Interference effects between memory systems in the acquisition of a skill

Exploring pain interference with motor skill learning in humans: A systematic review

Motor learning underpins successful motor skill acquisition. Although it is well known that pain changes the way we move, it’s impact on motor learning is less clear. The aim of this systematic review was to synthesize evidence on the impact of experimental and clinical pain on task performance and activity-dependent plasticity measures across learning and explore these findings in relation to different pain and motor learning paradigms. Five databases were searched: Web of Science, Scopus, MEDLINE, Embase and CINAHL. Two reviewers independently screened the studies, extracted data, and assessed risk of bias using the Cochrane ROB2 and ROBIN-I. The overall strength of evidence was rated using the GRADE guidelines. Due to the heterogeneity of study methodologies a narrative synthesis was employed. Twenty studies were included in the review: fifteen experimental pain and five clinical pain studies, covering multiple motor paradigms. GRADE scores for all outcome measures suggested limited confidence in the reported effect for experimental pain and clinical pain, on motor learning. There was no impact of pain on any of the task performance measures following acquisition except for ‘accuracy’ during a tongue protrusion visuomotor task and ‘timing of errors’ during a motor adaptation locomotion task. Task performance measures at retention, and activity dependent measures at both acquisition and retention showed conflicting results. This review delivers a detailed synthesis of research studies exploring the impact of pain on motor learning. This is despite the challenges provided by the heterogeneity of motor learning paradigms, outcome measures and pain paradigms employed in these studies. The results highlight important questions for further research with the goal of strengthening the confidence of findings in this area.

Wakeful rest during storage and consolidation enhances priming effects for those with acquired memory impairment

A period of rest after learning results in better explicit memory for the material than a period of unrelated mental activity. This study investigated whether the same applies to priming. Thirty-four people with memory impairments due to acquired brain injury took part. In a repeated measures design, participants studied word lists; then either engaged in a relaxation technique (wakeful rest condition) or completed visuo-spatial tasks (control condition); and finally completed two priming tasks. Priming effects were significantly larger in the wakeful rest condition. This result is difficult to explain in terms of some of the explanations used to account for the benefits of wakeful rest on explicit memory, and alternative explanations are considered. One possibility is that the attentional demands of the control task resulted in inhibition of activity in neocortical areas associated with perception that contributed to the priming effect. The findings have implications for memory rehabilitation. Acquired memory impairments typically impact on explicit memory, and implicit memory is often relatively intact. It is important to find ways of enabling those with more severe explicit impairments to make best use of their implicit memory as a way of compensating for the deficits in their explicit memory.