Inhibitory feedback from the motor circuit gates mechanosensory processing in C. elegans

Animals must integrate sensory cues with their current behavioral context to generate a suitable response. How this integration occurs is poorly understood. Previously we developed high throughput methods to probe neural activity in populations of Caenorhabditis elegans and discovered that the animal's mechanosensory processing is rapidly modulated by the animal's locomotion. Specifically we found that when the worm turns it suppresses its mechanosensory-evoked reversal response. Here we report that C. elegans use inhibitory feedback from turning-associated neurons to provide this rapid modulation of mechanosensory processing. By performing high-throughput optogenetic perturbations triggered on behavior, we show that turning associated neurons SAA, RIV and/or SMB suppress mechanosensory-evoked reversals during turns. We find that activation of the gentle-touch mechanosensory neurons or of any of the interneurons AIZ, RIM, AIB and AVE during a turn is less likely to evoke a reversal than activation during forward movement. Inhibiting neurons SAA, RIV and SMB during a turn restores the likelihood with which mechanosensory activation evokes reversals. Separately, activation of premotor interneuron AVA evokes reversals regardless of whether the animal is turning or moving forward. We therefore propose that inhibitory signals from SAA, RIV and/or SMB gate mechanosensory signals upstream of neuron AVA. We conclude that C. elegans rely on inhibitory feedback from the motor circuit to modulate its response to sensory stimuli on fast timescales. This need for motor signals in sensory processing may explain the ubiquity in many organisms of motor-related neural activity patterns seen across the brain, including in sensory processing areas

Ecological compatibility of GM crops and biological control

Insect-resistant and herbicide-tolerant genetically modified (GM) crops pervade many modern cropping systems (especially field-cropping systems), and present challenges and opportunities for developing biologically based pest-management programs. Interactions between biological control agents (insect predators, parasitoids, and pathogens) and GM crops exceed simple toxicological relationships, a priority for assessing risk of GM crops to non-target species. To determine the compatibility of biological control and insect-resistant and herbicide-tolerant GM crop traits within integrated pest-management programs, this synthesis prioritizes understanding the bi-trophic and prey/host-mediated ecological pathways through which natural enemies interact within cropland communities, and how GM crops alter the agroecosystems in which natural enemies live. Insect-resistant crops can affect the quantity and quality of non-prey foods for natural enemies, as well as the availability and quality of both target and non-target pests that serve as prey/hosts. When they are used to locally eradicate weeds, herbicide-tolerant crops alter the agricultural landscape by reducing or changing the remaining vegetational diversity. This vegetational diversity is fundamental to biological control when it serves as a source of habitat and nutritional resources. Some inherent qualities of both biological control and GM crops provide opportunities to improve upon sustainable IPM systems. For example, biological control agents may delay the evolution of pest resistance to GM crops, and suppress outbreaks of secondary pests not targeted by GM plants, while herbicide-tolerant crops facilitate within-field management of vegetational diversity that can enhance the efficacy of biological control agents. By examining the ecological compatibility of biological control and GM crops, and employing them within an IPM framework, the sustainability and profitability of farming may be improved

C. ELEGANS BEHAVIORS AND THEIR MECHANOSENSORY DRIVERS

One of the fundamental problems in neuroscience is how behavior is generated from sensory input and internal neural states, such as the animal’s behavioral context. We present new methods and findings to address this by studying the model organism Caenorhabditis elegans. With a fully mapped connectome of 302 neurons, this nematode is a particularly good candidate to investigate the neural basis of behavior due to its rich history of scientific research and its optical transparency. First, we showcase an instrument that can record panneuronal calcium activity in the head of a freely moving worm at single neuron resolution. We find multiple neurons have correlated activity with behaviors such as forward, backward, and turning locomotion. We also developed a high-throughput method to measure sensorimotor transformations from soft touch stimulation to locomotory behavior. We use automated behavior segmentation and reverse correlation to reveal how mechanosensory stimuli influences behavioral transitions. Our results show that C. elegans make locomotory decisions based on both the temporal history of the stimulus and its own behavioral context in a predictable manner. Continuing our investigation of the soft touch circuit, we developed a more advanced apparatus that can probe worm behavioral response to excitatory and inhibitory optogenetic stimuli with sub-animal level spatial resolution. This instrument has the ability to target the heads and tails of many animals in parallel, and can tailor the stimuli based on real-time behavior information. Preliminary experiments demonstrate that it can evoke the same optogenetically driven touch response akin to mechanical activation of the touch neurons

