Encoding attentional states during visuomotor adaptation

Reciprocal facilitation between mental and visuomotor rotations

Humans exhibit remarkably complex cognitive abilities and adaptive behavior in daily life. Cognitive operation in the "mental workspace," such as mentally rotating a piece of luggage to fit into fixed trunk space, helps us maintain and manipulate information on a moment-to-moment basis. Skill acquisition in the "sensorimotor workspace," such as learning a new mapping between the magnitude of new vehicle movement and wheel turn, allows us to adjust our behavior to changing environmental or internal demands to maintain appropriate motor performance. While this cognitive and sensorimotor synergy is at the root of adaptive behavior in the real world, their interplay has been understudied due to a divide-and-conquer approach. We evaluated whether a separate domain-specific or common domain-general operation drives mental and sensorimotor rotational transformations. We observed that participants improved the efficiency of mental rotation speed after the visuomotor rotation training, and their learning rate for visuomotor adaptation also improved after their mental rotation training. Such bidirectional transfer between two widely different tasks highlights the remarkable reciprocal plasticity and demonstrates a common transformation mechanism between two intertwined workspaces. Our findings urge the necessity of an explicitly integrated approach to enhance our understanding of the dynamic interdependence between cognitive and sensorimotor mechanisms.

Inconsistent attentional contexts impair re-learning following gradual visuomotor adaptation

One of the brain's primary functions is to promote actions in dynamic, distracting environments. Because distractions divert attention away from our primary goals, we learn to maintain accurate actions under sensory and cognitive distractions. Visuomotor adaptation refers to learning processes that restore performance when sensorimotor capacities or environmental conditions are abruptly or gradually altered. Prior work showed that learning to counteract an abrupt perturbation while performing either a single or dual task, referred to as the attentional context, led to better and faster re-learning when the same attentional context was reinstated at recall. This suggested that the attentional context was associated with visuomotor adaptation and used as a contextual cue during recall. The current study investigated whether attentional context was associated with visuomotor adaptation to a gradual perturbation, which limits awareness of errors. During adaptation, participants reached to targets while learning to counteract a visuomotor rotation that increased from 0 to 45 deg by 0.3 deg each trial, with or without performing a secondary task. Re-learning was impaired when the attentional context changed between adaptation and recall (Experiment 1), even compared to when the secondary task was only performed during the early or late half of adaptation (Experiment 2). Changing the secondary task between adaptation and recall did not impair re-learning, indicating that the effect was attentional-context-dependent, rather than task-specific (Experiment 3). These findings further highlight the importance of cognitive factors, such as attention, in visuomotor adaptation and have implications for learning and rehabilitation paradigms.

Age-related enhancement in visuomotor learning by a dual-task

Many daily activities require performance of multiple tasks integrating cognitive and motor processes. While the fact that both processes go through deterioration and changes with aging has been generally accepted, not much is known about how aging interacts with stages of motor skill acquisition under a cognitively demanding situation. To address this question, we combined a visuomotor adaptation task with a secondary cognitive task. We made two primary findings beyond the expected age-related performance deterioration. First, while young adults showed classical dual-task cost in the early motor learning phase dominated by explicit processes, older adults instead strikingly displayed enhanced performance in the later stage, dominated by implicit processes. For older adults, the secondary task may have facilitated a shift to their relatively intact implicit learning processes that reduced reliance on their already-deficient explicit processes during visuomotor adaptation. Second, we demonstrated that consistently performing the secondary task in learning and re-learning phases can operate as an internal task-context and facilitate visuomotor memory retrieval later regardless of age groups. Therefore, our study demonstrated age-related similarities and differences in integrating concurrent cognitive load with motor skill acquisition which, may in turn, contributes to the understanding of a shift in balance across multiple systems.

