Signal Processing techniques and brain imaging in TMS EEG signals

TMS allows to give a control input into specific target nodes in a complex network, characterize the dynamics, capture the responses physiologically via EEG and ultimally relate those to the behaviour (e.g. muscle twitch) as shown in the study VI. The study I can be considered an example of asymmetric hyperexcitability, accessed by TMS mapping technique, that could represent a mechanism of brain functional plasticity in a chronic disorder, such as congenital hydrocephalus. The study II presented suggest that in Alzheimer's Disease (AD) and Subcortical Ischemic Vascular Dementia (SIVD) the motor cortex is functionally rearranged and its excitability is enhanced, supporting the idea that cortical hyperexcitability can promote cortical plasticity. In the study III by using EEG-TMS co-registration, was clearly demonstrated that the sensorimotor system in mild AD is strongly hyperexcitable and could be preliminary interpreted as a compensatory mechanism allowing the preservation of sensorimotor programming and execution over a long period despite disease progression. The study IV confirms the hypothesis that bidirectional neural interface could be of primary interest to redirect cortical areas deprived of their original function because of amputation toward restorative neuroplasticity. In the study V the results suggest that a multimodal approach is helpful for advanced study of the characteristics of excitability and connectivity morpho/functional physiological and pathological aging. Indeed, it allows identifying anomalies in the connections between different brain areas of being possibly causative mechanisms involved in the pathogenesis of Alzheimer's disease. From the study VI clearly emerge that EEG co-registrated with TMS is a unique toolbox to evaluate not only the connectivity between areas as results of an inductive procedure but actually to measure -for the first time- the strength of connections existing between the dynamically activated areas. This is crucial to guarantee innovative paradigms of rehabilitation in stroke patients and amputees.