Brain Activation in Motor Sequence Learning Is Related to the Level of Native Cortical Excitability

Abstract

Cortical excitability may be subject to changes through training and learning. Motor training can increase cortical excitability in motor cortex, and facilitation of motor cortical excitability has been shown to be positively correlated with improvements in performance in simple motor tasks. Thus cortical excitability may tentatively be considered as a marker of learning and use-dependent plasticity. Previous studies focused on changes in cortical excitability brought about by learning processes, however, the relation between native levels of cortical excitability on the one hand and brain activation and behavioral parameters on the other is as yet unknown. In the present study we investigated the role of differential native motor cortical excitability for learning a motor sequencing task with regard to post-training changes in excitability, behavioral performance and involvement of brain regions. Our motor task required our participants to reproduce and improvise over a pre-learned motor sequence. Over both task conditions, participants with low cortical excitability (CElo) showed significantly higher BOLD activation in task-relevant brain regions than participants with high cortical excitability (CEhi). In contrast, CElo and CEhi groups did not exhibit differences in percentage of correct responses and improvisation level. Moreover, cortical excitability did not change significantly after learning and training in either group, with the exception of a significant decrease in facilitatory excitability in the CEhi group. The present data suggest that the native, unmanipulated level of cortical excitability is related to brain activation intensity, but not to performance quality. The higher BOLD mean signal intensity during the motor task might reflect a compensatory mechanism in CElo participants.

Opposing effects of dopamine antagonism in a motor sequence task—tiapride increases cortical excitability and impairs motor learning

“…The present findings complement the results of a previous study (Lissek et al, 2013 ) in which we demonstrated in healthy participants that CE remained unchanged after learning and training of an identical motor sequence task. Moreover, the inverse relation of CE and learning performance found in the tiapride group corresponds to the findings of a study using the DA-agonist cabergoline, which for a simple motor practice task of thumb movements showed an increase in practice-dependent plasticity combined with a decrease in CE (Meintzschel and Ziemann, 2006 ).…”

“…Motor training can increase motor CE (Abbruzzese et al, 1996 ; Koeneke et al, 2006 ; Cirillo et al, 2010 , 2011 ), while increased motor CE positively correlates with performance improvements in simple motor tasks (Muellbacher et al, 2001 ; Ziemann et al, 2001 ). However, a recent study using a complex motor task found no increase of CE after task training and performance (Lissek et al, 2013 ), which is in line with two previous studies that used less complex tasks (Ziemann et al, 2001 ; Smyth et al, 2010 ). Therefore, it is debatable whether changes in CE in motor cortex can be considered indicators of motor learning and use-dependent plasticity.…”

“…Our findings indicate that the post-training increase in CE is associated with DA-antagonism, since a comparable change was found neither in the placebo group nor in the participants of a previous study using the same motor task in untreated participants (Lissek et al, 2013 ). This tiapride-induced enhancement reflected in significantly reduced inhibition and increased facilitation.…”

“…In contrast to these findings, our results suggest that at least for complex motor sequence learning, training alone does not alter CE, since in the placebo group CE remained unchanged. Different experimental designs and methods of calculating CE might account for the diverging findings, which we discussed in detail in a previous report (Lissek et al, 2013 ).…”

Representation of time interval entrained by periodic stimuli in the visual thalamus of pigeons

“…To address this question, we used the pigeon as an animal model and the nucleus dorsolateralis anterior thalami (DLA) as the target brain area. The pigeon is a common animal model for behavioral and neurobiological studies of time-dependent cognitive tasks, such as interval timing ( Kalenscher et al, 2006 ), sequence learning ( Helduser et al, 2013 ; Lissek et al, 2013 ), and delayed matching-to-sample ( Browning et al, 2011 ). Furthermore, to achieve foraging and safe flight successfully in diverse environments, birds have developed a complex visual system that is superior to that of most vertebrates ( Shimizu and Watanabe, 2012 ; Wylie et al, 2015 ).…”