The effect of age on visuomotor learning processes

Knowing where our limbs are in space is essential for moving and for adapting movements to various changes in our environments and bodies. The ability to adapt movements declines with age, and age-related cognitive decline can explain a decreased ability to adopt and deploy explicit, cognitive strategies in motor learning. Age-related sensory decline could also lead to a reduced fidelity of sensory position signals and error signals, each of which can affect implicit motor adaptation. Here we investigate two estimates of limb position; one based on proprioception, the other on predicted sensory consequences of movements. Each is considered a measure of an implicit adaptation process and may be affected by both age and cognitive strategies. Both older (n = 38) and younger (n = 42) adults adapted to a 30° visuomotor rotation in a centre-out reaching task. We make an explicit, cognitive strategy available to half of participants in each age group with a detailed instruction. After training, we first quantify the explicit learning elicited by instruction. Instructed older adults initially use the provided strategy slightly less than younger adults but show a similar ability to evoke it after training. This indicates that cognitive explanations for age-related decline in motor learning are limited. In contrast, training induced much larger shifts of state estimates of hand location in older adults compared to younger adults. This is not modulated by strategy instructions, and appears driven by recalibrated proprioception, which is almost twice as large in older adults, while predictions might not be updated in older adults. This means that in healthy aging, some implicit processes may be compensating for other changes to maintain motor capabilities, while others also show age-related decline (data: https://osf.io/qzhmy).

Altering attention to split-belt walking increases the generalization of motor memories across walking contexts

Little is known about the impact of attention during motor adaptation tasks on how movements adapted in one context generalize to another. We investigated this by manipulating subjects' attention to their movements while exposing them to split-belt walking (i.e., legs moving at different speeds), which is known to induce locomotor adaptation. We hypothesized that reducing subjects' attention to their movements by distracting them as they adapted their walking pattern would facilitate the generalization of recalibrated movements beyond the training environment. We reasoned that awareness of the novel split-belt condition could be used to consciously contextualize movements to that particular situation. To test this hypothesis, young adults adapted their gait on a split-belt treadmill while they observed visual information that either distracted them or made them aware of the belt's speed difference. We assessed adaptation and aftereffects of spatial and temporal gait features known to adapt and generalize differently in different environments. We found that all groups adapted similarly by reaching the same steady-state values for all gait parameters at the end of the adaptation period. In contrast, both groups with altered attention to the split-belts environment (distraction and awareness groups) generalized their movements from the treadmill to overground more than controls, who walked without altered attention. This was specifically observed in the generalization of step time (temporal gait feature), which might be less susceptible to online corrections during walking overground. These results suggest that altering attention to one's movements during sensorimotor adaptation facilitates the generalization of movement recalibration.NEW & NOTEWORTHY Little is known about how attention affects the generalization of motor recalibration induced by sensorimotor adaptation paradigms. We showed that altering attention to movements on a split-belt treadmill led to greater adaptation effects in subjects walking overground. Thus our results suggest that altering patients' attention to their actions during sensorimotor adaptation protocols could lead to greater generalization of corrected movements when moving without the training device.

The role of attention in motor control and learning

Performing and learning motor behaviors are fundamental to everyday life. The relations between perceptual input and motor output have been studied and are well understood for simple experimental settings. Recent findings, however, suggest that motor actions also critically depend on cognitive factors; these influences are most notable in complex environments that place high demands on attention and memory. In this review, the role of various aspects of attention in motor control is discussed, focusing on the following points: (1) recent findings concerning interactions between attentional resources and motor skill acquisition, (2) the consistency of attentional states (divided versus focused) and motor memory retrieval, and (3) the locus of attention (internal versus external) and motor performance. These findings collectively highlight the interplay between attention and motor systems, which in turn has practical implications for developing and improving motor training and rehabilitation programs.

