Rising Sound Intensity: An Intrinsic Warning Cue Activating the Amygdala

Human subjects overestimate the change of rising intensity sounds compared with falling intensity sounds. Rising sound intensity has therefore been proposed to be an intrinsic warning cue. In order to test this hypothesis, we presented rising, falling, and constant intensity sounds to healthy humans and gathered psychophysiological and behavioral responses. Brain activity was measured using event-related functional magnetic resonance imaging. We found that rising compared with falling sound intensity facilitates autonomic orienting reflex and phasic alertness to auditory targets. Rising intensity sounds produced neural activity in the amygdala, which was accompanied by activity in intraparietal sulcus, superior temporal sulcus, and temporal plane. Our results indicate that rising sound intensity is an elementary warning cue eliciting adaptive responses by recruiting attentional and physiological resources. Regions involved in cross-modal integration were activated by rising sound intensity, while the right-hemisphere phasic alertness network could not be supported by this stud

Distributed Fiber Ultrasonic Sensor and Pattern Recognition Analytics

Ultrasound interrogation and structural health monitoring technologies have found a wide array of applications in the health care, aerospace, automobile, and energy sectors. To achieve high spatial resolution, large array electrical transducers have been used in these applications to harness sufficient data for both monitoring and diagnoses. Electronic-based sensors have been the standard technology for ultrasonic detection, which are often expensive and cumbersome for use in large scale deployments. Fiber optical sensors have advantageous characteristics of smaller cross-sectional area, humidity-resistance, immunity to electromagnetic interference, as well as compatibility with telemetry and telecommunications applications, which make them attractive alternatives for use as ultrasonic sensors. A unique trait of fiber sensors is its ability to perform distributed acoustic measurements to achieve high spatial resolution detection using a single fiber. Using ultrafast laser direct-writing techniques, nano-reflectors can be induced inside fiber cores to drastically improve the signal-to-noise ratio of distributed fiber sensors. This dissertation explores the applications of laser-fabricated nano-reflectors in optical fiber cores for both multi-point intrinsic Fabry–Perot (FP) interferometer sensors and a distributed phase-sensitive optical time-domain reflectometry (φ-OTDR) to be used in ultrasound detection. Multi-point intrinsic FP interferometer was based on swept-frequency interferometry with optoelectronic phase-locked loop that interrogated cascaded FP cavities to obtain ultrasound patterns. The ultrasound was demodulated through reassigned short time Fourier transform incorporating with maximum-energy ridges tracking. With tens of centimeters cavity length, this approach achieved 20kHz ultrasound detection that was finesse-insensitive, noise-free, high-sensitivity and multiplex-scalability. The use of φ-OTDR with enhanced Rayleigh backscattering compensated the deficiencies of low inherent signal-to-noise ratio (SNR). The dynamic strain between two adjacent nano-reflectors was extracted by using 3×3 coupler demodulation within Michelson interferometer. With an improvement of over 35 dB SNR, this was adequate for the recognition of the subtle differences in signals, such as footstep of human locomotion and abnormal acoustic echoes from pipeline corrosion. With the help of artificial intelligence in pattern recognition, high accuracy of events’ identification can be achieved in perimeter security and structural health monitoring, with further potential that can be harnessed using unsurprised learning

A Flight Sensory-Motor to Olfactory Histamine Circuit Mediates Olfactory Processing of Ecologically and Behaviorally Natural Stimuli

Environmental pressures have conferred species specific behavioral and morphological traits to optimize reproductive success. To optimally interact with their environment, nervous systems have evolved motor-to-sensory circuits that mediate the processing of its own reafference. Moth flight behavioral patterns to odor sources are stereotyped, presumably to optimize the likelihood of interacting with the odor source. In the moth Manduca sexta wing beating causes oscillatory flow of air over the antenna; because of this, odorant-antennal interactions are oscillatory in nature. Electroantennogram recordings on antennae show that the biophysical properties of their spiking activity can effectively track odors presented at the wing beat frequency. Psychophysical experiments using Manduca show that when odors are pulsed, as opposed to presented as a continuous stream, detection and discrimination thresholds are lowered. In this study, we characterized histamine immunoreactivity in the thoracic ganglia and brain of Manduca. We generated antibodies for and characterized the distribution of the histamine B receptor, the first known antibody for this receptor protein. Our results show an elaborate pair of neurons projecting from the mesothoracic ganglion to the brain, including axon innervation of the antennal lobe and antennal mechanosensory and motor centers. Additionally, histamine B receptor labeling overlapped with a subset of GABAergic and peptidergic local interneurons. Next, we characterized the response properties of these cells within the context of fictive flight behavior and found a tonic increase in activity. Furthermore, disrupting this circuit, with surgical ablation and pharmacology, disrupts antennal lobe projection neurons from entraining to odors presented at a natural 20 Hz frequency, as well as behavioral measures of detection and discrimination thresholds. Finally, we characterized the relationship between motor patterns/behaviors, and circuit structure of this pair of histamine immunoreactive neurons. Specifically, presence of MDHn axon collaterals entering the antennal lobe is correlated with olfactory-guided target approach behaviors in crepuscular and nocturnal moths who require stereotyped zigzagging and wing beating behaviors for locating an olfactory target have axonal ramifications in the antennal lobe. This study is the first characterization of a motor to olfactory corollary discharge circuit in invertebrates and may represent the first characterization of a higher order corollary discharge circuit in an invertebrate model

A trillion frames per second: the techniques and applications of light-in-flight photography

Cameras capable of capturing videos at a trillion frames per second allow to freeze light in motion, a very counterintuitive capability when related to our everyday experience in which light appears to travel instantaneously. By combining this capability with computational imaging techniques, new imaging opportunities emerge such as three dimensional imaging of scenes that are hidden behind a corner, the study of relativistic distortion effects, imaging through diffusive media and imaging of ultrafast optical processes such as laser ablation, supercontinuum and plasma generation. We provide an overview of the main techniques that have been developed for ultra-high speed photography with a particular focus on `light-in-flight' imaging, i.e. applications where the key element is the imaging of light itself at frame rates that allow to freeze it's motion and therefore extract information that would otherwise be blurred out and lost.Comment: Published in Reports on progress in Physic