A scalable implementation of the recursive least-squares algorithm for training spiking neural networks.

Training spiking recurrent neural networks on neuronal recordings or behavioral tasks has become a popular way to study computations performed by the nervous system. As the size and complexity of neural recordings increase, there is a need for efficient algorithms that can train models in a short period of time using minimal resources. We present optimized CPU and GPU implementations of the recursive least-squares algorithm in spiking neural networks. The GPU implementation can train networks of one million neurons, with 100 million plastic synapses and a billion static synapses, about 1,000 times faster than an unoptimized reference CPU implementation. We demonstrate the code's utility by training a network, in less than an hour, to reproduce the activity of > 66, 000 recorded neurons of a mouse performing a decision-making task. The fast implementation enables a more interactive in-silico study of the dynamics and connectivity underlying multi-area computations. It also admits the possibility to train models as in-vivo experiments are being conducted, thus closing the loop between modeling and experiments.

Sensitivity optimization of a rhodopsin-based fluorescent voltage indicator.

The ability to optically image cellular transmembrane voltages at millisecond-timescale resolutions can offer unprecedented insight into the function of living brains in behaving animals. Here, we present a point mutation that increases the sensitivity of Ace2 opsin-based voltage indicators. We use the mutation to develop Voltron2, an improved chemigeneic voltage indicator that has a 65% higher sensitivity to single APs and 3-fold higher sensitivity to subthreshold potentials than Voltron. Voltron2 retained the sub-millisecond kinetics and photostability of its predecessor, although with lower baseline fluorescence. In multiple in vitro and in vivo comparisons with its predecessor across multiple species, we found Voltron2 to be more sensitive to APs and subthreshold fluctuations. Finally, we used Voltron2 to study and evaluate the possible mechanisms of interneuron synchronization in the mouse hippocampus. Overall, we have discovered a generalizable mutation that significantly increases the sensitivity of Ace2 rhodopsin-based sensors, improving their voltage reporting capability.

Effect of High Jugular Bulb on the Hearing Loss Characteristics in Patients With LVAS: A Pilot Study.

OBJECTIVE: Both large vestibular aqueduct syndrome (LVAS) and high jugular bulb (HJB) are regarded as abnormalities commonly seen on the temporal bone CT. High jugular bulb has been found to erode the vestibular aqueduct, and there are several studies on jugular bulb vestibular aqueduct dehiscence. However, there is no study that specifically reports LVAS with concurrent HJB and its hearing loss relatedness. This study presents the pure tone audiometry differences between LVAS with HJB, and LVAS without HJB. METHODS: This was a case control study involving 36 bilateral LVAS with concurrent unilateral HJB patients, total of 72 ears. Intra-person comparison was done, by dividing ears into two groups: the case group, 36 ears (LVAS with HJB); and the control group, 36 ears (LVAS without HJB). Air conduction thresholds (250-4000 Hz), bone conduction thresholds (250-1000 Hz), and air bone gap (250-1000 Hz) were analyzed and compared between groups. RESULT: There were statistically significant differences in AC thresholds at 250, 500, 2000, and 4000 Hz between the groups, p < 0.05. But there was no statistical significant difference at 1000 Hz, p > 0.05. There were statistical significant differences in BC thresholds at 250 and 500 Hz, p < 0.05, but there was no statistical difference at 1000 Hz. There were no significant differences in air bone gap at 250, 500, and 1000 Hz between the two groups. CONCLUSION: LVAS with concurrent HJB was found to have higher air conduction thresholds, especially at 250, 500, 2000, and 4000 Hz. Bone conduction thresholds were higher at 250 and 500 Hz. Air bone gap at 250, 500, and 1000 Hz, were not significantly higher in LVAS with concurrent HJB.

Urban gardening and neglected and underutilized species in Salvador, Bahia, Brazil.

