Abstracts / Clinical Neurophysiology 128 (2017) e178–e303
MR tractography, functional and effective connectivity measures on MRI (BOLD), EEG and other electrophysiological techniques. Results: Integrating structural, typically MRI-derived connectomic information into analysis of functional brain connectivity, i.e., measured by EEG, MEG or magnetic stimulation, enhances our understanding of interregional interaction after stroke (e.g., Finger et al. PLoS Comput Biol. 2016 Aug 9;12(8):e1005025; Schulz et al. Stroke. 2016 Feb;47(2):482–9). The impact of corticospinal tract damage is substantial. Enhanced connectivity between parietal and primary motor cortex appears to be related to better functional outcome. Discussion: Structurally informed analyses of functional connectivity help identifying key hubs and edges that cause symptoms and subserve recovery after stroke. Limitations are discussed. Conclusions: Combining MRI-based connectomics and electrophysiological measures advances our understanding of damaged neural networks and recovery in humans. Significance: Whenever possible, a multimodal, combined structural and electrophysiological approach should be chosen when investigating neural networks in patients. doi:10.1016/j.clinph.2017.07.042
S32 Investigation method of neurodegeneration through brain connectivity modulation—Paolo Maria Rossini (Università Cattolica del Sacro Cuore, Institute of Neurology, Rome, Italy) Human behavior and cognition are characterized by engagement of functional distributed networks within the brain. Such networks organization is especially significant for higher functions including abstract reasoning, memory and action planning and requires a high degree of intra-modal and inter-modal integration of information flow arriving from several, different and often remote brain sources. It will be reported the topological changes in functional brain networks during physiological and pathological aging by graph theoretical analysis of resting-state EEG recordings. Furthermore, evidences illustrate possible way to investigated neurodegeneration such as in Alzheimer’s disease through the study of the brain connectivity modulation. Theoretical graph approach is a promising tool, able to catch some global and local features in the functional connectivity patterns estimated from the EEG along the physiological and pathological brain aging. Applying modern graph theory looking for EEG pathological brain aging from both cortical sources powers and connectivity to a large cohort allowed us to demonstrate a continuous line connecting normal elderly subjects and demented patients passing through MCI. Altogether, we concluded that coupling measures can discriminate cortical network features distinguishing physiological from pathological neurodegenerative brain aging. Keywords: Functional coupling, Alzheimer, EEG doi:10.1016/j.clinph.2017.07.043
S33 Network intervention modelling in Alzheimer’s disease— Willem De Haan (VU University Medical Center, Department of Neurology, Amsterdam, The Netherlands) Objective: This presentation aims to provide a personal perspective on how brain connectivity research may get closer to obtaining a clinical role. I will argue that network intervention modeling, which unites the strengths of network analysis and computational
modeling, is a great candidate for this purpose, as it can offer an attractive test environment in which positive and negative influences on network integrity can be explored, with the ultimate aim to find effective countermeasures against neurodegenerative network damage. Recent evidence suggests that neuronal hyperactivity has a prominent role in AD pathophysiology, making it a potentially interesting therapeutic target. However, although neuronal activity can be manipulated by various (non-)pharmacological means, intervening in a highly integrated system that depends on complex dynamics can produce counterintuitive or adverse effects. Dynamic network modeling may serve as a virtual test ground for developing effective interventions. Methods: To explore this approach, a large-scale neural mass model with human brain topology was used to simulate the temporal evolution of AD-like, activity-dependent network degeneration. In addition, defense strategies that enhance or diminish neuronal excitability were tested against the degeneration process, targeting excitatory and inhibitory neurons combined or separately. Outcome measures consisted of various quantitative markers describing oscillatory, connectivity and topological features of the network. Results: Over time, the various interventions produced diverse large-scale network effects. Contrary to our hypothesis, the most successful strategy was a selective stimulation of all excitatory neurons in the network; it substantially prolonged the preservation of network integrity. Conclusion: The results of this study imply that functional network damage due to pathological neuronal activity in AD can be opposed by adjusting neuronal excitability levels. Significance: The present approach may help to explore and explain therapeutic effects aimed at preserving or restoring neuronal network integrity, and thereby contribute to making betterinformed intervention choices in future clinical trials. Keywords: Connectivity, Brain networks, Neurophysiology, Graph theory, Modeling, Alzheimer, Dementia, Neuronal hyperactivity doi:10.1016/j.clinph.2017.07.044
Assistant/technicians Session A34 ‘‘Inching” method in localizing compression in case of ulnar nerve—Tünde Peterman 1, Péter Diószeghy 2, Ferenc Mechler 1 (1 University of Debrecen, Department of Neurology, Debrecen, Hungary, 2 Andras Josa Teaching Hospital, Department of Neurology, Nyíregyháza, Hungary) Introduction: Inching method enables the precise localization of the ulnar nerve compression in the region of the elbow. Aim: To use inching method as a routine measure in every case when ulnar nerve compression by the elbow is suspected. Method: Supramaximal stimulation is used starting from the most distal point towards the proximal ones. For registration bipolar surface electrodes are used. Results: The lesion can be localized very precisely and the abnormalities can be detected even early in the subclinical phase. Conclusion: According to our experiences inching method can be implemented easily and it is also easy to master. Today with the spreading of endoscopic technology we use the method as a routine.