Neural network organization for courtship-song feature detection in Drosophila

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Lack of long-term changes in circadian,locomotor, and cognitive functions in acute and chronic MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) mouse models of parkinson’s disease

In addition to the hallmark motor disorders in Parkinson’s disease (PD) patients, nonmotor symptoms have attracted increasing attention. Among the nonmotor symptoms, sleep disturbances and cognitive deficits are frequently reported and contribute to a decrease in the quality of life. The pathophysiology of cognitive and sleep-wake abnormalities in PD is poorly understood partially due to the lack of appropriate animal models that fully replicate the entire pathological and behavioral spectrum of the disease. In this study, we undertook a long-term evaluation of circadian, locomotor and cognitive abilities in both acute and chronic MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine)-treated mouse models. Activity rhythms and locomotor activity were assayed under light-dark cycles, constant darkness, or constant light, re-entrainment to shifts of the light-dark cycle, and a behavioral masking paradigm. Cognitive abilities were assessed using a radial water maze task. Although both acute and chronic treatment regimes induced 70% degeneration of dopaminergic neurons in the substantia nigra, neither circadian nor cognitive alterations were observed even after nearly 1?yr. During aging, there was a significant decrease of locomotor activity and of several circadian parameters without any exacerbation in MPTP-treated animals. These results emphasize the limitations of the MPTP-treated mouse as an animal model of nonmotor symptoms of PD in addition to the already well-documented inadequacy to replicate cardinal motor features of the disease.     

Synthesis of Phase-shift Nanoemulsions with Narrow Size Distributions for Acoustic Droplet Vaporization and Bubble-enhanced Ultrasound-mediated Ablation

High-intensity focused ultrasound (HIFU) is used clinically to thermally ablate tumors. To enhance localized heating and improve thermal ablation in tumors, lipid-coated perfluorocarbon droplets have been developed which can be vaporized by HIFU. The vasculature in many tumors is abnormally leaky due to their rapid growth, and nanoparticles are able to penetrate the fenestrations and passively accumulate within tumors. Thus, controlling the size of the droplets can result in better accumulation within tumors. In this report, the preparation of stable droplets in a phase-shift nanoemulsion (PSNE) with a narrow size distribution is described. PSNE were synthesized by sonicating a lipid solution in the presence of liquid perfluorocarbon. A narrow size distribution was obtained by extruding the PSNE multiple times using filters with pore sizes of 100 or 200 nm. The size distribution was measured over a 7-day period using dynamic light scattering. Polyacrylamide hydrogels containing PSNE were prepared for in vitro experiments. PSNE droplets in the hydrogels were vaporized with ultrasound and the resulting bubbles enhanced localized heating. Vaporized PSNE enables more rapid heating and also reduces the ultrasound intensity needed for thermal ablation. Thus, PSNE is expected to enhance thermal ablation in tumors, potentially improving therapeutic outcomes of HIFU-mediated thermal ablation treatments.     

Looking for love under the ice: Using passive acoustics to detect burbot (Lota lota: Gadidae) spawning activity

1. Burbot (Lota lota: Gadidae) is a difficult species to manage effectively due to its preference for deep-water habitats and under-ice spawning behaviour, resulting in a poor understanding of its reproductive activity. However, the use of acoustic signalling by burbot as part of their mating system has recently been described and this behaviour may provide a means of investigating questions regarding the spatial and temporal distribution of spawning aggregations using passive acoustic monitoring.
2. We used audio and video recording to confirm that burbot vocalise and that these vocalisations can be detected under field conditions as well as to characterise the relationship between burbot acoustic signalling and spawning behaviour. We also evaluated the feasibility of locating and monitoring burbot spawning aggregations in real time using passive acoustics.
3. Burbot vocalisations were difficult to identify with only about 6% of the recordings containing calls being successfully identified as such in the field. Burbot vocalised more often between sundown and sunrise than during daylight hours. Calls recorded at night tended to be lower frequency, longer duration, and have lower bandwidth than those made during the day.
4. Burbot vocalisations could not be recorded in conjunction with video recordings of spawning activity, indicating that burbot may not call during active spawning, but may use acoustic communication to signal the onset of reproductive readiness and to form pre-spawning aggregations.
5. While burbot calls were readily identifiable, observers had a difficult time identifying burbot calls in real time under field conditions. Passive acoustic monitoring demonstrates considerable potential as a management tool to locate burbot spawning grounds and identify periods of activity, but may not be an appropriate technique for monitoring spawning activity in real time.

