Frank F. Zhu

Neural co-activation as a yardstick of implicit motor learning and the propensity for conscious control of movement.

Two studies examined EEG co-activation (coherence) between the verbal-analytical (T3) and motor planning (Fz) regions during a golf putting task. In Study 1, participants with a strong propensity to consciously monitor and control their movements, determined psychometrically by high scores on a movement specific Reinvestment Scale, displayed more alpha2 T3-Fz co-activation than participants with a weak propensity. In Study 2, participants who practiced a golf putting task implicitly (via an errorless learning protocol) displayed less alpha2 T3-Fz co-activation than those who practiced explicitly (by errorful learning). In addition, explicit but not implicit motor learners displayed more T3-Fz co-activation during golf putting under pressure, implying that verbal-analytical processing of putting movements increased under pressure. These findings provide neuropsychological evidence that supports claims that implicit motor learning can be used to limit movement specific reinvestment.

EEG activity during the verbal-cognitive stage of motor skill acquisition

This study examined changes in EEG activity associated with motor performance during the verbal-cognitive stage of skill learning. Participants (n=14) were required to practice a sequential finger tapping task. EEG activity was recorded both before and after short-term practice, during finger tapping and during two control conditions. EEG power (Fz, Cz, Pz, T3, T4) and coherence (T3-Fz, T4-Fz, Fz-Cz, Fz-Pz) were computed for the theta (4-8 Hz), slow alpha (8-10 Hz), fast alpha (10-12 Hz), slow beta (12-20 Hz), and fast beta (20-28 Hz) bandwidths. Changes in motor performance were rapid during the very early stages of practice and then slowed in accord with the law of practice. These changes were accompanied by increases of theta power at Fz and beta coherence at T4-Fz, suggesting that progression through the verbal-cognitive stage of a sequential finger tapping task is accompanied by more narrowed attention and improved mapping between the stimuli and the finger movements.

Cathodal Transcranial Direct Current Stimulation Over Left Dorsolateral Prefrontal Cortex Area Promotes Implicit Motor Learning in a Golf Putting Task.

BACKGROUND Implicit motor learning is characterized by low dependence on working memory and stable performance despite stress, fatigue, or multi-tasking. However, current paradigms for implicit motor learning are based on behavioral interventions that are often task-specific and limited when applied in practice. OBJECTIVE To investigate whether cathodal transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex (DLPFC) area during motor learning suppressed working memory activity and reduced explicit verbal-analytical involvement in movement control, thereby promoting implicit motor learning. METHODS Twenty-seven healthy individuals practiced a golf putting task during a Training Phase while receiving either real cathodal tDCS stimulation over the left DLPFC area or sham stimulation. Their performance was assessed during a Test phase on another day. Verbal working memory capacity was assessed before and after the Training Phase, and before the Test Phase. RESULTS Compared to sham stimulation, real stimulation suppressed verbal working memory activity after the Training Phase, but enhanced golf putting performance during the Training Phase and the Test Phase, especially when participants were required to multi-task. CONCLUSION Cathodal tDCS over the left DLPFC may foster implicit motor learning and performance in complex real-life motor tasks that occur during sports, surgery or motor rehabilitation.

Target-directed visual attention is a prerequisite for action-specific perception

Witt et al. (2008) have recently shown that golfers who putt with more success perceive the hole to be bigger than golfers who putt with less success. In three experiments, we systematically examined whether this phenomenon, labelled action-specific perception, depends on directing visual attention towards the action target. In Experiment 1 we replicated previously reported action-specific effects on perception in golf putting. In Experiments 2 and 3 we directly assessed whether action-specific effects on perception in golf putting are dependent on focusing visual attention on the target. To this end, the participants performed the putting task while visual attention towards the target was either completely withheld (Experiment 2) or divided over the target and other task-relevant objects (Experiment 3). No action-specific effects were found when visual attention towards the action target was occluded or partially diverted from the target. Together, our results provide evidence to suggest that focusing visual attention on the target while performing the action is a prerequisite for the emergence of action-specific perception.

