The human dorsal premotor cortex facilitates the excitability of ipsilateral primary motor cortex via a short latency cortico-cortical route

Background Motor information in the brain is transmitted from the dorsal premotor cortex (PMd) to the primary motor cortex (M1), where it is further processed and relayed to the spinal cord to eventually generate muscle movement. However, how information from the PMd affects M1 processing and the final output is unclear. Here, we applied intermittent theta burst stimulation (iTBS) to the PMd to alter cortical excitability not only at the application site but also at the PMd projection site of M1. We aimed to determine how PMd iTBS–altered information changed M1 processing and the corticospinal output. Methods In total, 16 young, healthy participants underwent PMd iTBS with 600 pulses (iTBS600) or sham-iTBS600. Corticospinal excitability, short-interval intracortical inhibition (SICI), and intracortical facilitation (ICF) were measured using transcranial magnetic stimulation before and up to 60 min after stimulation. Results Corticospinal excitability in M1 was significantly greater 15 min after PMd iTBS600 than that after sham-iTBS600 (p = 0.012). Compared with that after sham-iTBS600, at 0 (p = 0.014) and 15 (p = 0.037) min after iTBS600, SICI in M1 was significantly decreased, whereas 15 min after iTBS600, ICF in M1 was significantly increased (p = 0.033). Conclusion Our results suggested that projections from the PMd to M1 facilitated M1 corticospinal output and that this facilitation may be attributable in part to decreased intracortical inhibition and increased intracortical facilitation in M1. Such a facilitatory network may inform future understanding of the allocation of resources to achieve optimal motion output.

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Rostrocaudal functional gradient among the pre-dorsal premotor cortex, dorsal premotor cortex and primary motor cortex in goal-directed motor behaviour

European Journal of Neuroscience ◽

10.1111/ejn.13254 ◽

2016 ◽

Vol 43 (12) ◽

pp. 1569-1589 ◽

Cited By ~ 7

Author(s):

Yoshihisa Nakayama ◽

Tomoko Yamagata ◽

Eiji Hoshi

Keyword(s):

Motor Cortex ◽

Primary Motor Cortex ◽

Premotor Cortex ◽

Motor Behaviour ◽

Dorsal Premotor Cortex ◽

Functional Gradient

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Bilateral primary motor cortex circuitry is modulated due to theta burst stimulation to left dorsal premotor cortex and bimanual training

Brain Research ◽

10.1016/j.brainres.2015.05.028 ◽

2015 ◽

Vol 1618 ◽

pp. 61-74 ◽

Cited By ~ 4

Author(s):

Jason L. Neva ◽

Michael Vesia ◽

Amaya M. Singh ◽

W. Richard Staines

Keyword(s):

Motor Cortex ◽

Primary Motor Cortex ◽

Premotor Cortex ◽

Dorsal Premotor Cortex ◽

Theta Burst Stimulation ◽

Burst Stimulation ◽

Bimanual Training ◽

Theta Burst

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No impact of functional connectivity of the motor system on the resting motor threshold: A replication study

10.1101/2020.10.26.354886 ◽

2020 ◽

Author(s):

Melina Engelhardt ◽

Darko Komnenić ◽

Fabia Roth ◽

Leona Kawelke ◽

Carsten Finke ◽

...

Keyword(s):

Functional Connectivity ◽

Motor Cortex ◽

Primary Motor Cortex ◽

Premotor Cortex ◽

Corticospinal Excitability ◽

Grey Matter Volume ◽

Dominant Hemisphere ◽

Motor Threshold ◽

Dorsal Premotor Cortex ◽

Resting Motor Threshold

AbstractThe physiological mechanisms of corticospinal excitability and factors influencing its measurement with transcranial magnetic stimulation are still poorly understood. A recent study reported an impact of functional connectivity between the primary motor cortex and dorsal premotor cortex on the resting motor threshold of the dominant hemisphere. We aimed to replicate these findings in a larger sample of 38 healthy right-handed subjects with data from both hemispheres. Resting-state functional connectivity was assessed between the primary motor cortex and five a-priori defined motor-relevant regions on each hemisphere as well as interhemispherically between both primary motor cortices. Following the procedure by the original authors, we included age, the cortical grey matter volume and coil to cortex distance as further predictors in the analysis. We report replication models for the dominant hemisphere as well as an extension to data from both hemispheres and support the results with Bayes factors. Functional connectivity between the primary motor cortex and dorsal premotor cortex did not explain variability in the resting motor threshold and we obtained moderate evidence for the absence of this effect. In contrast, coil to cortex distance could be confirmed as an important predictor with strong evidence. These findings contradict the previously proposed effect, thus questioning the notion of the dorsal premotor cortex playing a major role in modifying corticospinal excitability.

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