Response of Extreme Rainfall for Landfalling Tropical Cyclones Undergoing Extratropical Transition to Projected Climate Change: Hurricane Irene (2011)

Extreme rainfall and flooding associated with landfalling tropical cyclones (TCs) have large societal impacts, both in fatalities and economic losses. This study examines the response of TC rainfall to climate change projected under future anthropogenic greenhouse emissions, focusing on Hurricane Irene, which produced severe flooding across the Northeastern United States in August 2011. Numerical simulations are made with the Weather Research and Forecasting model, placing Irene in the present‐day climate and one projected for the end of 21st century climate represented by Phase 5 of the Coupled Model Intercomparison Project Representative Concentration Pathway 8.5 scenario. Projected future changes to surface and atmospheric temperature lead to a storm rainfall increase of 32% relative to the control run, exceeding the rate expected by the Clausius‐Clapeyron relation given a ~3‐K lower atmospheric warming. Analyses of the atmospheric water balance highlight contributions to the increase in rainfall rate from both increased circulation strength and atmospheric moisture. Storm rainfall rate shows contrasting response to global warming during TC and extratropical transition periods. During the TC phase, Irene shows a significant increase of storm rainfall rate in inner core regions. This increase shifts to outer rainbands as Irene undergoes extratropical transition, collocated with the maximum tangential wind increase and the change of secondary circulation strength. Changes of storm track from the control run to global warming projections play a role in the change of spatial rainfall pattern. Distinct roles of surface and atmospheric warming in storm rainfall and structure changes are also examined

Mirror Clock: A Strategy for Identifying Atomic Clock Frequency Jumps

Atomic clock frequency jumps directly influence the accuracy and reliability of timekeeping systems. The necessary corrections are typically implemented by postprocessing mutual comparison data between multiple atomic clocks based on the overly strict assumption that these atomic clocks are independent of each other. This paper describes the concept of a mirror clock, which enables atomic clock frequency jumps to be identified in real time without any assumptions. By comparing whether the real measured data and a corresponding mirror clock prediction fall within a confidence interval determined by the uncertainty of past physical clock data, atomic clock frequency jumps can be effectively identified and corrected. The results of several experiments using three hydrogen masers verify that the precision and recall of simultaneous jump identification reach 96.41% and 73.49%, respectively

Towards Dynamical Seasonal Forecast of Extratropical Transition in the North Atlantic

Extratropical transition can extend the threat of tropical cyclones into the midlatitudes and modify it through expansion of rainfall and wind fields. Despite the scientific and socioeconomic interest, the seasonal forecast of extratropical transition has received little attention. The GFDL High‐Resolution Forecast‐Oriented Low Ocean Resolution (FLOR) model (HiFLOR) shows skill in seasonal forecasts of tropical cyclone frequency as well as major hurricanes. A July‐initialized 12‐member ensemble retrospective seasonal forecast experiment with HiFLOR in the North Atlantic is conducted, representing one of the very first attempts to predict the extratropical transition activity months in advance. HiFLOR exhibits retrospective skill in seasonal forecasts of basin‐wide and regional ET activity relative to best track and reanalysis data. In contrast, the skill of HiFLOR in predictions of non‐ET activity is limited. Future work targeted at improved predictions of non‐ET storms provides a path for enhanced TC activity forecasting

Example of a worm aborting a turn and reversing when neuron AVA was activated following the onset of the turn.

Animals express Chrimson in neuron AVA (strain name: AML17). Stimulation was delivered upon the onset of a turn in closed loop. Green dot denotes the animal’s head. Green line denotes its centerline. Yellow line shows the trajectory of a point midway along the animal’s centerline over the past 10 s. Red indicates area illuminated by red light. (MP4)</p

Example of a worm receiving optogenetic stimulation of its gentle-touch mechanosensory neurons during the onset of a turn.

Recording is from [19]. Animals express Chrimson in gentle-touch mechanosensory neurons (strain name: AML67). This worm does not reverse in response to stimulation. Stimuli was triggered in closed-loop by the animal’s turn. Green dot denotes the animal’s head. Green line denotes its centerline. Yellow line shows the trajectory of a point midway along the animal’s centerline over the past 10 s. Red indicates area illuminated by red light. (MP4)</p

List of optogenetic measurements performed during behavior.

List of optogenetic measurements performed during behavior.</p