Age and Cognitive Stress Influences Motor Skill Acquisition, Consolidation, and Dual-Task Effect in Humans

This study examined motor skill learning using a weight-bearing and cognitive-motor dual-task that incorporated unexpected perturbations and measurements of cognitive function. Forty young and 24 older adults performed a single-limb weight bearing task with novel speed, resistance, and cognitive dual task conditions to assess motor skill acquisition, retention and transfer. Subjects performed a cognitive dual task: summing letters in one color/orientation (simple) or two colors/orientations (complex). Increased cognitive load diminished the rate of skill acquisition, decreased transfer to new conditions, and increased error rate during an unexpected perturbation; however, young adults had a dual-task benefit from cognitive load. Executive function predicted 80% of the variability in dual-task performance. Although initial learning of a weight-bearing cognitive-motor dual-task was poor, longer term goals of improved dual-task effect and retention emerged.

Impaired visuomotor generalization by inconsistent attentional contexts

In daily life, people are constantly presented with situations in which they have to learn and acquire new motor skills in complex environments, where attention is often distracted by other events. Being able to generalize and perform the acquired motor action in different environments is a crucial part of visuomotor learning. The current study examined whether attentional distraction impairs generalization of visuomotor adaptation or whether consistent distraction can operate as an internal cue to facilitate generalization. Using a dual-task paradigm combining visuomotor rotational adaptation and an attention-demanding secondary task, we showed that switching the attentional context from training (dual-task) to generalization (single-task) reduced the range of transfer of visuomotor adaptation to untrained directions. However, when consistent distraction was present throughout training and generalization, visuomotor generalization was equivalent to without distractions at all. Furthermore, this attentional context-dependent generalization was evident even when sensory modality of distractions differed between training and generalization. Therefore, the general nature of the dual tasks, rather than the specific stimuli, is associated with visuomotor memory and serves as a critical cue for generalization. Taken together, we demonstrated that attention plays a critical role during sensorimotor adaptation in selecting and associating multisensory signals with motor memory. This finding provides insight into developing learning programs that are generalizable in complex daily environments.NEW & NOTEWORTHY Learning novel motor actions in complex environments with attentional distraction is a critical function. Successful motor learning involves the ability to transfer the acquired skill from the trained to novel environments. Here, we demonstrate attentional distraction does not impair visuomotor adaptation. Rather, consistency in the attentional context from training to generalization modulates the degree of transfer to untrained locations. The role of attention and memory must, therefore, be incorporated into existing models of visuomotor learning.

Automaticity and Flexibility of S–R Retrieval During Priming

Learned associations between stimuli and responses (S–R associations) make important contributions to behavioral and neural priming. The current study investigated the automaticity and flexibility of these S–R associations and whether the global task context in which they occur modulates the impact of S–R retrieval on priming. Participants engaged in a semantic repetition priming task in which S–R retrieval is known to influence priming. Across participants, repetition priming occurred in global task contexts (i.e., combination of activated task sets) that either remained consistent or shifted across time. In the stable context group, the global task context at study matched that at test, whereas in the shifting context group, the global task context at study differed from that at test. Results revealed that the stability of the global task context did not affect the magnitude of S–R contributions to priming and that S–R contributions to priming were significant in both the stable and shifting context groups. These results highlight the robustness of S–R contributions to priming and indicate that S–R associations can flexibly transfer across changes in higher-level task states.

Long lasting attentional-context dependent visuomotor memory

Using a dual-task paradigm, we recently reported that visuomotor adaptation acquired under distraction of a secondary attention-demanding discrimination task could be remembered only when a similar distraction was present. In contrast, when tested without the distracting task, performance reverted to untrained levels (Song & Bédard, 2015). Here, we demonstrated that this newfound paradoxical benefit of consistent dual-task context lasts over 1 day, such that visuomotor memory retrieval is enhanced under conditions where it is more difficult to engage in attentional selection of the motor task. Furthermore, this long-term effect was evident even when the task type or sensory modality of the secondary task differed between initial adaptation and the delayed recall on the next day. We conclude that attentional diversion by performing a dual-task forms a long-term vital context for visuomotor memory independent of external contexts without taxing capacity limited attention. (PsycINFO Database Record