Two attentive strategies reducing subjective distortions in serial duration perception

Humans tend to perceptually distort (dilate/shrink) the duration of brief stimuli presented in a sequence when discriminating the duration of a second stimulus (Comparison) from the duration of a first stimulus (Standard). This type of distortion, termed “Time order error” (TOE), is an important window into the determinants of subjective perception. We hypothesized that stimulus durations would be optimally processed, suppressing subjective distortions in serial perception, if the events to be compared fell within the boundaries of rhythmic attentive sampling (4–8 Hz, theta band). We used a two-interval forced choice (2IFC) experimental design, and in three separate experiments tested different Standard durations: 120-ms, corresponding to an 8.33 Hz rhythmic attentive window; 160 ms, corresponding to a 6.25 Hz window; and 200 ms, for a 5 Hz window. We found that TOE, as measured by the Constant Error metric, is sizeable for a 120-ms Standard, is reduced for a 160-ms Standard, and statistically disappears for 200-ms Standard events, confirming our hypothesis. For 120- and 160-ms Standard events, to reduce TOEs it was necessary to increase the interval between the Standard and the Comparison event from sub-second (400, 800 ms) to supra-second (1600, 2000 ms) lags, suggesting that the orienting of attention in time waiting for the Comparison event to onset may work as a back-up strategy to optimize its encoding. Our results highlight the flexible use of two different attentive strategies to optimize subjective time perception

Neural entrainment via perceptual inferences

Entrainment depends on sequential neural phase reset by regular stimulus onset, a temporal parameter. Entraining to sequences of identical stimuli also entails stimulus feature predictability, but this component is not readily separable from temporal regularity. To test if spectral regularities concur with temporal regularities in determining the strength of auditory entrainment, we devised sound sequences that varied in conditional perceptual inferences based on deviant sound repetition probability: strong inference (100% repetition probability: If a deviant appears, then it will repeat), weak inference (75% repetition probability) and no inference (50%: A deviant may or may not repeat with equal probability). We recorded EEG data from 15 young human participants pre-attentively listening to the experimental sound sequences delivered either isochronously or anisochronously (±20% jitter), at both delta (1.67 Hz) and theta (6.67 Hz) stimulation rates. Strong perceptual inferences significantly enhanced entrainment at either stimulation rate and determined positive correlations between precision in phase distribution at the onset of deviant trials and entrained power. We conclude that both spectral predictability and temporal regularity govern entrainment via neural phase control

A perceptual glitch in serial perception generates temporal distortions

Precisely estimating event timing is essential for survival, yet temporal distortions are ubiquitous in our daily sensory experience. Here, we tested whether the relative position, duration, and distance in time of two sequentially-organized events—standard S, with constant duration, and comparison C, with duration varying trial-by-trial—are causal factors in generating temporal distortions. We found that temporal distortions emerge when the first event is shorter than the second event. Importantly, a significant interaction suggests that a longer inter-stimulus interval (ISI) helps to counteract such serial distortion effect only when the constant S is in the first position, but not if the unpredictable C is in the first position. These results imply the existence of a perceptual bias in perceiving ordered event durations, mechanistically contributing to distortion in time perception. We simulated our behavioral results with a Bayesian model and replicated the finding that participants disproportionately expand first-position dynamic (unpredictable) short events. Our results clarify the mechanisms generating time distortions by identifying a hitherto unknown duration-dependent encoding inefficiency in human serial temporal perception, something akin to a strong prior that can be overridden for highly predictable sensory events but unfolds for unpredictable ones

Effect of Immunoglobin-Like Transcript 7 Cross-Linking on Plasmacytoid Dendritic Cells Differentiation into Antigen-Presenting Cells

