Humans have an individual profile of the electroencephalographic power spectra at the 8 to 16Hz frequency during non–rapid eye movement sleep that is stable over time and resistant to experimental ...perturbations. We tested the hypothesis that this electroencephalographic “fingerprint” is genetically determined, by recording 40 monozygotic and dizygotic twins during baseline and recovery sleep after prolonged wakefulness. We show a largely greater similarity within monozygotic than dizygotic pairs, resulting in a heritability estimate of 96%, not influenced by sleep need and intensity. If replicated, these results will establish the electroencephalographic profile during sleep as one of the most heritable traits of humans. Ann Neurol 2008
When linking in time electrical stimulation of the peripheral nerve with transcranial magnetic stimulation (TMS), the excitability of the motor cortex can be modulated to evoke clear inhibition, as ...reflected by the amplitude decrement in the motor-evoked potentials (MEPs). This specific property, designated short-latency afferent inhibition (SAI), occurs when the nerve-TMS interstimulus interval (ISI) is approximately 25 ms and is considered to be a corticothalamic phenomenon. The aim of the present study was to use the electroencephalographic (EEG) responses to navigated-TMS coregistration to better characterize the neuronal circuits underlying SAI. The present experimental set included magnetic resonance imaging (MRI)-navigated TMS and 60-channel TMS-compatible EEG devices. TMS-evoked EEG responses and MEPs were analyzed in eight healthy volunteers; ISIs between median nerve and cortical stimulation were determined relative to the latency of the individual N20 component of the somatosensory-evoked potential (SEP) obtained after stimulation of the median nerve. ISIs from the latency of the N20 plus 3 ms and N20 plus 10 ms were investigated. In all experimental conditions, TMS-evoked EEG responses were characterized by a sequence of negative deflections peaking at approximately 7, 44, and 100 ms alternating with positive peaks at approximately 30, 60, and 180 ms post-TMS. Moreover, ISI N20+3 ms modulated both EEG-evoked activity and MEPs. In particular, it inhibited MEP amplitudes, attenuated cortical P60 and N100 responses, and induced motor cortex beta rhythm selective decrement of phase locking. The findings of the present experiment suggest the cortical origin of SAI that could result from the cortico-cortical activation of GABAergic-mediated inhibition onto the corticospinal neurons modulated by cholinergic activation able to reducing intralaminar inhibition and promoting intracolumnar inhibition.
Background:
Early and affordable identification of subjects with amnestic mild cognitive impairment (aMCI) who will convert to Alzheimer’s disease (AD) is a major scientific challenge.
Objective:
To ...investigate the neurophysiological hallmarks of sensorimotor cortex function in aMCI under the hypothesis that some may represent the plastic rearrangements induced by neurodegeneration, hence predictors of future conversion to AD. We sought to determine (1) whether the sensorimotor network shows peculiar alterations in patients with aMCI and (2) if sensorimotor network alterations predict long-term disease progression at the individual level.
Methods:
We studied several transcranial magnetic stimulation (TMS)-electroencephalogram (EEG) parameters of the sensorimotor cortex in a group of patients with aMCI and followed them for 6 years. We then identified aMCI who clinically converted to AD prodromal to AD-MCI (pAD-MCI) and those who remained cognitively stable non-prodromal to AD-MCI (npAD-MCI).
Results:
Patients with aMCI showed reduced motor cortex (M1) excitability and disrupted EEG synchronization decreased intertrial coherence (ITC) in alpha, beta and gamma frequency bands compared to the control subjects. The degree of alteration in M1 excitability and alpha ITC was comparable between pAD-MCI and npAD-MCI. Importantly, beta and gamma ITC impairment in the stimulated M1 was greater in pAD-MCI than npAD-MCI. Furthermore, an additional parameter related to the waveform shape of scalp signals, reflecting time-specific alterations in global TMS-induced activity stability of the dipolar activity (sDA), discriminated npAD-MCI from MCI who will convert to AD.
Discussion:
The above mentioned specific cortical changes, reflecting deficit of synchronization within the cortico-basal ganglia-thalamo-cortical loop in aMCI, may reflect the pathological processes underlying AD. These changes could be tested in larger cohorts as neurophysiological biomarkers of AD.
Objective
Mild cognitive impairment (MCI) is a condition intermediate between physiological brain aging and dementia. Amnesic‐MCI (aMCI) subjects progress to dementia (typically to Alzheimer‐Dementia ...= AD) at an annual rate which is 20 times higher than that of cognitively intact elderly. The present study aims to investigate whether EEG network Small World properties (SW) combined with Apo‐E genotyping, could reliably discriminate aMCI subjects who will convert to AD after approximately a year.
Methods
145 aMCI subjects were divided into two sub‐groups and, according to the clinical follow‐up, were classified as Converted to AD (C‐MCI, 71) or Stable (S‐MCI, 74).
