Angelo Gemignani

Possible involvement of primary motor cortex in mentally simulated movement: a functional magnetic resonance imaging study

The role of the primary motor cortex (M1) during mental simulation of movement is open to debate. In the present study, functional magnetic resonance imaging (fMRI) signals were measured in normal right-handed subjects during actual and mental execution of a finger-to-thumb opposition task with either the right or the left hand. There were no significant differences between the two hands with either execution or simulation. A significant involvement of contralateral M1 (30% of the activity found during execution) was detected in four of six subjects. Premotor cortex (PM) and the rostral part of the posterior SMA were activated bilaterally during motor imagery. These findings support the hypothesis that motor imagery involves virtually all stages of motor control.

Performance evaluation of sensing fabrics for monitoring physiological and biomechanical variables

In the last few years, the smart textile area has become increasingly widespread, leading to developments in new wearable sensing systems. Truly wearable instrumented garments capable of recording behavioral and vital signals are crucial for several fields of application. Here we report on results of a careful characterization of the performance of innovative fabric sensors and electrodes able to acquire vital biomechanical and physiological signals, respectively. The sensing function of the fabric sensors relies upon newly developed strain sensors, based on rubber-carbon-coated threads, and mainly depends on the weaving topology, and the composition and deposition process of the conducting rubber-carbon mixture. Fabric sensors are used to acquire the respitrace (RT) and movement sensors (MS). Sensing features of electrodes, instead rely upon metal-based conductive threads, which are instrumental in detecting bioelectrical signals, such as electrocardiogram (ECG) and electromyogram (EMG). Fabric sensors have been tested during some specific tasks of breathing and movement activity, and results have been compared with the responses of a commercial piezoelectric sensor and an electrogoniometer, respectively. The performance of fabric electrodes has been investigated and compared with standard clinical electrodes.

Deriving the respiratory sinus arrhythmia from the heartbeat time series using Empirical mode decomposition

Abstract Heart rate variability (HRV) is a well-known phenomenon whose characteristics are of great clinical relevance in pathophysiologic investigations. In particular, respiration is a powerful modulator of HRV contributing to the oscillations at highest frequency. Like almost all natural phenomena, HRV is the result of many nonlinearly interacting processes; therefore any linear analysis has the potential risk of underestimating, or even missing, a great amount of information content. Recently the technique of empirical mode decomposition (EMD) has been proposed as a new tool for the analysis of nonlinear and nonstationary data. We applied EMD analysis to decompose the heartbeat intervals series, derived from one electrocardiographic (ECG) signal of 13 subjects, into their components in order to identify the modes associated with breathing. After each decomposition the mode showing the highest frequency and the corresponding respiratory signal were Hilbert transformed and the instantaneous phases extracted were then compared. The results obtained indicate a synchronization of order 1:1 between the two series proving the existence of phase and frequency coupling between the component associated with breathing and the respiratory signal itself in all subjects.

Depression and systemic lupus erythematosus: a systematic review

Objective Systemic lupus erythematosus (SLE) is a chronic, relapsing–remitting autoimmune disorder that involves multiple organ systems including the central nervous system. Among the items included in the nomenclature for neuropsychiatric SLE, mood disorders have been identified. The aim of this paper is to review the clinical and psychobiological relationship between depression and SLE. Method We performed a systematic search of MEDLINE, EMBASE, PsychINFO, using MeSH headings and keywords for ‘depression’ and ‘SLE’. Results Seventeen studies reported depressive disorders, with prevalence rates in the range 17–75%. Three studies reported the most frequent symptoms, which may be represented by fatigue, weakness, somatic disorders and sleep disorders. Suicide ideation was much higher than in the general population. Nine studies analysed the relationship to SLE disease activity. The results of the available literature are contradictory. Psychobiological hypotheses have been considered in 13 studies. Among the psychobiological hypotheses which might underline the plausibility of their relationship, ‘psychosocial factors’ were the most frequently reported. Conclusions Differences in assessment techniques appear to be the main explanation for the variability in findings and important methodological limitations are present in the available literature to definitively point to the prevalence of depression, type of depression and most prevalent symptoms. To date, the relationship between depression and SLE disease activity also appears controversial. Methodological limitations are present in the available literature and it would be necessary to develop evidence-based guidelines to improve the diagnosis of depression in SLE. Identification of SLE-specific biomarkers of depression also has high priority.

