Proactive and retroactive transfer of middle age adults in a sequential motor learning task

Post-error slowing during motor sequence learning under extrinsic and intrinsic error feedback conditions

Post-error slowing, described as an error-corrective index of response binding during motor sequence learning, has only been demonstrated in the serial reaction time task under conditions where extrinsic error feedback is presented. The present experiment investigated whether post-error slowing is dependent on, or is influenced by, extrinsic error feedback. Thirty participants (14 females, Mage = 21.9 ± 1.8 years) completed the serial reaction time task with or without presentation of extrinsic error feedback. Post-error slowing was observed following response error whether feedback was presented or not. However, presentation of extrinsic error feedback increased post-error slowing across practice and extended the number of responses that were slowed following an error. There was no evidence of feedback effects on motor sequence learning or explicit awareness. Instead, feedback appeared to function as a performance factor that reduced response error rates relative to no feedback conditions. These findings illustrate that post-error slowing in motor sequence learning is not reliant on or a result of presentation of extrinsic error information. More specific to the serial reaction time task paradigm, the present findings demonstrate that the common practice of presenting error feedback is not necessary for investigating motor sequence learning unless the aim is to maintain low error rate. However, doing so might inflate reaction time in latter training blocks.

Age-related effects of repeated task switching in a novel voluntary gait adaptability task

Age-related effects of task switching have been extensively studied based on cognitive tasks and simple motor tasks, but less on complex cognitive-motor tasks involving dynamic balance control while walking. The latter tasks may especially be difficult and relevant for older adults in terms of safe mobility in daily life. The aim of the present study was, therefore, to examine age-related changes in task-switching adaptability using a novel voluntary gait adaptability test protocol. Fifteen healthy young (27.5 ± 2.9 years) and 16 healthy old (70.9 ± 7.6 years) adults carried out 2 different visual target stepping tasks (either target avoidance or stepping) twice in a block (A-B-A-B, 2 min per task; three blocks in total) without any intrablock breaks. Our results showed that old adults showed significantly more step errors both in Tasks A and B as well as more interference effects than young adults. Age-related differences in step accuracy were significant in the anterior-posterior direction both in Task A and B but not in the mediolateral direction. Both in step errors and accuracy, no interaction effects of age and trial were shown. Our results suggest that old adults could not cope with rapid and direct task changes in our voluntary gait adaptability task as young adults. Since the significant main effect of trial for Task B, but not Task A appears to be due to different task complexity, further studies may determine the effect of task complexity or task switch timing.

Early sleep after action observation and motor imagery training boosts improvements in manual dexterity

The systematic observation and imagination of actions promotes acquisition of motor skills. Furthermore, studies demonstrated that early sleep after practice enhances motor learning through an offline stabilization process. Here, we investigated behavioral effects and neurodynamical correlates of early sleep after action observation and motor imagery training (AO + MI-training) on motor learning in terms of manual dexterity. Forty-five healthy participants were randomized into three groups receiving a 3 week intervention consisting of AO + MI-training immediately before sleeping or AO + MI-training at least 12 h before sleeping or a control stimulation. AO + MI-training implied the observation and motor imagery of transitive manual dexterity tasks, whereas the control stimulation consisted of landscape video-clips observation. Manual dexterity was assessed using functional tests, kinematic and neurophysiological outcomes before and after the training and at 1-month follow-up. AO + MI-training improved manual dexterity, but subjects performing AO + MI-training followed by early sleep had significantly larger improvements than those undergoing the same training at least 12 h before sleeping. Behavioral findings were supported by neurodynamical correlates during motor performance and additional sleep-dependent benefits were also detected at 1 month follow-up. These findings introduce a new approach to enhance the acquisition of new motor skills or facilitate recovery in patients with motor impairments.

Memory Traces Diminished by Exercise Affect New Learning as Proactive Facilitation

Exercise enhances cognitive function through increased neurogenesis but can also cause neurogenesis-induced forgetting. It remains unclear whether the diminished memory traces are completely forgotten. Our goals were to determine whether spatial memory is diminished by exercise, and if so, whether the memory is completely gone or whether only the local details disappear but not the acquired strategy. Two-month-old male C57BL/6J mice were trained on a spatial memory task using the Morris water maze and tested to determine that they had learned the platform location. Another mouse group received no training. Half the mice in each group then exercised on a running wheel, while the other half remained sedentary in home cages. After 4 weeks of this, previously trained mice were tested for their retention of the platform location. All mice were then subjected to the task, but the platform was located in a different position (reversal learning for previously trained mice). We found that exercise significantly facilitated the forgetting of the first platform location (i.e., diminished spatial memory) but also significantly enhanced reversal learning. Compared with mice that received no pre-exercise training, mice that had been previously trained, even those in the exercise group that had decreased recall, showed significantly better performance in the reversal learning test. Activation of new adult-born neurons was also examined. Although newborn neuron activation between groups that had or had not received prior task training was not different, activation was significantly higher in exercise groups than in sedentary groups after the probe test for reversal learning. These results indicated that the experience of pre-exercise training equally facilitated new learning in the sedentary and exercise groups, even though significantly lower memory retention was found in the exercise group, suggesting rule-based learning in mice. Furthermore, newborn neurons equally participated in similar and novel memory acquisition.

Explicit instructions and consolidation promote rewiring of automatic behaviors in the human mind

One major challenge in human behavior and brain sciences is to understand how we can rewire already existing perceptual, motor, cognitive, and social skills or habits. Here we aimed to characterize one aspect of rewiring, namely, how we can update our knowledge of sequential/statistical regularities when they change. The dynamics of rewiring was explored from learning to consolidation using a unique experimental design which is suitable to capture the effect of implicit and explicit processing and the proactive and retroactive interference. Our results indicate that humans can rewire their knowledge of such regularities incidentally, and consolidation has a critical role in this process. Moreover, old and new knowledge can coexist, leading to effective adaptivity of the human mind in the changing environment, although the execution of the recently acquired knowledge may be more fluent than the execution of the previously learned one. These findings can contribute to a better understanding of the cognitive processes underlying behavior change, and can provide insights into how we can boost behavior change in various contexts, such as sports, educational settings or psychotherapy.

The enduring effects of depressive thoughts on working memory

BACKGROUND

Depressive thoughts are known to persist in persons with depressed mood leading to rumination and exacerbation of depressive symptoms. What has not yet been examined is whether this persistence of depressive thoughts can lead to impairment of working memory (WM).

METHODS

We assessed whether receiving a WM task featuring depressive cues could bias performance on a subsequent, non-depressive WM task for dysphoric individuals (DIs) compared to non-DIs.

RESULTS

DIs showed significantly attenuated performance on the WM task with depressive cues compared to non-DIs. Further, when DIs were given the WM task with depressive cues first, they showed deficits on a second WM task without depressive cues, compared to DIs given the non-depressive WM task first and non-DIs in either condition.

LIMITATIONS

Unselected recruitment procedures did not permit balanced sample sizes in each group. Future research is needed to assess whether these results extend to a clinically depressed sample and whether WM deficits are the consequence of depressed mood, or a risk factor for the development and maintenance of depressed mood.

CONCLUSIONS

Results suggest that, for DIs, the influence of depressive cues on performance transfers to subsequent tasks in which these cues are no longer present. These results support the hypothesis that when depressive thoughts are part of depressed persons' conscious experience, cognitive deficits arise. Further, these results suggest an ecologically-relevant mechanism by which day-to-day cognitive deficits in depression can develop.