Plasmacytoid dendritic cells (pDC) are innate immunity effector cells which play a critical role in the transition from innate to adaptive immune response. Circulating blood pDC present an immature phenotype and can differentiate into either antigen-presenting cells (APC) or type I interferon (IFN-I)-producing cells (IPC). The immunoglobulin-like transcript (ILT)7 is a surface receptor expressed by immature pDC, and ILT7 cross-linking (XL-ILT7) inhibits IFN-I production by pDC in response to toll-like receptor (TLR)7 and 9 stimulation. We used peripheral blood mononuclear cells (PBMC) from healthy donors to test the effect of XL-ILT7 on 1) TLR7/9-mediated regulation of gut mucosal (α4β7 integrin) and lymph node (CCR7) migration markers; and 2) the maturation of pDC into APC. We found that XL-ILT7 mitigated the upregulation of CCR7 and enhanced that of β7 on TLR7/9-stimulated pDC. TLR7/9 stimulation induced upregulation of CD40, CD80 and CD86. CD40 expression was partially reduced by XL-ILT7, whereas CD86 was further enhanced. Plasmacytoid DC stimulated with TLR9 ligand in presence of XL-ILT7 retained the ability to induce T cell proliferation and activation in response to staphylococcal enterotoxin B (SEB) in pDC-T cell co-cultures. Our results suggest that XL-ILT7 favours the differentiation of immature pDC into APC rather than IPC

Auditory dialog analysis and understanding by generative modelling of interactional dynamics

In the last few years, the interest in the analysis of human behavioral schemes has dramatically grown, in particular for the interpretation of the communication modalities called social signals. They represent well defined interaction patterns, possibly unconscious, characterizing different conversational situations and behaviors in general. In this paper, we illustrate an automatic system based on a generative structure able to analyze conversational scenarios. The generative model is composed by integrating a Gaussian mixture model and the (observed) influence model, and it is fed with a novel kind of simple low-level auditory social signals, which are termed steady conversational periods (SCPs). These are built on duration of continuous slots of silence or speech, taking also into account conversational turn-taking. The interactional dynamics built upon the transitions among SCPs provide a behavioral blueprint of conversational settings without relying on segmental or continuous phonetic features. Our contribution here is to show the effectiveness of our model when applied on dialogs classification and clustering tasks, considering dialogs between adults and between children and adults, in both flat and arguing discussions, and showing excellent performances also in comparison with state-of-the-art frameworks

Prosody abilities in a large sample of affective and non-affective first episode psychosis patients

Objective: Prosody comprehension deficits have been reported in major psychoses. It is still not clear whether these deficits occur at early psychosis stages. The aims of our study were to investigate a) linguistic and emotional prosody comprehension abilities in First Episode Psychosis (FEP) patients compared to healthy controls (HC); b) performance differences between non-affective (FEP-NA) and affective (FEP-A) patients, and c) association between symptoms severity and prosodic features. Methods: A total of 208 FEP (156 FEP-NA and 52 FEP-A) patients and 77 HC were enrolled and assessed with the Italian version of the “Protocole Montréal d'Evaluation de la Communication” to evaluate linguistic and emotional prosody comprehension. Clinical variables were assessed with a comprehensive set of standardized measures. Results: FEP patients displayed significant linguistic and emotional prosody deficits compared to HC, with FEP-NA showing greater impairment than FEP-A. Also, significant correlations between symptom severity and prosodic features in FEP patients were found. Conclusions: Our results suggest that prosodic impairments occur at the onset of psychosis being more prominent in FEP-NA and in those with severe psychopathology. These findings further support the hypothesis that aprosodia is a core feature of psychosis

Isolation and pathogenicity of Xylella fastidiosa associated to the olive quick decline syndrome in southern Italy

In autumn 2013, the presence of Xylella fastidiosa, a xylem-limited Gram-negative bacterium, was detected in olive stands of an area of the Ionian coast of the Salento peninsula (Apulia, southern Italy), that were severely affected by a disease denoted olive quick decline syndrome (OQDS). Studies were carried out for determining the involvement of this bacterium in the genesis of OQDS and of the leaf scorching shown by a number of naturally infected plants other than olive. Isolation in axenic culture was attempted and assays were carried out for determining its pathogenicity to olive, oleander and myrtle-leaf milkwort. The bacterium was readily detected by quantitative polymerase chain reaction (qPCR) in all diseased olive trees sampled in different and geographically separated infection foci, and culturing of 51 isolates, each from a distinct OQDS focus, was accomplished. Needle-inoculation experiments under different environmental conditions proved that the Salentinian isolate De Donno belonging to the subspecies pauca is able to multiply and systemically invade artificially inoculated hosts, reproducing symptoms observed in the field. Bacterial colonization occurred in prick-inoculated olives of all tested cultivars. However, the severity of and timing of symptoms appearance differed with the cultivar, confirming their differential reaction