1,721,518 research outputs found
The dark side of Alzheimer's disease. Neglected physiological biomarkers of brain hyperexcitability and abnormal consciousness level
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EEG, ERPs, and EROs in patients with cognitive deficits due to progressive neurodegenerative diseases: The dark side of the precision medicine
No full textMany millions of patients worldwide live with age-related progressive neurodegenerative diseases such as Alzheimer's, Parkinson's, Lewy body, and others belonging to severe cognitive deficits and disabilities in the activities of daily living (i.e., dementia) until death after a disease course of 10–15 years (Lemstra et al., 2017; Teipel et al., 2022). Indeed, no effective disease-blocking therapy is available to date. These diseases are caused by insufficient homeostasis of potentially neurotoxic proteins (e.g., amyloid, phospho tau, alpha-synuclein, TDP-43, light neurofibrillary chains) that progressively accumulate in the brain, affecting synaptic transmission and the generation and conduction of action potentials until neural loss (Lemstra et al., 2017; Jack Jr et al., 2018; Scott et al., 2022; Teipel et al., 2022).Alzheimer's Association International Society to Advance Alzheimer's Research and Treatment ; Global Brain Consortium ; ISTAART ; Alzheimer's Associatio
The I.F.A.S.T. model allows the prediction of conversion to Alzheimer disease in patients with mild cognitive impairment with high degree of accuracy.
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Frontoparietal cortex controls spatial attention through modulation of anticipatory alpha rhythms.
No full textA dorsal frontoparietal network, including regions in intraparietal sulcus (IPS) and frontal eye field (FEF), has been hypothesized to control the allocation of spatial attention to environmental stimuli. One putative mechanism of control is the desynchronization of electroencephalography (EEG) alpha rhythms (approximately 8-12 Hz) in visual cortex in anticipation of a visual target. We show that brief interference by repetitive transcranial magnetic stimulation (rTMS) with preparatory activity in right IPS or right FEF while subjects attend to a spatial location impairs identification of target visual stimuli approximately 2 s later. This behavioral effect is associated with the disruption of anticipatory (prestimulus) alpha desynchronization and its spatially selective topography in parieto-occipital cortex. Finally, the disruption of anticipatory alpha rhythms in occipital cortex after right IPS- or right FEF-rTMS correlates with deficits of visual identification. These results support the causal role of the dorsal frontoparietal network in the control of visuospatial attention, and suggest that this is partly exerted through the synchronization of occipital visual neuron
Working memory of somatosensory stimuli: an fMRI study.
No full textIn a previous study, we have shown that passive recognition of tactile geometrical shapes (i.e. no exploratory movement) engages prefrontal and premotor areas in addition to somatosensory regions (Savini et al., 2010). In the present study we tested the hypothesis that these regions are involved not only in the perception but also during working memory of such somatic information.We performed functional magnetic resonance imaging (fMRI) during the execution of N-BACK tasks, with 2D geometrical shapes blindly pressed on the subjects' right hand palm. Three conditions with increasing memory load (0-BACK, 1-BACK, 2-BACK) were used. Results showed that primary somatosensory area (SI), secondary somatosensory area (SII) and bilateral Insula were active in all conditions, confirming their importance in coding somatosensory stimuli. Activation of fronto-parietal circuit in supplementary motor area (SMA), right superior parietal lobe (rSPL), bilateral middle frontal gyrus, left inferior frontal gyrus, and right superior frontal sulcus was significantly larger during 1-BACK and 2-BACK than 0-BACK. Left superior parietal lobe and right frontal eye field showed a higher activation during the 2-BACK than 0-BACK. Finally, SMA and rSPL were characterized by a statistically significant higher activation during 2-BACK than 1-BACK, revealing their sensitivity to the memory load. These results suggest that working memory of tactile geometrical shapes (no exploratory movement) involves a complex circuit of modal and supramodal fronto-parietal areas. © 2012 Elsevier B.V
Clinical neurophysiology of aging brain: From normal aging to neurodegeneration
No full textPhysiological brain aging is characterized by a loss of synaptic contacts and neuronal apoptosis that provokes age-dependant decline of sensory processing, motor performance, and cognitive function. Neural redundancy and plastic remodelling of brain networking, also secondary to mental and physical training, promotes maintenance of brain activity in healthy elderly for everyday life and fully productive affective and intellectual capabilities. However, age is the main risk factor for neurodegenerative disorders such as Alzheimer's disease (AD) that impact on cognition. Oscillatory electromagnetic brain activity is a hallmark of neuronal network function in various brain regions. Modern neurophysiological techniques including electroencephalography (EEG), event-related potential (ERP), magnetoencephalography (MEG), and transcranial magnetic stimulation (TMS) can accurately index normal and abnormal brain aging to facilitate non-invasive analysis of cortico-cortical connectivity and neuronal synchronization of firing and coherence of rhythmic oscillations at various frequencies. The present review provides a perspective of these issues by assaying different neurophysiological methods and integrating the results with functional brain imaging findings. It is concluded that discrimination between physiological and pathological brain aging clearly emerges at the group level, with applications at the individual level also suggested. Integrated approaches utilizing neurophysiological techniques together with biological markers and structural and functional imaging are promising for large-scale, low-cost and non-invasive evaluation of at-risk populations. Practical implications of the methods are emphasized. © 2007 Elsevier Ltd. All rights reserved
Improved realistic Laplacian estimate of highly-sampled EEG potentials with regularization techniques
No full textDynamic functional cortical network associated with human unilateral voluntary movements
No full textInformational digest bulletin from san raffaele foundation and tosinvest sanità (No. 21). A new quantitative approach of the evaluation of "Tonic" Cortical EEG rhythms in adults with down syndrome and in adults with an impairment of awareness - Persistent Vegetative State (PVS)
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