The effects of alteration of effector and side of movement on the contingent negative variation

From preparation to post-processing: Insights into evoked and induced cortical activity during pre-cued motor reactions in children and adolescents

INTRODUCTION

The motor system undergoes significant development throughout childhood and adolescence. The contingent negative variation (CNV), a brain response reflecting preparation for upcoming actions, offers valuable insights into these changes. However, previous CNV studies of motor preparation have primarily focused on adults, leaving a gap in our understanding of how cortical activity related to motor planning and execution matures in children and adolescents.

METHODS

The study addresses this gap by investigating the maturation of motor preparation, pre-activation, and post-processing in 46 healthy, right-handed children and adolescents aged 5-16 years. To overcome the resolution limitations of previous studies, we combined 64-electrode high-density Electroencephalography (EEG) and advanced analysis techniques, such as event-related potentials (ERPs), mu-rhythm desynchronization as well as source localization approaches. The combined analyses provided an in-depth understanding of cortical activity during motor control.

RESULTS

Our data showed that children exhibited prolonged reaction times, increased errors, and a distinct pattern of cortical activation compared to adolescents. The findings suggest that the supplementary motor area (SMA) plays a progressively stronger role in motor planning and response evaluation as children age. Additionally, we observe a decrease in sensory processing and post-movement activity with development, potentially reflecting increased efficiency. Interestingly, adolescent subjects, unlike young adults in previous studies, did not yet show contralateral activation of motor areas during the motor preparation phase (late CNV).

CONCLUSION

The progressive increase in SMA activation and distinct cortical activation patterns in younger participants suggest immature motor areas. These immature regions might be a primary cause underlying the age-related increase in motor action control efficiency. Additionally, the study demonstrates a prolonged maturation of cortical motor areas, extending well into early adulthood, challenging the assumption that motor control is fully developed by late adolescence. This research, extending fundamental knowledge of motor control development, offers valuable insights that lay the foundation for understanding and treating motor control difficulties.

Electrophysiological evidence for lateralization of preparatory motor processes

Event-related potentials were recorded during a warned choice reaction time task in which the warning signal was informative (it signaled the specific response to be required) or uninformative (it gave no response-specific information). The response signal specified a key press with either the middle or the ring finger of the left or the right hand. The informative warning signal facilitated reaction time in two separate protocols. The contingent negative variation elicited following the informative warning signal was larger than that following the uninformative warning signal, and this effect was larger over the left hemisphere than over the right hemisphere. This finding gives converging evidence that preparatory motor processes are predominantly lateralized to the dominant hemisphere.

Experimental disentangling of spatial-compatibility and interhemispheric-relay effects in simple reaction time (Poffenberger paradigm)

Spatial-compatibility effects can be obtained in simple reaction time (SRT) provided that spatially distinct responses are frequently required. Since this effect is limited to trials with relatively long reaction times (RTs), Hommel (1996b) proposed that if the response does not occur shortly after stimulus detection, then the spatial code of the stimulus can interfere with that of the response. A series of experiments is reported showing that (a) spatial compatibility in SRT to lateralized stimuli is not an alternative, but rather a complementary, explanation to interhemispheric transfer time (contrary to what Hommel surmised), and (b) the spatial compatibility component is essentially limited to the first trial after shifting response preparation from one-half of the visual fields to the other, suggesting a mechanism akin to an orienting response.