapsed across angle size (“same” and “smaller” angles) as there were no differences in the BOLD response for this variable.</p

The response of V1 (%BOLD change) pre and post training with counter-phase dots (filled bars) or in-phase dots (open/textured bars).

<p>There were no reliable training-related changes in activation. Post training data are collapsed across angle size (“same” and “smaller” angles) as there were no differences in the BOLD response for this variable.</p

Behavioral results: Experiments 1 and 2.

<p>Behavioral accuracies averaged across 14 participants in 3°, 9°, and 15° conditions for the blocked (A) and event-related (B) designs in Experiment 1; and across 10 participants in 3°, 9°, 15°, and 80° conditions for the blocked (C) and event-related (D) designs in Experiment 2. Error bars denote 1 SEM of the mean here and in all subsequent figures.</p