In EEG/fMRI correlation studies it is common to consider the fMRI BOLD as filtered version of the EEG alpha power. Here the question is addressed whether other EEG frequency components may affect the ...correlation between alpha and BOLD. This was done comparing the statistical parametric maps (SPMs) of three different filter models wherein either the free or the standard hemodynamic response functions (HRF) were used in combination with the full spectral bandwidth of the EEG.
EEG and fMRI were co-registered in a 30 min resting state condition in 15 healthy young subjects. Power variations in the delta, theta, alpha, beta and gamma bands were extracted from the EEG and used as regressors in a general linear model. Statistical parametric maps (SPMs) were computed using three different filter models, wherein either the free or the standard hemodynamic response functions (HRF) were used in combination with the full spectral bandwidth of the EEG.
Results show that the SPMs of different EEG frequency bands, when significant, are very similar to that of the alpha rhythm. This is true in particular for the beta band, despite the fact that the alpha harmonics were discarded. It is shown that inclusion of EEG frequency bands as confounder in the fMRI–alpha correlation model has a large effect on the resulting SPM, in particular when for each frequency band the HRF is extracted from the data.
We conclude that power fluctuations of different EEG frequency bands are mutually highly correlated, and that a multi frequency model is required to extract the SPM of the frequency of interest from EEG/fMRI data. When no constraints are put on the shapes of the HRFs of the nuisance frequencies, the correlation model looses so much statistical power that no correlations can be detected.
•We explored the relationship between event-related potentials, deep grey matter atrophy and cognition in MS.•Cortex volume emerged as the most significant predictor of the P300 amplitude.•The ...amygdala and hippocampal volumes were found to influence P300 latency.•The combination of structural MRI and neurophysiological techniques could improve the understanding of CI in MS.
Event-related potentials (ERPs) have been proposed as a neurophysiological biomarker to capture cognitive dysfunction in multiple sclerosis (MS). Few studies have evaluated the relationships between ERPs and brain atrophy as known marker of structural brain damage related to cognitive impairment (CI).
To explore the relationships of brain atrophy, including of the cortex and deep grey matter, with ERP abnormalities and cognitive function, as defined using the Brief Repeatable Battery of Neuropsychological Tests (BRBN).
Seventy-eight patients with relapsing-remitting MS were enroled, of which 38 (48.7%) had CI. Independent t-test comparisons of the ERP parameters found a significant difference in P300 wave latency, with a latency of 343.7 ± 32.6 ms in the CI group vs. 320.3 ± 16.5 ms in the cognitively preserved (CP) group (p = 0.001). Significant differences in the MRI measurements, including the cortex (p = 0.02) and deep grey matter structures thalamus (p = 0.001), amygdala (p = 0.030), and nucleus accumbens (p = 0.004)) were observed, with lower measurements in the CI group. Regression models were also performed to explore the impact of brain volumes on ERP parameters. This showed a relationship between P300 latency and the lower amygdala (p = 0.02) and hippocampus (p = 0.03) volumes, while the amplitude of the P300 was significantly associated with a lower cortex volume (p = 0.01).
Cortex volume emerged as the most significant predictor of the P300 amplitude. The amygdala and hippocampal volumes were found to influence P300 latency, highlighting the role of deep grey matter atrophy in ERPs for the first time. The combination of structural MRI and neurophysiological techniques, sensitive to diverse aspects of MS pathology, could improve the understanding of CI in MS and its neurodegenerative and inflammatory substrate.
Autonomic and electroencephalographic (EEG) responses to aversive stimuli presented by means of hypnotic suggestion have been studied in man.
Healthy volunteers with simple phobia were screened for ...susceptibility to hypnosis. The experimental paradigm included periods of rest during which the hypnotized subjects were asked to produce an emotionally neutral mental image and periods of emotional activation in which they were asked to image a phobic object. Heart rate (HR), respiratory frequency (RF) and EEG were processed to obtain the HR-related indexes of sympatho-vagal balance and the EEG spectral components.
The results showed a significant increase in HR and RF with a shift of the sympatho-vagal indexes towards a sympathetic predominance during the hypnotic emotional activation. EEG activity showed a significant increase in the gamma band with a left fronto-central prevalence. There was also a less pronounced increase in the beta band.
In conclusion, by means of hypnosis, autonomic and behavioral responses to fear-like stimuli can be induced in man in a reproducible and controlled manner. Such a paradigm could be applied in human neuroimaging studies to identify central nervous structures that modulate stress and fear-related reactions.
