Search results for "Autore"
showing 10 items of 352 documents
Testing Frequency-Domain Causality in Multivariate Time Series
2010
We introduce a new hypothesis-testing framework, based on surrogate data generation, to assess in the frequency domain, the concept of causality among multivariate (MV) time series. The approach extends the traditional Fourier transform (FT) method for generating surrogate data in a MV process and adapts it to the specific issue of causality. It generates causal FT (CFT) surrogates with FT modulus taken from the original series, and FT phase taken from a set of series with causal interactions set to zero over the direction of interest and preserved over all other directions. Two different zero-setting procedures, acting on the parameters of a MV autoregressive (MVAR) model fitted on the ori…
Time-Varying Surrogate Data to Assess Nonlinearity in Nonstationary Time Series: Application to Heart Rate Variability
2009
We propose a method to extend to time-varying (TV) systems the procedure for generating typical surrogate time series, in order to test the presence of nonlinear dynamics in potentially nonstationary signals. The method is based on fitting a TV autoregressive (AR) model to the original series and then regressing the model coefficients with random replacements of the model residuals to generate TV AR surrogate series. The proposed surrogate series were used in combination with a TV sample entropy (SE) discriminating statistic to assess nonlinearity in both simulated and experimental time series, in comparison with traditional time-invariant (TIV) surrogates combined with the TIV SE discrimin…
Modulation by 5-HT3 and 5-HT4 receptors of the release of 5-hydroxytryptamine from the guinea-pig small intestine.
1993
The effects of agonists and antagonists of 5-hydroxytryptamine (5-HT) receptors on the release of endogenous 5-HT from enterochromaffin cells were studied in the vascularly perfused isolated guinea-pig small intestine. The experiments were done in the presence of tetrodotoxin in order to exclude a neuronally mediated influence on 5-HT release. The 5-HT3 receptor agonist 2-methyl-5-HT increased 5-HT release, and this effect was antagonized by 1 nmol/l tropisetron. Nanomolar concentrations of tropisetron, MDL 72,222 and granisetron decreased 5-HT release. Ondansetron (0.1 and 1 mumol/l) did not modify 5-HT release. 5-Methoxytryptamine, BIMU8 and cisapride concentration-dependently inhibited 5…
Enhancement of the FGFR1 signaling in the FGFR1-5-HT1A heteroreceptor complex in midbrain raphe 5-HT neuron systems. Relevance for neuroplasticity an…
2015
New findings show existence of FGFR1-5-HT1A heteroreceptor complexes in 5-HT nerve cells of the dorsal and median raphe nuclei of the rat midbrain and hippocampus. Synergistic receptor-receptor interactions in these receptor complexes indicated their enhancing role in hippocampal plasticity. The existence of FGFR1-5-HT1A heteroreceptor complexes also in midbrain raphe 5-HT nerve cells open up the possibility that antidepressant drugs by increasing extracellular 5-HT levels can cause an activation of the FGF-2/FGFR1 mechanism in these nerve cells as well. Therefore, the agonist modulation of the FGFR1-5-HT1A heteroreceptor complexes and their specific role is now determined in rat medullary …
ATP and endogenous agonists inhibit evoked [3H]-noradrenaline release in rat iris via A1 and P2y-like purinoceptors.
1993
Effects of ATP, adenosine and purinoceptor antagonists on field stimulation-evoked (3 Hz, 2 min) [3H]-noradrenaline overflow were investigated in the rat isolated iris. ATP and adenosine inhibited the evoked overflow of [3H]-noradrenaline. 1,3-Dipropyl-8-cyclopentylxanthine (DPCPX) shifted the concentration-response curve of ATP to the right in a concentration-dependent manner, but with a potency (-log KB = 7.88) much lower than expected for an A1 adenosine receptor. In the continuous presence of DPCPX, the ATP-induced prejunctional inhibition was unaffected by suramin (100 mumol/l) and DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid, 50 mumol/l) but was antagonized by the P2Y-rece…
Roxindole, a dopamine autoreceptor agonist, in the treatment of positive and negative schizophrenic symptoms
1994
Twenty schizophrenic inpatients with either predominantly positive or predominantly negative symptoms were treated with the dopamine autoreceptor agonist roxindole in prospective open clinical trials. There was no antipsychotic effect in the subgroup with positive symptoms, whereas the subgroup with negative symptoms, especially those with the residual type of schizophrenia, showed a moderate but significant 20% reduction in total scores on the Scale for the Assessment of Negative Symptoms.
Desensitization of inhibitory prejunctional alpha 2-adrenoceptors and putative imidazoline receptors on rabbit heart sympathetic nerves.
1993
To find out whether sympathetic nerves of the rabbit heart possess pharmacologically relevant prejunctional imidazoline receptors different from α-autoreceptors, the inhibition by oxymetazoline, aganodine and BDF 6143 (4-chloro-2-[2-imidazoline-2-ylamino]-isoindoline hydrochloride) of endogenous noradrenaline overflow evoked by stimulation of extrinsic postganglionic sympathetic nerves (0.66 Hz, 80 pulses) was investigated. In addition we wanted to find out whether either type of these prejunctional receptors undergoes desensitization upon pre-exposure to respective agonists. The α2-adrenoceptor agonist oxymetazoline inhibited the evoked noradrenaline overflow (2.9 nmol/l, IC50; about 90010…
Increase of the FGFR1 signaling in the FGFR1-5-HT1A heteroreceptor complex in midbrain raphe 5-HT neuron systems via allosteric receptor-receptor int…
2015
The ascending midbrain 5-HT neurons known to contain 5-HT1A autoreceptors may be dysregulated in depression due to a reduced trophic support. New findings show existence of FGFR1-5-HT1A heteroreceptor complexes in the rat hippocampus with a partial characterization of their interface and in midbrain raphe 5-HT nerve cells. With in situ Proximity Ligation Assay (PLA) and supported by co-location of the FGFR1 and 5-HT1A immunoreactivities in midbrain raphe 5-HT cells, evidence for the existence of FGFR1-5-HT1A heteroreceptor complexes were obtained in the dorsal and median raphe nuclei of the Sprague–Dawley rat. Their existence in the rat medullary raphe RN33B cell cultures was also establish…
Breve fenomenologia della vita emotiva nella prospettiva dell'educazione
2018
The paper explores the link between human becoming and biographical narrative, within the empathy-centred existential dialogue. The existential dialogue should not be assimilated to a psychotherapeutic method: it is, rather, a special care relationship within an educational perspective. In a semiological analysis, the existential dialogue is an interaction shaped according to an empathetic code and giving rise to a peculiar relational regulation system based on: 1. demandingness (or control), linked to authority and competence; 2. emotional responsiveness (or empathetic contact), linked to socio-affective interaction; 3. authenticity (or congruence), linked to transparency in speaking. In a…
Estimation of Granger causality through Artificial Neural Networks: applications to physiological systems and chaotic electronic oscillators
2021
One of the most challenging problems in the study of complex dynamical systems is to find the statistical interdependencies among the system components. Granger causality (GC) represents one of the most employed approaches, based on modeling the system dynamics with a linear vector autoregressive (VAR) model and on evaluating the information flow between two processes in terms of prediction error variances. In its most advanced setting, GC analysis is performed through a state-space (SS) representation of the VAR model that allows to compute both conditional and unconditional forms of GC by solving only one regression problem. While this problem is typically solved through Ordinary Least Sq…