Sounds in noise: Behavioral and neural studies of illusory continuity and discontinuity

ability to parse an auditory scene into meaningful components varies greatly between individuals; some are able to parse out and write down competing musical pieces while others struggle to understand each word whenever they have to converse in a noisy environment. Using a simple discrimination task, healthy, normally-heari ng adult participants were asked to judge whether a pure tone (with or without amplitude modulation) was continuous or contained a gap. One quarter of the participants consistently heard a gap when none was present, if the tone was accompanied by a higher-frequency noise burst with a lower edge beginning one octave away from the tone (that did not have any energy overlapping the tone). This novel form of informational masking (perceptual interference between components with non-overlapping sound energy) was named 'illusory auditory discontinuity\u2019. The phenomenon appears to reflect natural differences in auditory processing rather than differences in decision-making strategies because: (1) susceptibility to illusory discontinuity correlates with individual differences in auditory streaming (measured using a classical ABA sequential paradigm); and (2) electroencephalographic responses elicited by tones overlaid by short noise bursts (when these sounds are not the focus of attention) are significantly correlated with the occurrence of illusory auditory discontinuity in both an early event-related potential (ERP) component (40-66 ms), and a later ERP component (270-350 ms) after noise onset. Participants prone to illusory discontinuity also tended not to perceive the \u2018auditory continuity illusion\u2019 (in which a tone is heard continuing under a burst of noise centered on the tone frequency that completely masks it) at short noise durations, but reliably perceived the auditory continuity illusion at longer noise durations. These results suggest that a number of attributes describing how individuals differentially parse complex auditory scenes are related to individual differences in two potentially independent attributes of neural processing, reflected here by EEG waveform differences at ~50 msec and ~300 msec after noise onset. Neural correlates of the auditory continuity illusion were also investigated by adjusting masker loudness, so that when listeners were given physically identical stimuli, they correctly detected the gap in a target tone on some trials, while on other trials they reported the tone as continuous (experiencing illusory continuity). High er power of low-frequency EEG activity (in the delta-theta range, <6 Hz) was observed prior to the onset of tones that were subsequently judged as discontinuous, with no other consistent EEG differences found after the onset of tones. These data suggest that the occurrence of the continuity illusion may depend on the brain state that exists immediately before a trial begins

Auditory stimuli elicit hippocampal neuronal responses during sleep

To investigate how hippocampal neurons code behaviorally salient stimuli, we recorded from neurons in the CA1 region of hippocampus in rats while they learned to associate the presence of sound with water reward. Rats learned to alternate between two reward ports at which, in 50% of the trials, sound stimuli were presented followed by water reward after a 3-s delay. Sound at the water port predicted subsequent reward delivery in 100% of the trials and the absence of sound predicted reward omission. During this task, 40% of recorded neurons fired differently according to which of the two reward ports the rat was visiting. A smaller fraction of neurons demonstrated onset response to sound/nosepoke (19%) and reward delivery (24%). When the sounds were played during passive wakefulness, 8% of neurons responded with short latency onset responses; 25% of neurons responded to sounds when they were played during sleep. During sleep the short-latency responses in hippocampus are intermingled with long lasting responses which in the current experiment could last for 1–2 s. Based on the current findings and the results of previous experiments we described the existence of two types of hippocampal neuronal responses to sounds: sound-onset responses with very short latency and longer-lasting sound-specific responses that are likely to be present when the animal is actively engaged in the task

Automated monitoring and quantitative analysis of feeding behaviour in Drosophila

Food ingestion is one of the defining behaviours of all animals, but its quantification and analysis remain challenging. This is especially the case for feeding behaviour in small, genetically tractable animals such as Drosophila melanogaster. Here, we present a method based on capacitive measurements, which allows the detailed, automated and high-throughput quantification of feeding behaviour. Using this method, we were able to measure the volume ingested in single sips of an individual, and monitor the absorption of food with high temporal resolution. We demonstrate that flies ingest food by rhythmically extending their proboscis with a frequency that is not modulated by the internal state of the animal. Instead, hunger and satiety homeostatically modulate the microstructure of feeding. These results highlight similarities of food intake regulation between insects, rodents, and humans, pointing to a common strategy in how the nervous systems of different animals control food intake