The dynamics of EEG gamma responses to unpleasant visual stimuli: from local activity to functional connectivity.

Many electroencephalographic (EEG) studies on the cortical dynamics induced by unpleasant picture viewing demonstrated the modulation of event-related potentials (ERPs) components as a function of valence and the increase of gamma band responses to emotional stimuli; while only a few studies investigated phase synchronization phenomena such as inter-trial or between regions phase locking of gamma responses to emotional stimulation. The aim of this study was to provide a complete description of the cortical dynamics induced by unpleasant and neutral pictures viewing, from the ERP averages to gamma rhythm modulation, and its phase synchronization. Gamma rhythm modulation was estimated by the event-related synchronization (ERS) approach, and phase synchrony between trials and between cortical regions was studied by extending the phase-locking statistics (PLS) approach. Consistent with previous literature, an increase in P300 and late positive potential and an increase in gamma activity during viewing of unpleasant pictures as compared to neutral ones were found. No inter-trial synchronization was evoked by the stimuli, whereas widespread phase locking between sites was identified. In particular, differences in gamma synchronization between unpleasant and neutral stimuli were found. Specifically, at early (0-250 ms) lags from stimulus onset, in the 38-45 Hz gamma interval, stronger inter-site synchronizations for the unpleasant stimuli, even though quite widespread across the scalp, mainly involved the interhemispheric synchronization between temporal and frontal regions. In contrast, in the 30-37 Hz gamma interval, stronger synchronizations for the responses to neutral trials were found in the 500-750 time interval, mainly involving the temporo-parietal regions. These findings suggest that the full elaboration of unpleasant stimuli requires a tight interhemispheric communication between temporal and frontal regions that is realized by means of phase synchronization at about 40 Hz. In addition, in contrast with the idea of a broadband modulation of high-frequency activity by cognitive/emotional stimuli, the present findings i.e. stronger BRS responses to either emotional or neutral trials at specific frequency and time range, indicate that specific intervals of gamma activity could be each primarily involved in a specific aspect of stimulus processing.

Poor sleep quality and resistant hypertension

OBJECTIVES We aimed to determine the relationship between sleep quality and treatment-resistant hypertension (RH). METHODS In our cross-sectional cohort study, 270 consecutive essential hypertensive patients were recruited at the Outpatient Hypertension Unit, University of Pisa, Italy. The Pittsburgh Sleep Quality Index (PSQI), Beck Depression Inventory (BDI), and State-Trait Anxiety Inventory (STAI-Y2) were administered to all subjects. RH was defined as office blood pressure (BP) >140/90 mmHg with three or more antihypertensive drugs or controlled BP with four or more drugs. Poor sleep quality was defined as PSQI >5, depressive symptoms as BDI >10, and trait anxiety as STAI-Y2 >40. Patients with other sleep disorders were excluded. RESULTS Complete data were available for 222 patients (50.9% men; mean age, 56.6±12.5 y; RH, 14.9%). Poor sleep quality had a prevalence of 38.2% in the overall population. RH was associated with poor sleep quality, increased sleep latency and reduced sleep efficiency. No significant relationship was found between RH and short sleep duration or depressive symptoms and trait anxiety. Poor sleep quality was more prevalent in resistant vs nonresistant hypertensive women (70.6% vs 40.2%; P=.02) but not in resistant vs nonresistant men (43.8% vs 29.2%; P=.24). In women poor sleep quality was an independent predictor of RH, even after adjustment for cardiovascular and psychiatric comorbidities (odds ratio [OR], 5.3 [confidence interval {CI}, 1.1-27.6), explaining 4.7% of its variance. In men age, diabetes mellitus (DM), and obesity were the only variables associated with RH. CONCLUSIONS Poor sleep quality is significantly associated with resistance to treatment in hypertensive women, independent of cardiovascular and psychiatric confounders.