     

Automated acoustic monitoring of endangered common spadefoot toad populations reveals patterns of vocal activity

1. In the context of global amphibian decline, monitoring and restoration programmes are important. Acoustic monitoring is a possible approach for underwater vocalising species like the rapidly declining European common spadefoot toad (Pelobates fuscus). In this study, our aim was to design a dedicated software detector to be used in combination with programmable audio recorders to process the large amount of data generated by long-term acoustic monitoring and to use it for investigating the seasonal and circadian patterns of P. fuscus vocal activity.
2. The software detector targets advertisement calls of the species. Based on acoustic analysis of that call, we developed a detector that utilises both frequency and time features of the calls. Data collected during three breeding seasons in four known or potential P. fuscus breeding sites of north-eastern France were used to build a ground truth in order to test the performance of the detector. Then, we used the detector for analysing four acoustic monitoring campaigns conducted in two different sites over two breeding seasons to gain insight into the seasonal and circadian patterns of vocal activity of this species.
3. Evaluation of the P. fuscus call detector against a ground truth returned false-positive rates below 1.5% and true-positive rates ranging from 53% to 73%. These figures are compatible with long-term monitoring of the presence of the species. Running the software detector on standard hardware, the computation time for post-processing the 360 hr of a typical 3-month monitoring campaign was less than 1 day.
4. The seasonal pattern of P. fuscus underwater vocal activity is more complex than previously recognised. Over the whole ostensible 3-month breeding season, the actual time window for vocalising and breeding can last from a few days up to several weeks and may be split into clearly distinct episodes. When vocalisations occurred at both night- and daytime, the circadian vocal activity of P. fuscus occasionally proceeded uninterrupted for 24 hr but usually a several hour lull occurred immediately prior to sunset. When vocalisations occurred at both night- and daytime, the vocal activity pattern followed a bimodal distribution with a nocturnal highest peak of activity and a second peak occurring in the morning.
5. Our results demonstrate that it is feasible to monitor presence of P. fuscus in north-eastern France using a dedicated software detector combined with programmable audio recorders. Based on the outcomes of the detector applied to long-term audio data sets, we reveal temporal patterns of the vocal activity of the species and subsequently provide recommendations for attended and unattended acoustic monitoring.

     

Acoustic detection and acoustic habitat characterisation of the critically endangered white-bellied heron (Ardea insignis) in Bhutan

1. Growing developmental activities, such as hydropower construction, farm roads, and other human activities, are affecting the critically endangered white-bellied heron (WBH). Out of a known global population of 60, 28 individuals inhabit the river basin area and freshwater lakes and ponds of Bhutan. Several constraints impede continuous monitoring of endangered species, such as the isolated and cryptic nature of the species and the remoteness of its habitat; to date, there are no long-term reference data or techniques implemented for continuous monitoring of this species.
2. In this study, we designed acoustic detection and habitat characterisation methods using long-duration recordings from three habitat areas in Bhutan. Acoustic indices were extracted and used to implement a species-specific call detector and to generate habitat soundscape representations. Using WBH calls annotated in month-long recordings from a known site, a novel indices-based detector was implemented and tested. A total of 960 hr of continuous audio recordings from three habitats in Bhutan were analysed.
3. We found that a species call detector implemented using a combination of acoustic indices (that includes measures of spectral and temporal entropy and different angles of spectral ridges) has a correct detection rate of 81%. Additionally, visual inspection of the species’ acoustic habitat using long-duration false-colour spectrograms enabled qualitative assessment of acoustic habitat structure and other dominant acoustic events.
4. This study proposes a combined approach of species acoustic detection and habitat soundscape analysis for holistic acoustic monitoring of endangered species. As a direct outcome of this work, we documented acoustic reference data on the critically endangered WBH from multiple habitat areas and have analysed its temporal vocalisation patterns across sites.