86,526 research outputs found
Auto-Associative Recurrent Neural Networks and Long Term Dependencies in Novelty Detection for Audio Surveillance Applications
No full textMachine Learning applied to Automatic Audio Surveillance has been attracting increasing attention in recent years. In spite of several investigations based on a large number of different approaches, little attention had been paid to the environmental temporal evolution of the input signal. In this work, we propose an exploration in this direction comparing the temporal correlations extracted at the feature level with the one learned by a representational structure. To this aim we analysed the prediction performances of a Recurrent Neural Network architecture varying the length of the processed input sequence and the size of the time window used in the feature extraction. Results corroborated the hypothesis that sequential models work better when dealing with data characterized by temporal order. However, so far the optimization of the temporal dimension remains an open issu
Striatal dynamics as determinants of reduced gambling vulnerability in the NHE rat model of ADHD
No full textThe Naples High-Excitability (NHE) is a validated rat strain to model for a mesocortical variant of Attention Deficit Hyperactivity Disorder (ADHD). NHE rats' brains have a tuned-down cortical and a potentiated limbic loop (Zoratto et al., 2017). ADHD and comorbid pathological gambling (PG) involve similar deficits of prefrontal-striatal dialogue. This work aimed to understand if NHE rats (compared to normal random-bred rats, NRB) can be a useful model for gambling vulnerability in ADHD. Experiment 1 evaluated gambling proneness in NHE rats, namely attraction/avoidance in nose-poking for a “Large & Luck-Linked” (LLL) reward (versus a “Small & Sure” one, SS), when the probability of LLL delivery was progressively reduced. Experiment 2 assessed (by phMRI) differential responsivity of ventral (vStr) versus dorsal (dStr) striatum following a methylphenidate (MPH, 4 mg/kg I.P.) challenge. In NHE rats, reduced attraction by secondary cues (associated with uncertain, rarefying LLL delivery) comes along with little or no activation of dStr and enhanced activation of vStr by MPH. Together, such evidences from NHE rats indicate distinctive roles of ventral (enhanced value given to actual primary reward) and dorsal (lower encoding of repeated stimulus-reward associations into a habit) striatum. In conclusion, the dynamics of reward systems could link an attention deficit with a decreased vulnerability to pathological gambling
The presence of a potential competitor modulates risk preferences in rats
No full textAlthough both human and non-human animals, in everyday life, deal with risky decisions in a social environment,
few studies investigated how social dimension influences risk preferences (i.e., if consequences on others
feeds back over own choice). Here, we assessed whether the presence of a conspecific, acting as a potential
competitor for the same food resource, influenced risky decision-making in male rats. Subjects received a series
of choices between a safe option (always yielding a small yet optimal reward, solely to itself) and a risky option
(yielding a larger but suboptimal reward, one third of times to itself and two third of times delivered to the other
half cage); rats were tested twice, both alone and paired with a conspecific, recipient of own-lost food and hence
acting as potential competitor. Results showed that focal subjects were more risk-prone when paired with a
conspecific than when tested alone. However, rats exhibited also a higher motivational conflict with a competing
bystander present than alone: data suggest that the primary drive was to increase "own" food rather than either a
competitive or prosocial tendency. Overall, for rats tested in a risky-choice task, a competitive social context
increased the salience and attractiveness of larger food outcomes, as observed in humans and great apes. This led
to the economically irrational response of selecting the “binge-but-risky” option, notwithstanding uncertainty
about the actual recipient of such food
A new paradigm for Prosocial Behavior and Reciprocity, assessed in WT and HET rats for the DAT gene