Statistical parametric maps (SPMs) were computed using three different filter models, wherein either the free or the standard hemodynamic response functions (HRF) were used in combination with the ...full spectral bandwidth of the EEG.
This study highlights the application of recurrence quantification analysis (RQA) to derive information about nonlinear properties of heart rate variability (HRV). Parameters introduced by RQA, based ...on distance, recurrence and entropy of Recurrence Plots (RPs), show a natural application to cardiovascular signals, as descriptors of variable inherent complexity and determinism in different physiological conditions. RQA was applied to RR interval series collected in healthy subjects during relaxation, providing quantitative markers associated with the presence of complexity and determination in HRV.
Deals with the application of nonlinear analysis to the identification of spatially complex patterns in echographic images of normal and pathological carotid arteries. Complexity measures and indices ...are evaluated in normal and atherosclerotic plaques, related to the slow space-temporal evolution of biological patterns. In particular, we have found that the correlation dimension index lets one differentiate normal from pathological groups, allowing one to infer the complex interaction mechanism which is responsible for the plaque formation process.
Bevacizumab is approved in combination with chemotherapy for the treatment of ovarian cancer, either in first-line therapy or for patients with recurrent disease not previously treated with the same ...drug. We aimed to test the value of continuing bevacizumab beyond progression after first-line treatment with the same drug.
In our open-label, randomised, phase 3 trial done at 82 sites in four countries, we enrolled women (aged ≥18 years) who had previously received first-line platinum-based therapy including bevacizumab, and had recurrent (≥6 months since last platinum dose), International Federation of Gynaecology and Obstetrics stage IIIB–IV ovarian cancer with an Eastern Cooperative Oncology Group performance status 0–2. Patients were randomly assigned (1:1) to receive a carboplatin-based doublet intravenously (carboplatin area under the concentration curve AUC 5 on day 1 plus paclitaxel 175 mg/m2 on day 1, every 21 days; carboplatin AUC 4 on day 1 plus gemcitabine 1000 mg/m2 on days 1 and 8, every 21 days; or carboplatin AUC 5 on day 1 plus pegylated liposomal doxorubicin 30 mg/m2 on day 1, every 28 days), or a carboplatin-based doublet plus bevacizumab (10 mg/kg intravenous every 14 days combined with pegylated liposomal doxorubicin–carboplatin, or 15 mg/kg every 21 days combined with gemcitabine–carboplatin or paclitaxel–carboplatin). Evaluable disease according to RECIST 1.1 guidelines was required before randomisation. Randomisation was done through the trial website with a minimisation procedure, stratified by centre, time of recurrence, performance status, and type of second-line chemotherapy. The primary endpoint was investigator-assessed progression-free survival, analysed on an intention-to-treat basis. Safety was assessed in all participants who received at least one dose. This trial is registered with ClinicalTrials.gov, NCT01802749 and EudraCT 2012-004362-17.
Between Dec 6, 2013, and Nov 11, 2016, 406 patients were recruited (203 50% assigned to the bevacizumab group and 203 50% to the standard chemotherapy group). 130 patients (64%) in the bevacizumab group and 131 (65%) in the standard chemotherapy group had progressed after receiving a last dose of platinum more than 12 months before, and 146 patients (72%) in the bevacizumab group and 147 (72%) in the standard chemotherapy group had progressed after completion of first-line bevacizumab maintenance. 161 participants (79%) progressed in the standard chemotherapy group, as did 143 (70%) in the bevacizumab group. Median progression-free survival was 8·8 months (95% CI 8·4–9·3) in the standard chemotherapy group and 11·8 months (10·8–12·9) in the bevacizumab group (hazard ratio 0·51, 95% CI 0·41–0·65; log-rank p<0·0001). Most common grade 3–4 adverse events were hypertension (20 10% in the standard chemotherapy group vs 58 (29%) in the bevacizumab group), neutrophil count decrease (81 41% vs 80 40%), and platelet count decrease (43 22% vs 61 30%). 68 patients (33%) died in the standard chemotherapy group and 79 (39%) died in the bevacizumab group; two deaths (1%) in the standard chemotherapy group and one death (<1%) in the bevacizumab group were deemed to be treatment-related.
Continuing bevacizumab beyond progression combined with chemotherapy in patients with platinum-sensitive recurrent ovarian cancer improves progression-free survival compared with standard chemotherapy alone and might be considered in clinical practice.
Hoffmann–La Roche and Associazione Italiana per la Ricerca sul Cancro.