BACKGROUND: Urban agriculture has been evidenced as a food production and environmental sustainability strategy, although it faces many obstacles in Latin American countries. Additionally, in urban areas, low consumption of fruit and greenery is noticeable, along with loss in food diversity, including the neglected and underutilized species (NUS), which involve potential to strengthen local food systems. For this reason, this work has sought to map urban gardens in the city of Salvador, Bahia, Brazil, characterizing their gardeners, and to systematize information regarding food produced and the use of NUS. METHODS: The municipality's urban gardens were mapped and data was collected from the gardeners. The study included two steps: (i) garden localization; (ii) on-site visits for interviews with gardeners and verification of cultivated food, destination of production, availability, and use of NUS. RESULTS: Eighteen active food gardens were located, seventeen of which participated in the study: eight (8) communal (UCG) and nine (9) private (UPG). Respondents were on average 55.76 years old, mostly (52.9%) male, working at UPG (88.9%). Women predominated in the UCG (87.5%), with higher levels of education. For 52.9% of the interviewees, the garden was their main source of income. Food produced at the urban gardens was consumed by 82.4% of the gardeners and their families. In 70.6% of the gardens, production was also sold, while 47.1% donated. During the survey, 59 NUS were found and 76.5% of respondents reported consuming 19 of the species. NUS leaves, fruits, and seeds were found to be eaten raw, boiled, or sautéed in various preparations, especially Coleus amboinicus Lour. (76.5%), Eryngium foetidum L. (35.3%), Talinum fruticosum (L.) Juss., and Pereskia aculeata Mill (both 29.4%). Occurrence and utilization of NUS did not present significant associations with the gardens or gardeners (p > 0.05). CONCLUSIONS: Salvador urban gardens, even in small numbers and without government support, have produced affordable food for the local population, preserved food diversity, and the tradition of NUS cultivation and use. Thus, urban gardens are reaffirmed as relevant spaces that should be included in public policies in order to promote food and nutritional security, biodiversity, and urban environmental sustainability.

PURL: Supplemental oxygen: More isn't always better.

A recent study says that in certain populations, supplemental oxygen above certain levels can increase mortality.

Neural Evolution of Context-Dependent Fly Song.

It is unclear where in the nervous system evolutionary changes tend to occur. To localize the source of neural evolution that has generated divergent behaviors, we developed a new approach to label and functionally manipulate homologous neurons across Drosophila species. We examined homologous descending neurons that drive courtship song in two species that sing divergent song types and localized relevant evolutionary changes in circuit function downstream of the intrinsic physiology of these descending neurons. This evolutionary change causes different species to produce divergent motor patterns in similar social contexts. Artificial stimulation of these descending neurons drives multiple song types, suggesting that multifunctional properties of song circuits may facilitate rapid evolution of song types.

PURL: First-time, mild diverticulitis: Antibiotics or watchful waiting?

Don't jump to antibiotic Tx for mild, uncomplicated diverticulitis, a recent RCT says. Observation may be just as effective.

Correction: Return Customers: Foraging Site Fidelity and the Effect of Environmental Variability in Wide-Ranging Antarctic Fur Seals.

[This corrects the article DOI: 10.1371/journal.pone.0120888.].

Habitat use and sex-specific foraging behaviour of Adélie penguins throughout the breeding season in Adélie Land, East Antarctica.

BACKGROUND: Marine predators are ecosystem sentinels because their foraging behaviour and reproductive success reflect the variability occurring in the lower trophic levels of the ecosystem. In an era of environmental change, monitoring top predators species can provide valuable insights into the zones of ecological importance that need to be protected. In this context, we monitored the Adélie penguin (Pygoscelis adeliae) as a bio-indicator near Dumont d'Urville, an area of the East Antarctic sector currently being considered for the establishment of a Marine Protected Area (MPA), using GPS-based tracking tags during the 2012/13 austral summer breeding season. RESULTS: The habitat use and foraging areas of the penguins differed by breeding stage and sex and were strongly associated with patterns in bathymetry and sea-ice distribution. The first trips, undertaken during the incubation phase, were longer than those during the guard phase and were associated with the northern limit of the sea-ice extent. During the guard phase, birds strongly depended on access to a polynya, a key feature in Antarctic marine ecosystem, in the vicinity of the colony. The opening of the ice-free area was synchronous with the hatching of chicks. Moreover, a sex-specific use of foraging habitat observed only after hatching suggests sex-specific differences in the diet in response to intra-specific competition. CONCLUSIONS: Sea-ice features that could be affected by the climate change were important factors for the use of foraging habitat by the Adélie penguins. The extent of the foraging area observed in this study is congruent with the area of the proposed MPA. However, both penguin behavior and their environment should be monitored carefully.

Return customers: foraging site fidelity and the effect of environmental variability in wide-ranging antarctic fur seals.