No full textMost behavioral studies on animals focus on observation of individual subjects. Current paradigms of sociability set aside the social-operant dimension, i.e. acting in favor of another conspecific. We focused on prosocial behavior and reciprocity of male, adult Wild-Type (WT) and Heterozygous (HET) rats for the dopamine-transporter (DAT) gene. Method: The experiment consisted of 24 rats, of WT (n = 12) and HET (n = 12) genotypes. During training, rats were daily introduced, individually, into an apparatus hosting a suspended syringe, which they learnt to push in order to obtain food therein. Then, twice daily along several weeks, we introduced two rats separated by a grid in the same structure: by syringe-pushing, each subject had the opportunity to donate and receive donations of food. We tested pairs with similar versus different genotype. Eventually, we replaced food reward with polystyrene pieces, to understand if they pushed for actual reward or like a habit. Results: In general, WT rats had better performance, regardless of reward type, than HET ones. When we crossed partner rats’ genotype (WT-HET pairs), WT rats pushed at peak levels, regardless of food pellet received back (in fact, HET companions pushed less). Couples of WT rats achieved better results than HET ones even when polystyrene, instead of food, was used. Thus,WT rats seem to be a better model for altruistic behavior than HET ones. For this reason, HET rats could represent a model for studies on altered prosocial behavior, to understand the role of DAT gene for impaired social mechanisms
“Himalayan Bridge”: A New Unstable Suspended Bridge to Investigate Rodents' Venturesome Behavior
No full textWhile both risk-taking and avoidant behaviors are necessary for survival, their imbalanced expression can lead to impulse-control and anxiety disorders, respectively. In laboratory rodents, the conflict between risk proneness and anxiety can be studied by using their innate fear of heights. To explore this aspect in detail and investigate venturesome behavior, here we used a “Himalayan Bridge,” a rat-adapted version of the suspended wire bridge protocol originally developed for mice. The apparatus is composed of two elevated scaffolds connected by bridges of different lengths and stability at 1 m above a foam rubber-covered floor. Rats were allowed to cross the bridge to reach food, and crossings, pawslips, turnabouts, and latencies to cross were measured. Given the link between risky behavior and adolescence, we used this apparatus to investigate the different responses elicited by a homecage mate on the adolescent development of risk-taking behavior. Thus, 24 wild-type (WT) subjects were divided into three different housing groups: WT rats grown up with WT adult rats; control WT adolescent rats (grown up with WT adolescents), which showed a proclivity to risk; and WT rats grown up with an adult rat harboring a truncated mutation for their dopamine transporter (DAT). This latter group exhibited risk-averse responses reminiscent of lower venturesomeness. Our results suggest that the Himalayan Bridge may be useful to investigate risk perception and seeking; thus, it should be included in the behavioral phenotyping of rat models of psychiatric disorders and cognitive dysfunctions
Exploring the effectiveness of targeted memory reactivation on emotional implicit memory
No full textIntroduction: Targeted Memory Reactivation (TMR) is a technique employed to enhance memory consolidation by reactivating specific memory traces during sleep. Negative attentional bias (AB), characterized by a tendency to preferentially focus on negative rather than positive stimuli, has been demonstrated to play a role in perpetuating negative emotions and memories. TMR could potentially affect AB by selectively reactivating positive memories, thus influencing emotional memory processing. This study aimed to investigate the effectiveness of TMR in modulating emotional implicit memories to attenuate negative AB.
Materials and Methods: Eight female students (mean age ± standard deviation, 21.50 ± 2.45) participated in a between-subjects design involving the assessment of AB through a modified version of the Dot-Probe Task (DPT) before (T1) and after (T2) a nocturnal sleep with acoustic stimulation (ASTMR vs. ASCONTROL) during slow-wave sleep. During the DPT, participants were simultaneously presented with a positive and a negative emotional face, followed by a probe that equally replaced one of the emotional stimuli (positive condition/negative condition). The subjects' assignment was to indicate the position of the probe (left vs. right) using the keyboard. AB in DPT was measured by comparing reaction times (RTs) in positive and negative conditions, with faster responses obtained when the probe appeared in the previously attended spatial location. Concurrently with the keyboard response, participants were exposed to two different auditory cues for positive and negative conditions. In the ASTMR group, participants were exposed during sleep to the auditory stimulus linked to the positive condition during the DPT. In the ASCONTROL group, a novel sound was presented. To assess the effect of TMR, a mixed ANOVA was applied to the RTs of the DPT, with condition (negative/positive), session (T1/T2), and group (ASTMR/ASCONTROL) as within/between factors. To evaluate the EEG correlates of TMR during sleep, an event-related spectral power perturbation of nocturnal stimulations was computed, comparing the two experimental groups using independent samples t-Test.
