Biology subjects

Maceira-Elvira, P.

Publications and source records attributed to Maceira-Elvira, P..

3 recordsLinked to original sources

bioRxiv2023

Not only a matter of age: Machine learning-based characterization of the differential effect of brain stimulation on skill acquisition

Brain stimulation shows potential at enhancing cognitive and motor functions in humans. However, multiple studies assessing its effects on behavior show heterogeneous results, especially in healthy older subjects. We propose a new method to predict an individuals likelihood and the magnitude of the benefit from stimulation, based on the baseline performance of a sequential motor task, framed in the context of their age. Our results show a differential effect of stimulation, in which individuals with less efficient learning mechanisms benefit from stimulation, while those possessing optimal learning strategies resent a detrimental effect. Importantly, this differential effect was determined by ones ability to integrate task-relevant information at the early stages of training, and not the age. This study paves the way towards the personalized application of stimulation to maximize its effects, and constitutes the first steps to implement an individualized translational clinical intervention, based on the state of the neural system. TeaserAge notwithstanding, brain stimulation is most effective in deficient neural systems, while being detrimental to optimal systems Visual abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=121 SRC="FIGDIR/small/544579v1_ufig1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@bcfab0org.highwire.dtl.DTLVardef@ee55e9org.highwire.dtl.DTLVardef@14a7519org.highwire.dtl.DTLVardef@14de600_HPS_FORMAT_FIGEXP M_FIG C_FIG Main findingAnodal transcranial direct current stimulation (atDCS), applied over the hand representation of the motor cortex concomitant to the training of a sequential motor sequence, has differential effects as a function of the recipients ability to integrate task-relevant information at the early stages of training. Stimulation benefits individuals with seemingly less efficient learning mechanisms, enabling the rapid storage of the spatial coordinates of the motor sequence and an accelerated optimization of the accuracy of execution. In contrast, individuals possessing optimal learning mechanisms experience detrimental effects of stimulation, leading to drops in the accuracy of execution.

neuroscience↗

bioRxiv2022

LTP-like noninvasive striatal brain stimulation enhances striatal activity and motor skill learning in humans

The stimulation of deep brain structures has thus far only been possible with invasive methods. Transcranial electrical temporal interference stimulation (tTIS) is a novel, noninvasive technology that might overcome this limitation. The initial proof-of-concept was obtained through modeling, physics experiments and rodent models. Here, we show for the first time successful noninvasive neuromodulation of the striatum via tTIS in humans using computational modeling, fMRI studies and behavioral evaluations. Theta-burst patterned striatal tTIS increased activity in the striatum and associated motor network. Furthermore, striatal tTIS enhanced motor performance, especially in healthy older participants as they have lower natural learning skills than younger subjects. These findings place tTIS as exciting new method to target deep brain structures in humans noninvasively, thus enhancing our understanding of their functional roles. Moreover, our results lay the groundwork for innovative, noninvasive treatment strategies for brain disorders in which deep striatal structures play key pathophysiological roles.

neuroscience↗

bioRxiv2021

Black-box testing in motor sequence learning

During learning of novel motor sequences, practice leads to the consolidation of hierarchical structures, namely motor chunks, facilitating the accurate execution of sequences at increasing speeds. Recent studies show that such hierarchical structures are largely represented upstream of the primary motor cortex in the motor network, suggesting their function to be more related to the encoding, storage, and retrieval of sequences rather than their sole execution. We isolated different components of motor skill acquisition related to the consolidation of spatiotemporal features and followed their evolution over training. We found that optimal motor skill acquisition relies on the storage of the spatial features of the sequence in memory, followed by the optimization of its execution and increased execution speeds (i.e., a shift in the speed-accuracy trade-off) early in training, supporting the model proposed by Hikosaka in 1999. Contrasting the dynamics of these components during ageing, we identified less-than-optimal mechanisms in older adults explaining the observed differences in performance. We applied noninvasive brain stimulation in an attempt to support the aging brain to compensate for these deficits. The present study found that anodal direct current stimulation applied over the motor cortex restored the mechanisms involved in the consolidation of spatial features, without directly affecting the speed of execution of the sequence. This led older adults to sharply improve their accuracy, resulting in an earlier yet gradual emergence of motor chunks. The results suggest the early storage of the sequence in memory, largely independent of motor practice, is crucial for an optimal motor acquisition and retrieval of this motor behavior. Nevertheless, the consolidation of optimal temporal patterns, detected as motor chunks at a behavioral level, is not a direct consequence of storing the sequence elements, but rather of motor practice.

neuroscience↗