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Motor functions improve during childhood and adolescence, but little is still known about the development of cortical motor circuits during early life. To elucidate the neurophysiological hallmarks of motor cortex development, we investigated the differences in motor cortical excitability and connectivity between healthy children, adolescents, and adults by means of navigated suprathreshold motor cortex transcranial magnetic stimulation (TMS) combined with high-density electroencephalography (EEG). We demonstrated that with development, the excitability of the motor system increases, the TMS-evoked EEG waveform increases in complexity, the magnitude of induced activation decreases, and signal spreading increases. Furthermore, the phase of the oscillatory response to TMS becomes less consistent with age. These changes parallel an improvement in manual dexterity and may reflect developmental changes in functional connectivity. Hum Brain Mapp 38:2599-2615, 2017. © 2017 Wiley Periodicals, Inc., (© 2017 Wiley Periodicals, Inc.)

Objective: To evaluate neurophysiological features of M1 excitability and plasticity in Subcortical Ischemic Vascular Dementia (SIVD), by means of a TMS mapping study., Methods: Seven SIVD and nine AD patients, along with nine control subjects were tested. The M1 excitability was studied by resting thresholds, area and volume of active cortical sites for forearm and hand's examined muscles. For M1 plasticity, coordinates of the hot-spot and the center of gravity (CoG) were evaluated. The correlation between the degree of hyperexcitability and the amount of M1 plastic rearrangement was also calculated., Results: Multivariate analysis of excitability measures demonstrated similarly enhanced cortical excitability in AD and SIVD patients with respect to controls. SIVD patients showed a medial and frontal shift of CoG from the hot-spot, not statistically different from that observed in AD. A significant direct correlation was seen between parameters related to cortical excitability and those related to cortical plasticity., Conclusions: The results suggest the existence of common compensatory mechanisms in different kind of dementing diseases supporting the idea that cortical hyperexcitability can promote cortical plasticity., Significance: This study characterizes neurophysiological features of motor cortex excitability and plasticity in SIVD, providing new insights on the correlation between cortical excitability and plasticity., (Copyright © 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.)

The aim of this study was to evaluate neurophysiological features of M1 excitability and plasticity in Subcortical Ischemic Vascular Dementia (SIVD), by means of TMS mapping technique. Seven SIVD and nine AD patients, along with nine control subjects were tested. The M1 excitability was studied by resting thresholds, area and volume of active cortical sites for forearm and hand’s examined muscles. For M1 plasticity, coordinates of the hot-spot and the center of gravity (CoG) were evaluated. The correlation between the degree of hyperexcitability and the amount of M1 plastic rearrangement was also calculated. Multivariate analysis of excitability measures demonstrated similarly enhanced cortical excitability in AD and SIVD patients with respect to controls. SIVD patients showed a medial and frontal shift of CoG from the hot-spot, not statistically different from that observed in AD. A significant direct correlation was seen between parameters related to cortical excitability and those related to cortical plasticity. The results suggest the existence of common compensatory mechanisms in different kind of dementing diseases supporting the idea that cortical hyperexcitability can promote cortical plasticity. This study characterizes neurophysiological features of motor cortex excitability and plasticity in SIVD, providing new insights on the correlation between cortical excitability and plasticity. [ABSTRACT FROM AUTHOR]

Motor cortex hyperexcitability as a possible reflection of restorative plasticity is a well defined neurophysiological feature of Alzheimer’s disease (AD), probably related to its severity and progression. Vascular Dementia is the second most common type of dementia and it is mainly represented by an homogeneous subtype that is the Subcortical Ischemic Vascular Dementia (SIVD). To date, only few studies investigating motor cortex functionality in SIVD have been published and in none of them the TMS motor cortex mapping technique was used. The aim of this investigation was then test and better characterize neurophysiological features of motor cortex excitability and plasticity in SIVD by means of a TMS mapping study. Results showed that even though in SIVD the motor cortex was found to be hyperexcitable and functionally rearranged however the neurophysiological profile identified did not lead to a clear distinction between vascular and neurodegenerative dementia. On the other hand, in the examined population a significant direct correlation was seen between parameters associated to cortical excitability and those related to cortical plasticity, supporting the idea that cortical hyperexcitability can promote cortical plasticity and shading light on possible rehabilitative strategies. [ABSTRACT FROM AUTHOR]