Brunello Ghelarducci

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.

The action of steroid hormones on peripheral myelin proteins: A possible new tool for the rebuilding of myelin?

The present paper summarizes recent results we have obtained while studying the effect of sex steroids on the gene expression of two peripheral myelin proteins, the glycoprotein Po (Po) and the peripheral myelin protein 22 (PMP22). In particular, we have analyzed the effect of progesterone (P), testosterone (T) and their 5α- and 3α-5α-reduced derivatives [respectively, dihydrotestosterone (DHT) and 5α-androstan-3α, 17β-diol (3α-diol) for T, and dihydroprogesterone (DHP) and tetrahydroprogesterone (THP) for P]. The data obtained, utilizing different in vivo and in vitro experimental models, have indicated that: a) DHP is able to enhance the low messenger levels of Po present in the sciatic nerve of aged male rats; b) P, DHP and THP treatments stimulate the gene expression of Po in the sciatic nerve of adult male rats or in cultures of rat Schwann cells, while only THP is effective on PMP22; c) P and DHP are also able to increase the low messenger levels of Po present in transected sciatic nerve; d) the removal of circulating androgens by castration is able to decrease the mRNA levels of Po in the sciatic nerve, a phenomenon which is counteracted by the consequent treatment with DHT; e) the stimulatory effect of DHT on the gene expression of Po is also evident in cultures of rat Schwann cells, but in this case the effect seems to be due to the interaction of this steroid with the progesterone receptor; f) in cultures of Schwann cells PMP22 mRNA levels are stimulated only by 3α-diol treatment. Taken together, these observations showing the positive effects of sex steroid hormones on the gene expressions of Po and PMP22, suggest that a treatment with these molecules or their synthetic agonists may be useful in cases in which the rebuilding of myelin is necessary.

The role of the posterior cerebellar vermis in cardiovascular control

The effects of electrical stimulation of the posterior cerebellar vermis in anaesthetized, decerebrate and conscious animals are described, and include marked changes in blood pressure and heart rate and an inhibition of the baroreceptor reflex. These effects appear to be restricted to lobule IX, and can be duplicated by chemical stimulation, indicating that they are a genuine cerebellar phenomenon. The results of both neuroanatomical and neurophysiological experiments to investigate the pathways responsible for the effects are described, and these show there to be a direct projection of Purkinje cell axons to the parabrachial nucleus. Experiments designed to test a possible involvement of lobule IX in the alerting response have proved negative, and while lobule IX itself appears to have no role in conditioned cardiovascular responses, lesions of lobules VI and VII do result in a significant impairment of the acquisition of conditioned bradycardia in the rabbit.

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.

Does hypnotizability modulate the stress-related endothelial dysfunction?

Previous studies suggest that hypnotizability represents a protective factor against the cardiac effects of cognitive stress and that hypnosis prevents vascular stress-induced modifications in highly hypnotizable individuals. The aim of the experiment was to investigate whether a similar effect at vascular level is present in awake subjects with a high (Highs) and a low (Lows) hypnotic susceptibility. Thus, brachial artery post-ischaemic flow-mediated vascular dilation (FMD) was evaluated non-invasively by ultrasound methodology during cognitive stress (mental computation) in Highs and Lows. Results showed that Highs, similarly to that previously observed in hypnotized Highs and in contrast with Lows, did not exhibit any stress-related endothelial dysfunction (FMD decrement). Thus, hypnotizability should be considered a protective factor against vascular disease.

Changes in autonomic and EEG patterns induced by hypnotic imagination of aversive stimuli in man

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.

Efferent connections of lobule IX of the posterior cerebellar cortex in the rabbit — some functional considerations

The Purkinje cell projection from the cardiovascular region of sublobule b of the uvula (medial area of zone A) has been investigated using anterograde tracing methods in the rabbit. The importance of the integrity of the identified pathways in mediating the cardiovascular responses from the uvula has been studied in subsequent lesioning experiments. Wheat germ agglutinin-conjugated horseradish peroxidase or tritiated amino acids were microinjected into sublobule IXb. This resulted in anterogradely labelled Purkinje cell axons in both the inferior and superior cerebellar peduncle. In agreement with previous studies in rabbit we also found labelled fibres at the level of the fastigial nucleus and vestibular complex. However, the labelled fibres we observed in the parabrachial nucleus have not been reported in previous studies except in the prosimian primate. Projections from IXb showed terminal-like patterns of label in the ventromedial region of the caudal fastigial nucleus, the dorsal areas of the superior and inferior vestibular nuclei and in the medial and lateral divisions of the parabrachial nucleus. Labelled fibres were also seen coursing in the lateral vestibular nucleus. Lesioning experiments have revealed that the integrity of the superior cerebellar peduncle is essential for the expression of the cardiovascular responses (bradycardia and depressor response) elicited from the uvula in the anaesthetized rabbit. In contrast, the pattern of cardiovascular response evoked in a decerebrate rabbit (tachycardia and pressor response) was abolished when the inferior cerebellar peduncle was lesioned.

Influence of the cerebellar posterior vermis on the acquisition of the classically conditioned bradycardic response in the rabbit.

SummaryThe magnitude of classically conditioned bradycardia was studied in rabbits in which various cerebellar regions (lobule IX or the posterior vermis or the hemispheres) had been removed surgically. Lesions were shown histologically to be restricted to the cortex and the underlying white matter without any damage to the deep cerebellar nuclei. In the conditioning procedure, tones were employed as conditioned stimuli (CS) and ear shocks as unconditioned stimuli (US). Cerebellar lesions did not affect the characteristics of the bradycardic orienting response, baseline heart rate or the unconditioned tachycardic response to US. The conditioned bradycardia was significantly reduced in magnitude with respect to controls in rabbits submitted to removal of posterior vermis, while it was unaffected in lobule IX and hemispheric lesioned rabbits. The temporal pattern of development and habituation of the bradycardic response through the conditioning session, as well as its topography, did not differ from controls in any of the lesioned rabbits. After the first conditioning session, some control rabbits were submitted to removal of the posterior vermis and then conditioned again, following an identical procedure. Their pre- and post-lesion conditioned responses did not exhibit any appreciable differences and were similar to the responses exhibited by a group of unoperated controls which were submitted to a reconditioning session. It is concluded that in the rabbit the cerebellar posterior vermis is involved in the initial acquisition of the classically conditioned bradycardia, but it is not the site of its memory trace.

Effects of vestibular and neck proprioceptive stimulation on posture as a function of hypnotizability.

Abstract Previous studies on the role of hypnotizability in postural control indicate that the body sway of subjects with high or low hypnotizability to hypnosis is differentially modulated by eye closure. The aim of this study was to investigate whether hypnotizability also modulates the postural response to electrical vestibular stimulation and to head rotation in nonhypnotized individuals. The center of pressure (CoP) displacements were monitored in highs and lows standing on a stabilometric platform with closed eyes during basal conditions and electrical vestibular stimulation in 3 different positions of the head. Results showed that the CoP stimulus-locked displacements as well as the CoP mean position, area, and mean velocity were similar in highs and lows, but only in lows did the head position modulate the mean velocity. This finding might reflect a difference in sensory-motor integration between the 2 groups.