Results: Analysis of DPT showed a significant effect of TMR on RTs (group x session: p<0.001). Post hoc comparisons highlighted a reduction of both positive and negative RTs in the ASTMR group compared to the ASCONTROL group. The comparisons on sleep EEG correlates of TMR evidenced an increase in spindle activity around 500 and 1000 ms post-stimulation on the whole topography for ASTMR compared to the ASCONTROL group (p<0.05). The midline and parieto-occipital sites in the ASTMR group also showed increased delta/theta activity (p<0.05) around 1000 ms post-stimulation.
Conclusions: The findings indicate an effect of TMR in modulating attentional processes associated with emotional stimuli with no specificity for the stimulus valence. The electrophysiological correlates of nocturnal stimulation involve rhythms typically engaged in sleep-dependent memory consolidation, supporting the effectiveness of memory reactivation. The reduction in RTs associated with both positive and negative stimuli seems to suggest that TMR effectiveness may be contingent upon previous associative learning at the explicit level, implying a nuanced interplay between different memory processes. Further research is warranted to unravel these intricate interactions and refine the TMR application also for therapeutic and cognitive enhancement purposes
Effects of physical activity on cognitive functioning: the role of cognitive reserve and active ageing
No full textBackground: The increase in average life expectancy necessitates the identification of
possible mechanisms capable of promoting “active aging” to ensure adequate levels of global functioning.
Numerous studies show that regular physical activity promotes, even in the elderly, a state
of functional psychophysical well-being capable of slowing down age-related cognitive decline. This
study aimed to clarify whether, and how, the intensity of physical activity can modulate cognitive
and executive skills by influencing specific psychological variables. Methods: Our sample consisted
of 151 senior subjects divided into hikers (HIK), gentle gymnastics (GYM), and sedentary (SED), who
practice intense, moderate, and reduced physical activity, respectively. A battery of psychological
questionnaires was administrated to evaluate attentional skills, decision-making, the ability to implement
targeted behaviors, perceived self-efficacy, and psychophysical well-being. We included:
the Mini-Mental State Examination, Cognitive Reserve Index Questionnaire, General Self-Efficacy
Scale, Letter Cancellation Test, Everyday Competence Questionnaire, and Geriatric Depression Scale
(GDS). Results: Comparisons between the scores reported by the three groups showed that the HIK
group differs from the others with respect to most of the measurements, presenting better mood
and cognitive performance, and a specific psychological profile. On the contrary, the GYM group
appeared to have a greater affinity with the SED group than with the HIK group, both cognitively
and psychologically. Conclusions: Types of physical activity, as well as the intensity and frequency
with which they are practiced, are factors that promote an active aging process, protecting the
psychophysical well-being and overall cognitive functioning of the elderly
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
[Newspaper Clipping: Author Claims Evidence of Second JFK Assassin #1]
No full textNewspaper article titled "Author Claims Evidence of Second JFK Assassin." The article states that author Richard J. Whalen concluded "that there is circumstantial evidence to support the theory of a second assassin in the shooting of President John F. Kennedy.
Also By The Same Author: AKTiveAuthor, a Citation Graph Approach to Name Disambiguation
No full textThe desire for definitive data and the semantic web drive for inference over heterogeneous data sources requires co-reference resolution to be performed on those data. In particular, name disambiguation is required to allow accurate publication lists, citation counts and impact measures to be determined. This paper describes a graph-based approach to author disambiguation on large-scale citation networks. Using self-citation, co-authorship and document source analyses, AKTiveAuthor clusters papers, achieving precision of 0.997 and recall of 0.818 over a test group of eight surname clusters
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