Results
Results showed significant differences in SW in delta, alpha1, alpha2, beta2, gamma bands, with C‐MCI in the baseline similar to AD. Receiver Operating Characteristic(ROC) curve, based on a first‐order polynomial regression of SW, showed 57% sensitivity, 66% specificity and 61% accuracy(area under the curve: AUC=0.64). In 97 out of 145 MCI, Apo‐E allele testing was also available. Combining this genetic risk factor with Small Word EEG, results showed: 96.7% sensitivity, 86% specificity and 91.7% accuracy(AUC=0.97). Moreover, using only the Small World values in these 97 subjects, the ROC showed an AUC of 0.63; the resulting classifier presented 50% sensitivity, 69% specificity and 59.6% accuracy. When different types of EEG analysis (power density spectrum) were tested, the accuracy levels were lower (68.86%).
Interpretation
Concluding, this innovative EEG analysis, in combination with a genetic test (both low‐cost and widely available), could evaluate on an individual basis with great precision the risk of MCI progression. This evaluation could then be used to screen large populations and quickly identify aMCI in a prodromal stage of dementia. Ann Neurol 2018 Ann Neurol 2018;84:302–314
Strokes causing similar lesions and clinical states can be followed by diverse regains of neurological functions, indicating that the clinical recovery can depend on individual modulating factors. A ...promising line to disclose these factors, to finally open new therapeutic strategies, is to search for individual indices of recovery prognosis. Here, we pursued on strengthening the value of acute phase electrophysiological biomarkers for poststroke functional recovery in a wide group of patients. We enrolled 120 patients affected by a monohemispheric stroke within the middle cerebral artery territory (70 left and 50 right damages) and collected the NIH stroke scale (NIHSS) score in the acute phase (T0, median 4 days) and chronic follow-up (T1, median 6 months). At T0, we executed electrophysiological noninvasive assessment (19-channel electroencephalography (EEG) or 28 channels per side magnetoencephalography (MEG)) of brain activity at rest by means of band powers in the contra- and ipsilesional hemispheres (CLH, ILH) or the homologous area symmetry (HArS). Low-band (2-6 Hz) HArS entered the regression model for predicting the stabilized clinical state (p<0.001), with bilateral impairment correlated with a poor outcome. Present data strengthen the fact that low-band impairment of homologous ipsi- and contralesional hemispheric regions in the acute stroke indicate a negative prognosis of clinical recovery.
Highlights • Motor cortex has enhanced excitability in AD and SIVD patients with respect to control subjects and it is plastically rearranged, without significant differences between the two demented ...groups. • In the whole sample of subjects examined a significant direct correlation between parameters associated to cortical excitability and those associated to cortical plasticity is evident. • Common compensatory mechanisms may act in different kind of dementing diseases.
Applying the Delphi method, this study aims at characterizing the perceptions and needs of physicians, individuals with hemophilia, and their caregivers in relation to the management of routine ...visits during regular follow-ups. A single structured questionnaire, prepared by an advisory board, was administered to 139 participants, comprising hemophilia treaters, patients and caregivers, during the period from May to June 2023. Agreement (defined following the Delphi method as developed by RAND Corporation) was reached on several topics. The Principal Component Analysis methods identified the four most relevant areas where consensus was reached among the interviewees, underscoring the necessity for in-depth discussions during routine visits: (1) medical aspects related to symptoms, life-limitations, pain, etc.; (2) non-medical related aspects (ambitions, lifestyle, network, etc.); (3) logistical-organizational aspects (home-hospital distance, alternative modalities of communication); and (4) visit duration and telemedicine integration. The results of both the Delphi and Principal Component Analysis underline that the care of individuals with hemophilia extends beyond merely prescribing drugs or treatment regimens. Instead, it necessitates consideration of numerous variables from both therapeutic and non-therapeutic domains, all of which are deemed important for the holistic management of the individuals. As a result, these aspects are routinely discussed and addressed during visits.
Decision often implies a utilitarian choice based on personal gain, even at the expense of damaging others. Despite the social implications of utilitarian behavior, its neurophysiological bases ...remain largely unknown. To assess how the human brain controls utilitarian behavior, we delivered transcranial direct current stimulation (tDCS) over the ventral prefrontal cortex (VPC) and over the occipital cortex (OC) in 78 healthy subjects. Utilitarian judgment was assessed with the moral judgment task before and after tDCS. At baseline, females provided fewer utilitarian answers than males for personal moral dilemmas (p = .007). In males, VPC-tDCS failed to induce changes and in both genders OC-tDCS left utilitarian judgments unchanged. In females, cathodal VPC-tDCS tended to decrease whereas anodal VPC-tDCS significantly increased utilitarian responses (p = .005). In males and females, reaction times for utilitarian responses significantly decreased after cathodal (p<.001) but not after anodal (p = .735) VPC-tDCS. We conclude that ventral prefrontal tDCS interferes with utilitarian decisions, influencing the evaluation of the advantages and disadvantages of each option in both sexes, but does so more strongly in females. Whereas cathodal tDCS alters the time for utilitarian reasoning in both sexes, anodal stimulation interferes more incisively in women, modifying utilitarian reasoning and the possible consequent actions. The gender-related tDCS-induced changes suggest that the VPC differentially controls utilitarian reasoning in females and in males. The gender-specific functional organization of the brain areas involved in utilitarian behavior could be a correlate of the moral and social behavioral differences between the two sexes.
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