Internal Representations of Temporal Statistics and Feedback Calibrate Motor-Sensory Interval Timing

Humans have been shown to adapt to the temporal statistics of timing tasks so as to optimize the accuracy of their responses, in agreement with the predictions of Bayesian integration. This suggests that they build an internal representation of both the experimentally imposed distribution of time intervals (the prior) and of the error (the loss function). The responses of a Bayesian ideal observer depend crucially on these internal representations, which have only been previously studied for simple distributions. To study the nature of these representations we asked subjects to reproduce time intervals drawn from underlying temporal distributions of varying complexity, from uniform to highly skewed or bimodal while also varying the error mapping that determined the performance feedback. Interval reproduction times were affected by both the distribution and feedback, in good agreement with a performance-optimizing Bayesian observer and actor model. Bayesian model comparison highlighted that subjects were integrating the provided feedback and represented the experimental distribution with a smoothed approximation. A nonparametric reconstruction of the subjective priors from the data shows that they are generally in agreement with the true distributions up to third-order moments, but with systematically heavier tails. In particular, higher-order statistical features (kurtosis, multimodality) seem much harder to acquire. Our findings suggest that humans have only minor constraints on learning lower-order statistical properties of unimodal (including peaked and skewed) distributions of time intervals under the guidance of corrective feedback, and that their behavior is well explained by Bayesian decision theory.     

A Novel Algorithm for Movement Artifact Removal in ECG Signals Acquired from Wearable Systems Applied to Horses

This study reports on a novel method to detect and reduce the contribution of movement artifact (MA) in electrocardiogram (ECG) recordings gathered from horses in free movement conditions. We propose a model that integrates cardiovascular and movement information to estimate the MA contribution. Specifically, ECG and physical activity are continuously acquired from seven horses through a wearable system. Such a system employs completely integrated textile electrodes to monitor ECG and is also equipped with a triaxial accelerometer for movement monitoring. In the literature, the most used technique to remove movement artifacts, when noise bandwidth overlaps the primary source bandwidth, is the adaptive filter. In this study we propose a new algorithm, hereinafter called Stationary Wavelet Movement Artifact Reduction (SWMAR), where the Stationary Wavelet Transform (SWT) decomposition algorithm is employed to identify and remove movement artifacts from ECG signals in horses. A comparative analysis with the Normalized Least Mean Square Adaptive Filter technique (NLMSAF) is performed as well. Results achieved on seven hours of recordings showed a reduction greater than 40% of MA percentage (between before- and after- the application of the proposed algorithm). Moreover, the comparative analysis with the NLMSAF, applied to the same ECG recordings, showed a greater reduction of MA percentage in favour of SWMAR with a statistical significant difference (p–value < 0.0.5).     

Modulation of the cell-mediated immune function by interferon α, β or γ can partially reverse the immunosuppression induced by human T-cell leukemia virus I in human cord blood cultures

Summary Infection with human T-cell leukemia virus type I (HTLV-I) is associated in vitro and in vivo with a remarkable depression of cell-mediated immune functions. In the present report it is shown that early events following virus-induced suppression of the cell-mediated immune response of freshly isolated cord blood mononuclear cells (CBL) infected with HTLV-I can be partially counteracted by treatment with interferons , or (IFN). All three types of IFN exerted a protective effect on CBL cultures exposed to the virus. This resulted in: (a) a reduced number of virus-positive cells until 4 weeks of culture; (b) delay in the clonal expansion of infected cells (IFN and ); (c) increased natural killer cell activity of CBL, 1 week post-infection (p.i.), mediated by IFN; (d) increase of allospecific recognition of infecting and priming HTLV-I donor MT-2 cells by CBL in a cytotoxic-T-lymphocyte-like response, mediated by IFN and particularly by IFN; (e) phenotype distribution of CBL subpopulations, tested 4 days p.i., more similar to that of non-infected CBL cultures.In contrast, the overall CBL proliferation, that is profoundly depressed during the first week p.i., was not restored by IFN treatments, suggesting that boosting of the cell-mediated killing induced by IFN might involve the maturation of undifferentiated precursor cells rather than stimulation of their proliferation. The improvement of the efficiency of the antiviral immune response induced by treatment with IFN is likely to contribute to the clearance of virus-positive cells during the early phase of infection. This would provide experimental evidence to support an immunopharmacological approach contributing to the conversion of HTLV-I carriers from positive to negative.     

The presence of immunoreactive vertebrate bioactive peptide substances in hemocytes of the freshwater snailViviparus ater (gastropoda,prosobranchia)

1. Using an immunocytochemical procedure a wide range of immunoreactive vertebrate bioactive peptides (BAPs) has been found in hemocytes of Viviparus ater: bombesin, calcitonin, CCK-8, CCK-39, GH, glucagon, insulin, oxytocin, neurotensin, secretin, serotonin, somatostatin, substance P, vasopressin, and VIP. 2. No immunostaining was observed for antigastrin and antithyroglobulin antibodies. 3. The presence of BAP-like molecules in hemocytes suggests a correlation between hemocyte and APUD cells and is evidence of a relationship between the neuroendocrine and the immune systems.     

Studies on Analogues of Succinic Semialdehyde as Substrates for Succinate Semialdehyde Dehydrogenase from Rat Brain

The methyl ester of succinic semialdehyde (SSA) was examined as a substrate for succinate semialdehyde dehydrogenase (SSADH) from rat brain. It was found that the ester can be oxidized by the enzyme. Values of Km for SSA-Me were higher than for those for SSA, and for this substrate the enzyme showed a substrate-dependent inhibition. This finding suggests that the carboxylate group of SSA is not essential in the process of inhibition of SSADH by the substrate. Cyclopropyl analogues of SSA, cis- and trans-1-formyl-cyclopropan-2-carboxylic acids, were also individually tested as substrates of SSADH. Only the trans isomer was found to be oxidized to the corresponding dicarboxylic acid; it inhibited the enzyme in the same range of concentrations as SSA. The above data suggest that, as for gamma-aminobutyric acid, SSA is present in an unfolded, transoid conformation at the active site of SSADH.