Strategies employed by wide-ranging foraging animals involve consideration of habitat quality and predictability and should maximise net energy gain. Fidelity to foraging sites is common in areas of high resource availability or where predictable changes in resource availability occur. However, if resource availability is heterogeneous or unpredictable, as it often is in marine environments, then habitat familiarity may also present ecological benefits to individuals. We examined the winter foraging distribution of female Antarctic fur seals, Arctocephalus gazelle, over four years to assess the degree of foraging site fidelity at two scales; within and between years. On average, between-year fidelity was strong, with most individuals utilising more than half of their annual foraging home range over multiple years. However, fidelity was a bimodal strategy among individuals, with five out of eight animals recording between-year overlap values of greater than 50%, while three animals recorded values of less than 5%. High long-term variance in sea surface temperature, a potential proxy for elevated long-term productivity and prey availability, typified areas of overlap. Within-year foraging site fidelity was weak, indicating that successive trips over the winter target different geographic areas. We suggest that over a season, changes in prey availability are predictable enough for individuals to shift foraging area in response, with limited associated energetic costs. Conversely, over multiple years, the availability of prey resources is less spatially and temporally predictable, increasing the potential costs of shifting foraging area and favouring long-term site fidelity. In a dynamic and patchy environment, multi-year foraging site fidelity may confer a long-term energetic advantage to the individual. Such behaviours that operate at the individual level have evolutionary and ecological implications and are potential drivers of niche specialization and modifiers of intra-specific competition.

Mosquito (Aedes aegypti) flight tones: frequency, harmonicity, spherical spreading, and phase relationships.

Mosquito flight produces a tone as a side effect of wing movement; this tone is also a communication signal that is frequency-modulated during courtship. Recordings of tones produced by tethered flying male and female Aedes aegypti were undertaken using pairs of pressure-gradient microphones above and below, ahead and behind, and to the left and right over a range of distances. Fundamental frequencies were close to those previously reported, although amplitudes were lower. The male fundamental frequency was higher than that of the female and males modulated it over a wider range. Analysis of harmonics shows that the first six partials were nearly always within 1 Hz of integer multiples of the fundamental, even when the fundamental was being modulated. Along the front-back axis, amplitude attenuated as a function of distance raised to the power 2.3. Front and back recordings were out of phase, as were above and below, while left and right were in phase. Recordings from ahead and behind showed quadratic phase coupling, while others did not. Finally, two methods are presented for separating simultaneous flight tones in a single recording and enhancing their frequency resolution. Implications for mosquito behavior are discussed.

The effect of retinal defocus on simple eye-hand and eye-foot reaction time in traumatic brain injury (TBI).

PRIMARY OBJECTIVE: The purpose of the experiment was to assess the effect of retinal defocus on simple eye-hand (E-H) and eye-foot (E-F) reaction time (RT) in traumatic brain injury (TBI). DESIGN AND METHODS: Sixteen subjects with traumatic brain injury (five males and 11 females; aged 22-34 years) participated in the experiment. These were compared with 16 visually-normal, age/gender-match subjects. Retinal defocus was introduced optically (plano, +1, +2, +3, +4, +10D and +2D × 90) in the spectacle plane with binocular viewing. E-H and E-F RT were assessed binocularly using the RT-2S Simple Reaction Time Tester (Advanced Therapy Products, Glen Allen, VA). The test target colour and angular subtense simulated a conventional red/green traffic signal at 120 feet. RESULTS: There was no significant effect (p > 0.05) of retinal defocus on either E-H or E-F RT in each population. There was a significant effect (p < 0.05) of TBI on both E-H and E-F RT as compared with the normative data, with it being longer and more variable in TBI. Each RT condition was longest in those with moderate TBI. CONCLUSIONS: Both RTs were robust to retinal defocus, thus suggesting central nervous system insensitivity for this simple RT task. However, the increased RTs and related variability found in TBI, especially in moderate TBI, have potential safety implications (e.g. driving a car, ambulating).

Multi-channel acoustic recording and automated analysis of Drosophila courtship songs.

