Challenge to Promote Change: The Neural Basis of the Contextual Interference Effect in Young and Older Adults

Abstract

Motor performance deteriorates with age. Hence, studying the effects of different training types on performance improvement is particularly important. Here, we investigated the neural correlates of the contextual interference (CI) effect in 32 young (YA; 16 female) and 28 older (OA; 12 female) human adults. Participants were randomly assigned to either a blocked or a random practice schedule, practiced three variations of a bimanual visuomotor task over 3 d, and were retested 6 d later. Functional magnetic resonance imaging data were acquired during the first and last training days and during retention. Although the overall performance level was lower in OA than YA, the typical CI effects were observed in both age groups, i.e., inferior performance during acquisition but superior performance during retention for random relative to blocked practice. At the neural level, blocked practice showed higher brain activity in motor-related brain regions compared with random practice across both age groups. However, although activity in these regions decreased with blocked practice in both age groups, it was either preserved (YA) or increased (OA) as a function of random practice. In contrast, random compared with blocked practice resulted in greater activations in visual processing regions across age groups. Interestingly, in OA, the more demanding random practice schedule triggered neuroplastic changes in areas of the default mode network, ultimately leading to better long-term retention. Our findings may have substantial implications for the optimization of practice schedules, and rehabilitation settings in particular. In aging societies, it is critically important to understand how motor skills can be maintained or enhanced in older adults, with the ultimate goal to prolong functional independence. Here, we demonstrated that a more challenging random as opposed to a blocked practice environment temporarily reduced performance during the acquisition phase but resulted in lasting benefits for skill retention. In older adults, learning success was critically dependent on reduction of activation in areas of the default mode network, pointing to plastic functional changes in brain regions that are vulnerable to aging effects. The random practice context led to increased economy of brain activity and better skill retention. This provides new perspectives for reversing the negative consequences of aging.

Aging and brain plasticity

“…More specifically, a decrease in GABA levels is indicative of a release from inhibition to promote mechanisms of long-term potentiation, cortical plasticity and learning [ 6 , 8 ]. Whereas previous work reported this GABA modulation to occur in the motor cortex [Floyer-Lea A, et al 2006] we observed it in the broader occipital territory, containing brain areas involved in processing of the stimulus structure and the movement-generated visual feedback, made available during practice (such as primary and secondary visual cortex and posterior precuneus), as exemplified by task-related functional magnetic resonance imaging [ 7 ]. Conversely, the less demanding blocked-practice schedule consisted of repeated presentation of stimuli, resulting in attenuated neuronal responses (repetition suppression) and enhanced GABA levels.…”

“…A retention test was carried out 6 days later. With MRS, we determined the GABA levels before and after training in primary sensorimotor cortex and occipital cortex, because our previous work showed considerable brain activity in both visual and motor processing regions, in agreement with the unique visuomotor signature of this tracking task [ 7 ]. We found that (1) the behavioral data confirmed the typical contextual interference effects, i.e., random as compared to blocked practice led to temporary inferior performance levels during the acquisition phase but superior skill retention in both age groups, (2) the MRS data demonstrated a training-induced decrease in occipital GABA level during random practice but an increased GABA level during blocked practice and this effect was even more pronounced in older adults [ 6 ].…”

Principles of Neurorehabilitation After Stroke Based on Motor Learning and Brain Plasticity Mechanisms

“…These results point to more efficient retrieval of motor memory due to variable practice (Lin et al, 2011). More complex bimanual visuomotor tasks that were practiced randomly have shown modality-specific activation patterns that led to the recruitment of areas related to visual processing (Pauwels et al, 2018). The effect of variable practice might be related to the strong link between the neuromodulatory systems that control neuronal plasticity and novelty, for instance, the dopaminergic (Redgrave and Gurney, 2006), cholinergic (Hasselmo et al, 1996), and noradrenergic systems (Vankov et al, 1995), which are used by the brainstem activation system for controlling the global state of arousal (Gur et al, 2007).…”

Neural Mechanisms of the Contextual Interference Effect and Parameter Similarity on Motor Learning in Older Adults: An EEG Study

“…The result of several studies has shown that the random practice results in poorer performance during acquisition but superior performance during retention and transfer compared to the blocked practice (Shea and Morgan, 1979;Magill and Hall, 1990;Brady, 1998). The result of studies has also indicated that older adults may benefit from this type of practice condition like younger performers (Lin et al, 2010(Lin et al, , 2012Pauwels et al, 2015Pauwels et al, , 2018Sidaway et al, 2016;Chalavi et al, 2018). However, some studies did not show the superior performance of random practice during retention in older adults (de Souza et al, 2015).…”