Annual Report Town of Bowdoinham Maine 2013

Perceptual processes play an important role in motor learning. While it is evident that visual information greatly contributes to learning new movements, much less is known about provision of prescriptive proprioceptive information. Here, we investigated whether passive (proprioceptively-based) movement training was comparable to active training for learning a new bimanual task. Three groups practiced a bimanual coordination pattern with a 1∶2 frequency ratio and a 90° phase offset between both wrists with Lissajous feedback over the course of four days: 1) passive training; 2) active training; 3) no training (control). Retention findings revealed that passive as compared to active training resulted in equally successful acquisition of the frequency ratio but active training was more effective for acquisition of the new relative phasing between the limbs in the presence of augmented visual feedback. However, when this feedback was removed, performance of the new relative phase deteriorated in both groups whereas the frequency ratio was better preserved. The superiority of active over passive training in the presence of augmented feedback is hypothesized to result from active involvement in processes of error detection/correction and planning.status: publishe

Testing Multiple Coordination Constraints with a Novel Bimanual Visuomotor Task

The acquisition of a new bimanual skill depends on several motor coordination constraints. To date, coordination constraints have often been tested relatively independently of one another, particularly with respect to isofrequency and multifrequency rhythms. Here, we used a new paradigm to test the interaction of multiple coordination constraints. Coordination constraints that were tested included temporal complexity, directionality, muscle grouping, and hand dominance. Twenty-two healthy young adults performed a bimanual dial rotation task that required left and right hand coordination to track a moving target on a computer monitor. Two groups were compared, either with or without four days of practice with augmented visual feedback. Four directional patterns were tested such that both hands moved either rightward (clockwise), leftward (counterclockwise), inward or outward relative to each other. Seven frequency ratios (3∶1, 2∶1, 3∶2, 1∶1, 2∶3. 1∶2, 1∶3) between the left and right hand were introduced. As expected, isofrequency patterns (1∶1) were performed more successfully than multifrequency patterns (non 1∶1). In addition, performance was more accurate when participants were required to move faster with the dominant right hand (1∶3, 1∶2 and 2∶3) than with the non-dominant left hand (3∶1, 2∶1, 3∶2). Interestingly, performance deteriorated as the relative angular velocity between the two hands increased, regardless of whether the required frequency ratio was an integer or non-integer. This contrasted with previous finger tapping research where the integer ratios generally led to less error than the non-integer ratios. We suggest that this is due to the different movement topologies that are required of each paradigm. Overall, we found that this visuomotor task was useful for testing the interaction of multiple coordination constraints as well as the release from these constraints with practice in the presence of augmented visual feedback

Bimanual tracking task (BTT).

<p><i>(A) Task set-up</i>. Subjects were seated in front of a computer screen on which the task was displayed. The response apparatus consisted of two dials which were fixated on a ramp. Direct vision of the forearms was prevented by a horizontal table-top bench. <b><i>(B) Frequency ratios and coordination directions</i></b>. Schematic drawing of the target lines shown on the screen, from which subjects can deduct the three frequency ratios (1∶1, 2∶3 and 1∶2) and coordination directions [clockwise (CW) and counterclockwise (CCW)]. The coordination directions inwards (IN) and outwards (OUT) are shown here, but are not a part of the training protocol.</p

1∶1 frequency ratio.

<p>Error score (ATDlog, i.e. the log-transformed average target deviation) for baseline, acquisition phase (TR1-16), immediate retention (IR) and delayed retention (DR) (mean ± standard error) learned under either a blocked (black circles) or randomized (white squares) practice schedule. Better performance is indicated with lower levels of ATDlog.</p

Training schedule.

<p><i>(A) Training protocol</i>. Baseline performance was assessed without concurrent FB (NFB) on day 1 prior to training. The acquisition phase consisted of 3 training days within one week. Because of the fading feedback schedule, all 3 feedback conditions were present during each day of training. Immediate retention (IR) was conducted 5 min after the end of training day 3 and delayed retention (DR) was conducted 7 days later. Both IR and DR consisted of 2 types of retention schedule, i.e. a blocked (IR-B and DR-B) and a random (IR-R and DR-R) schedule. <b><i>(B) Blocked and randomized practice schedule</i></b>. Subjects in the blocked practice group were exposed to one frequency ratio in both clockwise (CW) (blocks 1–3) and counterclockwise (CCW) (blocks 4–6) directions per day. In contrast, subjects in the randomized practice group were exposed to all 6 trial types (which were randomly presented) during each block, i.e. 4 trials per trial type in each block during training. The number of different feedback (cFB, atFB and NFB) trials and the degree of fading feedback within each trial type was identical in both groups. Therefore, concurrent feedback (cFB) in the blocked practice group faded over blocks 1 to 3 after which the fading feedback schedule repeated itself during the next 3 blocks. In contrast, in the randomized practice group, fading feedback was distributed over days within each trial type.</p

2∶3 frequency ratio.

<p>Error score (ATDlog, i.e. the log-transformed average target deviation) for baseline, acquisition phase (TR1-16), immediate retention (IR) and delayed retention (DR) (mean ± standard error) learned under either a blocked (black circles) or randomized (white squares) practice schedule. Better performance is indicated with lower levels of ATDlog.</p

Three types of FB conditions.

<p>Concurrent visual feedback, provided by a red cursor indicative of subjects' current position, was only provided in the concurrent visual feedback (cFB) condition. In the after-trial feedback (atFB) condition, a motionless representation of the produced red line was provided after the execution phase while no feedback was provided during the execution phase. In the no feedback (NFB) condition, no concurrent or after-trial feedback was provided. Every trial started with a planning phase of 2 s where a yellow cue, which indicated whether cFB would be given in the upcoming trial, was presented. During the execution phase, the white target dot moved with constant speed along the blue target line for 9 s. In each condition, the inter-trial interval (ITI), i.e. the time between each trial where no movement was required, lasted 3 s. During ITI, atFB was provided for 1 s in the atFB condition. Instead, a black screen was presented in the cFB and NFB condition.</p

The attentional blink task.

<p><b>Example of a trial.</b></p

T1- and T2-object specific activity during the localizer task (A) and the AB task (B).

<p>A: Selective activity in the EBA and PPA during the localizer task to bodies and scenes, respectively. B: Activity in the EBA and PPA during the AB task as a function of conscious T2 perception (blink, no-blink). While the EBA was equally active in no-blink and blink trials, the PPA exhibited significantly greater activation when T2 was consciously perceived.</p

Brain regions associated with conscious T2 perception (A) and body parts and natural scenes (B).

<p>A: Frontoparietal network associated with conscious T2 perception (<i>p</i><0.05 after controlling for False Discovery Rate). LPFC, lateral prefrontal cortex; SMFC, superior medial frontal cortex; PCG, precentral gyrus; IPS, intraparietal sulcus; PPA, parahippocampal place area; STRI, striatum. B: Localizer task data. The ‘representative subject’ map shows the 8 most active contiguous voxels for each region of interest (p<.0001). The ‘group data’ map is thresholded at q<.05 (or p<.0006).</p