Automated monitoring and quantitative analysis of feeding behaviour in Drosophila

Food ingestion is one of the defining behaviours of all animals, but its quantification and analysis remain challenging. This is especially the case for feeding behaviour in small, genetically tractable animals such as Drosophila melanogaster. Here, we present a method based on capacitive measurements, which allows the detailed, automated and high-throughput quantification of feeding behaviour. Using this method, we were able to measure the volume ingested in single sips of an individual, and monitor the absorption of food with high temporal resolution. We demonstrate that flies ingest food by rhythmically extending their proboscis with a frequency that is not modulated by the internal state of the animal. Instead, hunger and satiety homeostatically modulate the microstructure of feeding. These results highlight similarities of food intake regulation between insects, rodents, and humans, pointing to a common strategy in how the nervous systems of different animals control food intake

Individual Differences in Sound-in-Noise Perception Are Related to the Strength of Short-Latency Neural Responses to Noise

Important sounds can be easily missed or misidentified in the presence of extraneous noise. We describe an auditory illusion in which a continuous ongoing tone becomes inaudible during a brief, non-masking noise burst more than one octave away, which is unexpected given the frequency resolution of human hearing. Participants strongly susceptible to this illusory discontinuity did not perceive illusory auditory continuity (in which a sound subjectively continues during a burst of masking noise) when the noises were short, yet did so at longer noise durations. Participants who were not prone to illusory discontinuity showed robust early electroencephalographic responses at 40–66 ms after noise burst onset, whereas those prone to the illusion lacked these early responses. These data suggest that short-latency neural responses to auditory scene components reflect subsequent individual differences in the parsing of auditory scenes

Immunohistochemical Markers of Local Tissue Response to the Implantation of Products Made from PHA

В статье представлен анализ результатов применения моножильного шовного материала на основе полигидроксиалканоатов (ПГА) в сравнении с шовным материалом «Викрил» и «Капрофил» в эксперименте с кроликами породы шиншилла. Доказано, что применение шовного материала на основе ПГА сопровождается минимально выраженной местной реакцией тканейThe paper presents the analysis of the results of application of monofilament suture based on polyhydroxyalkanoates (PHAs) in comparison with suture materials “Vicryl” and “Kaprofil” in experiment with Chinchilla rabbits. It was proved that the use of the PHA-based suture is accompanied by minimally pronounced local tissue respons

The Use of Wound Dressings Based on Cellulose in Patients with Purulent Diseases of Soft Tissues

В статье представлены результаты клинических испытаний раневого покрытия на основе целлюлозы, нагруженного диоксидином, в сравнении с раневым покрытием «Гидроколл». Доказано, что при лечении больных с острой гнойной инфекцией мягких тканей раневое покрытие на основе целлюлозы более эффективно, способствует быстрому и интенсивному очищению и эпителизации инфицированных ранThe paper presents the results of clinical trials of wound dressing based on cellulose in comparison with wound dressing “Gidrokoll” in patients with acute purulent soft tissue infections. It is proved that the wound covering based on cellulose more efficient, contribute to the rapid and intensive purification and epithelialization of infected wound

Immunohistochemical Markers of Local Tissue Response to the Implantation of Products Made from PHA

В статье представлен анализ результатов применения моножильного шовного материала на основе полигидроксиалканоатов (ПГА) в сравнении с шовным материалом «Викрил» и «Капрофил» в эксперименте с кроликами породы шиншилла. Доказано, что применение шовного материала на основе ПГА сопровождается минимально выраженной местной реакцией тканейThe paper presents the analysis of the results of application of monofilament suture based on polyhydroxyalkanoates (PHAs) in comparison with suture materials “Vicryl” and “Kaprofil” in experiment with Chinchilla rabbits. It was proved that the use of the PHA-based suture is accompanied by minimally pronounced local tissue respons