BACKGROUND: Drosophila melanogaster has served as a powerful model system for genetic studies of courtship songs. To accelerate research on the genetic and neural mechanisms underlying courtship song, we have developed a sensitive recording system to simultaneously capture the acoustic signals from 32 separate pairs of courting flies as well as software for automated segmentation of songs. RESULTS: Our novel hardware design enables recording of low amplitude sounds in most laboratory environments. We demonstrate the power of this system by collecting, segmenting and analyzing over 18 hours of courtship song from 75 males from five wild-type strains of Drosophila melanogaster. Our analysis reveals previously undetected modulation of courtship song features and extensive natural genetic variation for most components of courtship song. Despite having a large dataset with sufficient power to detect subtle modulations of song, we were unable to identify previously reported periodic rhythms in the inter-pulse interval of song. We provide detailed instructions for assembling the hardware and for using our open-source segmentation software. CONCLUSIONS: Analysis of a large dataset of acoustic signals from Drosophila melanogaster provides novel insight into the structure and dynamics of species-specific courtship songs. Our new system for recording and analyzing fly acoustic signals should therefore greatly accelerate future studies of the genetics, neurobiology and evolution of courtship song.

Behavioral observations and sound recordings of free-flight mating swarms of Ae. Aegypti (Diptera: Culicidae) in Thailand.

Sound plays an important role in the mating behavior of mosquitoes, including Aedes aegypti (L). Males orient to the fundamental wing beat frequency of females, and both sexes actively modulate their flight tone before mating to converge at harmonic frequencies. The majority of studies on mosquito mating acoustics have been conducted in the laboratory using tethered individuals. In this study, we present the first free-flight recording of naturally forming Ae. aegypti swarms in Thailand. We describe mating behaviors and present results on the flight tone frequency and dynamics of wild pairs in free flight. To assess the importance of these behaviors in vector control programs, especially those using genetically modified mosquitoes, it will be critical to use methods, such as those described in this work, to measure mosquito mating behaviors in the field.

Adaptive auditory risk assessment in the dogbane tiger moth when pursued by bats.

Moths and butterflies flying in search of mates risk detection by numerous aerial predators; under the cover of night, the greatest threat will often be from insectivorous bats. During such encounters, the toxic dogbane tiger moth, Cycnia tenera uses the received intensity, duration and emission pattern of the bat's echolocation calls to determine when, and how many, defensive ultrasonic clicks to produce in return. These clicks, which constitute an acoustic startle response, act as warning signals against bats in flight. Using an integrated test of stimulus generalization and dishabituation, here we show that C. tenera is able to discriminate between the echolocation calls characteristic of a bat that has only just detected it versus those of a bat actively in pursuit of it. We also show that C. tenera habituates more profoundly to the former stimulus train ('early attack') than to the latter ('late attack'), even though it was initially equally responsive to both stimuli. Matched sensory and behavioural data indicate that reduced responsiveness reflects habituation and is not merely attributable to sensory adaptation or motor fatigue. In search of mates in the face of bats, C. tenera's ability to discriminate between attacking bats representing different levels of risk, and to habituate less so to those most dangerous, should function as an adaptive cost-benefit trade-off mechanism in nature.

Tiger moths and the threat of bats: decision-making based on the activity of a single sensory neuron.

Echolocating bats and eared moths are a model system of predator-prey interaction within an almost exclusively auditory world. Through selective pressures from aerial-hawking bats, noctuoid moths have evolved simple ears that contain one to two auditory neurons and function to detect bat echolocation calls and initiate defensive flight behaviours. Among these moths, some chemically defended and mimetic tiger moths also produce ultrasonic clicks in response to bat echolocation calls; these defensive signals are effective warning signals and may interfere with bats' ability to process echoic information. Here, we demonstrate that the activity of a single auditory neuron (the A1 cell) provides sufficient information for the toxic dogbane tiger moth, Cycnia tenera, to decide when to initiate defensive sound production in the face of bats. Thus, despite previous suggestions to the contrary, these moths' only other auditory neuron, the less sensitive A2 cell, is not necessary for initiating sound production. However, we found a positive linear relationship between combined A1 and A2 activity and the number of clicks the dogbane tiger moth produces.

Periodic orbit analysis demonstrates genetic constraints, variability, and switching in Drosophila courtship behavior.

We use symbolic dynamics to describe Drosophila courtship communication. We posit that behavior should be defined in terms of irreducible periodic orbits of fundamental acts. This leads to a first operational definition of behavior, which allows for a fine grained quantitative analysis of behavior. We obtain evidence that during Drosophila courtship, individual characteristics of the protagonists are exchanged (predominantly from the male to the female) and that males in the presence of fruitless males perform a behavioral switch from male to female behavior.