Refining the Continuous Tracking Paradigm to Investigate Implicit Motor Learning

In two experiments we investigated factors that undermine conclusions about implicit motor learning in the continuous tracking paradigm. In Experiment 1, we constructed a practice phase in which all three segments of the waveform pattern were random, in order to examine whether tracking performance decreased as a consequence of time spent on task. Tracking error was lower in the first segment than in the middle segment and lower in the middle segment than in the final segment, indicating that tracking performance decreased as a function of increasing time-on-task. In Experiment 2, the waveform pattern presented in the middle segment was identical in each trial of practice. In a retention test, tracking performance on the repeated segment was superior to tracking performance on the random segments of the waveform. Furthermore, substitution of the repeated pattern with a random pattern (in a transfer test) resulted in a significantly increased tracking error. These findings imply that characteristics of the repeated pattern were learned. Crucially, tests of pattern recognition implied that participants were not explicitly aware of the presence of a recurring segment of waveform. Recommendations for refining the continuous tracking paradigm for implicit learning research are proposed.

Exploring Personality Dimensions That Influence Practice and Performance of a Simulated Laparoscopic Task in the Objective Structured Clinical Examination

BACKGROUND Surgical educators have encouraged the investigation of individual differences in aptitude and personality in surgical performance. An individual personality difference that has been shown to influence laparoscopic performance under time pressure is movement specific reinvestment. Movement specific reinvestment has 2 dimensions, movement self-consciousness (MS-C) (i.e., the propensity to consciously monitor movements) and conscious motor processing (CMP) (i.e., the propensity to consciously control movements), which have been shown to differentially influence laparoscopic performance in practice but have yet to be investigated in the context of psychological stress (e.g., the objective structured clinical examination [OSCE]). OBJECTIVE This study investigated the role of individual differences in propensity for MS-C and CMP in practice of a fundamental laparoscopic skill and in laparoscopic performance during the OSCE. Furthermore, this study examined whether individual differences during practice of a fundamental laparoscopic skill were predictive of laparoscopic performance during the OSCE. METHODS Overall, 77 final-year undergraduate medical students completed the movement specific reinvestment scale, an assessment tool that quantifies the propensity for MS-C and CMP. Participants were trained to proficiency on a fundamental laparoscopic skill. The number of trials to reach proficiency was measured, and completion times were recorded during early practice, later practice, and the OSCE. RESULTS There was a trend for CMP to be negatively associated with the number of trials to reach proficiency (p = 0.064). A higher propensity for CMP was associated with fewer trials to reach proficiency (β = -0.70, p = 0.023). CMP and MS-C did not significantly predict completion times in the OSCE (p > 0.05). Completion times in early practice (β = 0.05, p = 0.016) and later practice (β = 0.47, p < 0.001) and number of trials to reach proficiency (β = 0.23, p = 0.003) significantly predicted completion times in the OSCE. CONCLUSION It appears that a higher propensity for CMP predicts faster rates of learning of a fundamental laparoscopic skill. Furthermore, laparoscopic performance during practice is indicative of laparoscopic performance in the challenging conditions of the OSCE. The lack of association between the 2 dimensions of movement specific reinvestment and performance during the OSCE is explained using the theory of reinvestment as a framework. Overall, consideration of personality differences and individual differences in ability during practice could help inform the development of individualized surgical training programs.

