Benefit of interleaved practice of motor skills is associated with changes in functional brain network topology that differ between younger and older adults

C-SMB 2.0: Integrating over 25 years of motor sequencing research with the Discrete Sequence Production task

An exhaustive review is reported of over 25 years of research with the Discrete Sequence Production (DSP) task as reported in well over 100 articles. In line with the increasing call for theory development, this culminates into proposing the second version of the Cognitive framework of Sequential Motor Behavior (C-SMB 2.0), which brings together known models from cognitive psychology, cognitive neuroscience, and motor learning. This processing framework accounts for the many different behavioral results obtained with the DSP task and unveils important properties of the cognitive system. C-SMB 2.0 assumes that a versatile central processor (CP) develops multimodal, central-symbolic representations of short motor segments by repeatedly storing the elements of these segments in short-term memory (STM). Independently, the repeated processing by modality-specific perceptual and motor processors (PPs and MPs) and by the CP when executing sequences gradually associates successively used representations at each processing level. The high dependency of these representations on active context information allows for the rapid serial activation of the sequence elements as well as for the executive control of tasks as a whole. Speculations are eventually offered as to how the various cognitive processes could plausibly find their neural underpinnings within the intricate networks of the brain.

Effect of Practice Structure and Feedback Frequency on Voice Motor Learning in Older Adults

OBJECTIVES

The long-term goal of this research is to advance the rehabilitation of voice disorders through the study and development of efficacious treatment regimes based upon motor learning principles. This study examined the effect of contextual interference (CI) of practice structure with knowledge of results (KR) feedback on motor learning of a novel voice task, "Twang," by hypophonic, novice, and expert older adults.

STUDY DESIGN

Prospective, randomized controlled mixed design.

METHODS

A total of 92 adults, age 55-80, recruited from the following motor skill levels: 1) Hypophonic voice; 2) Novice-untrained vocalists; 3) Expert-trained vocalists were randomly assigned to four different interventions and examined during acquisition, retention, and transfer phases of motor learning. Participants from each skill-level practiced the novel task, "Twang," according to the randomly assigned Practice Structure/KR combinations: 1) Blocked practice/100%KR; 2) Blocked practice/55% KR; 3) Random practice/100%KR; 4) Random practice/55% KR.

RESULTS

During the motor performance phase, our results mirrored those reported in the limb motor learning literature for CI: A Blocked practice structure enhanced short-term effects of motor acquisition for novice, expert, and hypophonic subjects. The only significant result for KR occurred when paired with Random Practice in the hypophonic subject group: 100% KR paired with Blocked practice increased motor performance, but degraded motor learning.

CONCLUSIONS

Fundamental motor learning principles were explored within the context of a voice training paradigm. Practice with a high CI and low frequency of KR degraded performance during short-term acquisition but enhanced long-term performance effects of motor learning. Voice clinicians and teachers may benefit by implementing motor learning theory into practice during training and treatment sessions.

Contextual interference enhances motor learning through increased resting brain connectivity during memory consolidation

Increasing contextual interference (CI) during practice benefits learning, making it a desirable difficulty. For example, interleaved practice (IP) of motor sequences is generally more difficult than repetitive practice (RP) during practice but leads to better learning. Here we investigated whether CI in practice modulated resting-state functional connectivity during consolidation. 26 healthy adults (11 men/15 women, age = 23.3 ± 1.3 years) practiced two sets of three sequences in an IP or RP condition over 2 days, followed by a retention test on Day 5 to evaluate learning. On each practice day, functional magnetic resonance imaging (fMRI) data were acquired during practice and also in a resting state immediately after practice. The resting-state fMRI data were processed using independent component analysis (ICA) followed by functional connectivity analysis, showing that IP on Day 1 led to greater resting connectivity than RP between the left premotor cortex and left dorsolateral prefrontal cortex (DLPFC), bilateral posterior cingulate cortices, and bilateral inferior parietal lobules. Moreover, greater resting connectivity after IP than RP on Day 1, between the left premotor cortex and the hippocampus, amygdala, putamen, and thalamus on the right, and the cerebellum, was associated with better learning following IP. Mediation analysis further showed that the association between enhanced resting premotor-hippocampal connectivity on Day 1 and better retention performance following IP was mediated by greater task-related functional activation during IP on Day 2. Our findings suggest that the benefit of CI to motor learning is likely through enhanced resting premotor connectivity during the early phase of consolidation.