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

Optimization of the Transcranial Magnetic Stimulation Protocol by Defining a Reliable Estimate for Corticospinal Excitability

<div><p>The goal of this study was to optimize the transcranial magnetic stimulation (TMS) protocol for acquiring a reliable estimate of corticospinal excitability (CSE) using single-pulse TMS. Moreover, the minimal number of stimuli required to obtain a reliable estimate of CSE was investigated. In addition, the effect of two frequently used stimulation intensities [110% relative to the resting motor threshold (rMT) and 120% rMT] and gender was evaluated. Thirty-six healthy young subjects (18 males and 18 females) participated in a double-blind crossover procedure. They received 2 blocks of 40 consecutive TMS stimuli at either 110% rMT or 120% rMT in a randomized order. Based upon our data, we advise that at least 30 consecutive stimuli are required to obtain the most reliable estimate for CSE. Stimulation intensity and gender had no significant influence on CSE estimation. In addition, our results revealed that for subjects with a higher rMT, fewer consecutive stimuli were required to reach a stable estimate of CSE. The current findings can be used to optimize the design of similar TMS experiments.</p></div

Visual Analogue Scales (VAS).

<p>The mean VAS score ± standard deviation (SD) is shown for attention (0 = no attention; 10 = maximal attention), fatigue (0 = no fatigue; 10 = maximal fatigue) and arousal (0 = no arousal; 10 = maximal arousal). Measurements were obtained prior (PRE) and after (POST) the experiment. Data is shown for all subjects and for males and females separately. P-values in bold highlight a significant effect between PRE and POST measurement.</p

Probability table.

<p>The number of consecutive stimuli required as a function of the probability of hitting the 95% confidence interval (CI).</p

Data for subject 36 (a) and 34 (b) is illustrated.

<p>The Y-axis shows the MEP amplitude (mV), while the number of TMS stimuli (n) is shown on the X-axis. White dots represent the individual (raw) MEPs, whereas the black dots represent the average of consecutive MEPs (). Dashed lines represent the 95% confidence interval (CI), which is based upon all 40 stimuli. The upper panel (<b>a</b>) illustrates data that was included in the statistical analysis (slope estimate: 0.007; p = 0.355). For this particular subject, 8 consecutive stimuli were sufficient to enter the CI. The lower panel (<b>b</b>) shows data that has been excluded due to a significant change in slope over time (slope estimate: 0.062; p<0.001).</p

Results for gender (a) and intensity (b) based upon the raw data are illustrated.

<p>The Y-axis shows probability of inclusion in the 95% CI, while the number of TMS stimuli (n) is shown on the X-axis. The upper panel (<b>a</b>) illustrates the probability of inclusion in the 95% CI for females (white dots) and males rMT (black dots). The lower panel (<b>b</b>) illustrates the probability of inclusion in the 95% CI for the stimulation intensity of 110% rMT (white dots) and 120% rMT (black dots).</p

Generalized estimating equation (GEE) analysis.

<p>Estimates and p-values are shown for the number of consecutive stimuli, arousal, fatigue, resting motor threshold and the interaction between arousal and fatigue. P-values in bold highlight a significant effect.</p

The number of TMS stimuli required to reach a probability of 1.0 for hitting the 95% CI was estimated using the GEE analysis for different levels of resting motor threshold (rMT).

<p>The number of TMS stimuli required to reach a probability of 1.0 for hitting the 95% CI was estimated using the GEE analysis for different levels of resting motor threshold (rMT).</p

Age-related differences in corticospinal excitability during a choice reaction time task

Age-related declines in central processing may affect corticospinal (CS) excitability that underlies the emergence of voluntary responses to external stimuli. We used single-pulse transcranial magnetic stimulation (TMS) over the primary motor cortex to explore the evolution of CS excitability in 14 young and ten elderly healthy right-handed participants. Motor-evoked potentials (MEPs) were elicited in the right or left first dorsal interosseus (FDI) during the preparatory and premotor periods of a choice reaction time (CRT) task, which required selection of left or right index finger responses. Both age groups showed significant suppression of CS excitability in the preparatory period. However, suppression was generally less pronounced in older than in young adults. Moreover, our data indicated that a reduced suppression in the right FDI during the preparatory period was associated with longer reaction times (RTs) in older adults only. In the premotor period, both age groups demonstrated comparable facilitation levels towards movement onset. Our findings indicate that increased RTs among older individuals could be directly associated with declines in preparatory processes

Optimizing the Effect of tDCS on Motor Sequence Learning in the Elderly

One of the most visible effects of aging, even in healthy, normal aging, is a decline in motor performance. The range of strategies applicable to counteract this deterioration has increased. Transcranial direct current stimulation (tDCS), a non-invasive brain stimulation technique that can promote neuroplasticity, has recently gained attention. However, knowledge about optimized tDCS parameters in the elderly is limited. Therefore, in this study, we investigated the effect of different anodal tDCS intensities on motor sequence learning in the elderly. Over the course of four sessions, 25 healthy older adults (over 65 years old) completed the Serial Reaction Time Task (SRTT) while receiving 1, 2, or 3 mA of anodal or sham stimulation over the primary motor cortex (M1). Additionally, 24 h after stimulation, motor memory consolidation was assessed. The results confirmed that motor sequence learning in all tDCS conditions was maintained the following day. While increased anodal stimulation intensity over M1 showed longer lasting excitability enhancement in the elderly in a prior study, the combination of higher intensity stimulation with an implicit motor learning task showed no significant effect. Future research should focus on the reason behind this lack of effect and probe alternative stimulation protocols