Fractal complexity in spontaneous EEG metastable-state transitions: new vistas on integrated neural dynamics

Resting-state EEG signals undergo rapid transition processes (RTPs) that glue otherwise stationary epochs. We study the fractal properties of RTPs in space and time, supporting the hypothesis that the brain works at a critical state. We discuss how the global intermittent dynamics of collective excitations is linked to mentation, namely non-constrained non-task-oriented mental activity.

Functional Structure of Spontaneous Sleep Slow Oscillation Activity in Humans

Background During non-rapid eye movement (NREM) sleep synchronous neural oscillations between neural silence (down state) and neural activity (up state) occur. Sleep Slow Oscillations (SSOs) events are their EEG correlates. Each event has an origin site and propagates sweeping the scalp. While recent findings suggest a SSO key role in memory consolidation processes, the structure and the propagation of individual SSO events, as well as their modulation by sleep stages and cortical areas have not been well characterized so far. Methodology/Principal Findings We detected SSO events in EEG recordings and we defined and measured a set of features corresponding to both wave shapes and event propagations. We found that a typical SSO shape has a transition to down state, which is steeper than the following transition from down to up state. We show that during SWS SSOs are larger and more locally synchronized, but less likely to propagate across the cortex, compared to NREM stage 2. Also, the detection number of SSOs as well as their amplitudes and slopes, are greatest in the frontal regions. Although derived from a small sample, this characterization provides a preliminary reference about SSO activity in healthy subjects for 32-channel sleep recordings. Conclusions/Significance This work gives a quantitative picture of spontaneous SSO activity during NREM sleep: we unveil how SSO features are modulated by sleep stage, site of origin and detection location of the waves. Our measures on SSOs shape indicate that, as in animal models, onsets of silent states are more synchronized than those of neural firing. The differences between sleep stages could be related to the reduction of arousal system activity and to the breakdown of functional connectivity. The frontal SSO prevalence could be related to a greater homeostatic need of the heteromodal association cortices.

Autonomic and EEG correlates of emotional imagery in subjects with different hypnotic susceptibility

The autonomic and EEG correlates of the response to a cognitive unpleasant stimulation (US) verbally administered to awake hypnotizable and non hypnotizable subjects were studied. They were compared with the values obtained during a resting condition immediately preceding the stimulus and with those produced by a cognitive neutral stimulation (NS), also administered after a basal resting period. Results showed hypnotic trait effects on skin resistance, heart and respiratory rate as well as on EEG theta, alpha, beta and gamma relative power changes. The autonomic and EEG patterns observed indicated different strategies in the task execution for hypnotizable and non hypnotizable subjects and a discrepancy between the autonomic and EEG changes associated to the US in susceptible subjects. Results support dissociation theories of hypnosis and suggest for hypnotizable persons an active mechanism of protection against cardiac hazard.

Sleep-related improvements in motor learning following mental practice.

A wide range of experimental studies have provided evidence that a night of sleep may enhance motor performance following physical practice (PP), but little is known, however, about its effect after motor imagery (MI). Using an explicitly learned pointing task paradigm, thirty participants were assigned to one of three groups that differed in the training method (PP, MI, and control groups). The physical performance was measured before training (pre-test), as well as before (post-test 1) and after a night of sleep (post-test 2). The time taken to complete the pointing tasks, the number of errors and the kinematic trajectories were the dependent variables. As expected, both the PP and the MI groups improved their performance during the post-test 1. The MI group was further found to enhance motor performance after sleep, hence suggesting that sleep-related effects are effective following mental practice. Such findings highlight the reliability of MI in learning process, which is thought consolidated when associated with sleep.