Effects of transcranial direct current stimulation over the Broca’s area on tongue twister production

Abstract Purpose: The present study aimed to explore the short-term effect of anodal transcranial direct current stimulation (tDCS) on tongue twister production. Method: Thirty healthy native Cantonese adult speakers were randomly assigned to the anodal tDCS group or the sham tDCS group. Anodal tDCS of 2 mA was applied over the Broca’s area of the brain. The stimulation lasted for 20 min for the anodal tDCS group and 30 s for the sham tDCS group. The participants were instructed to produce a list of tongue twisters before, immediately after and 4 h after tDCS. Result: Speech rate and response accuracy measured immediately after stimulation were significantly faster and higher, respectively, than before stimulation. Although there was no change in speech rate measured at 4 h after stimulation, response accuracy at that time point was significantly lower than that measured immediately after stimulation. However, there were no significant differences between the anodal tDCS and sham tDCS groups in either speech rate or response accuracy. Conclusion: The findings revealed that a single session of anodal tDCS over the Broca’s area did not significantly improve speech production during tongue twister production.

Time course of EEG activities in continuous tracking task: A pilot study

BACKGROUND Motor learning is important in daily activities and rehabilitation, but its neural mechanism has been only investigated using some simple tasks with limited motor involvement. OBJECTIVE This study aimed to gain better understanding of the neural dynamics during motor learning by investigating the time course of electroencephalogram (EEG) activities in the continuous tracking task with more motor components. METHODS One participant performed 16 trials of the continuous tracking task on Day1 and Day2 respectively. The 16-channel EEG signals were recorded and analyzed in both the resting and active states. RESULTS The tracking performance improved from Day1 to Day2. Regarding the EEG, it was found that the relative amplitude in the individual alpha band (IAB) decreased locally over primary motor cortex from the resting state to the active state on both days, and this reduction was more focused on the left primary motor cortex on Day2 compared to Day1. Moreover, in the active state the alpha coherence between central and frontal areas also significantly increased from Day1 to Day2. CONCLUSION Time course of alpha activities may explain the tracking performance enhancement from Day1 to Day2. Future work will include more participants to extend the validity of current results.

Reliable Detection of Implicit Waveform-Specific Learning in Continuous Tracking Task Paradigm

Implicit waveform-specific (IWS) learning during a typical continuous tracking task paradigm has been reported for decades, as evidenced by better tracking improvement on the repeated segment of a specific target waveform than random segments. However, the occurrence of the IWS learning in such a task paradigm has been challenged by several unsuccessful results in recent literature. This research concerns reliable detection of the induced IWS learning and to this end, proposes to use the similarity between the cursor and the target along the direction corresponding to the waveform pattern as the performance measure. A 3-day experiment designed with full examination on IWS learning including a practice phase, an immediate test phase and a consolidation test phase after 24 hours was conducted to validate the feasibility and sensitivity of the Pearson’s correlation coefficient on the vertical movement rv in this study. Experiment results indicate that rv is more sensitive in detecting the IWS learning in all phases compared to the conventional root mean square error (RMSE) performance measure. The findings confirm the importance of the performance measure in implicit learning research and the similarity measure in accordance with the waveform could be promising for waveform-specific learning detection in this paradigm.

Time course of EEG activities in continuous tracking task: a pilot study

Abstract Motor learning is crucial to surgical skills enhancement, but its neural mechanism has been investigated only using some simple tasks with limited motor involvement. This study aimed to gain more understanding of the neural dynamics during motor learning by investigating the time course of electroencephalogram (EEG) activities in the continuous tracking task that involves more motor components. One participant performed 16 trials of the continuous tracking task on Day1 and Day2 respectively. The 16-channel EEG signals were recorded and analyzed in both the resting and active states. Results showed that the tracking performance improved from Day1 to Day2. Regarding the EEG, it was found that the relative amplitude in the individual alpha band (IAB) decreased locally over primary motor cortex from the resting state to the active state on both days, and this reduction was more focused on the left primary motor cortex on Day2 compared to Day1. Moreover, in the active state the alpha coherence between central and frontal areas also significantly increased from Day1 to Day2. Time course of alpha activities may explain the tracking performance enhancement from Day1 to Day2. Future work will include more participants to extend the validity of current results.