Animal nervous systems resolve sensory conflict for the control of movement. For example, the glass knifefish, Eigenmannia virescens, relies on visual and electrosensory feedback as it swims to maintain position within a moving refuge. To study how signals from these two parallel sensory streams are used in refuge tracking, we constructed a novel augmented reality apparatus that enables the independent manipulation of visual and electrosensory cues to freely swimming fish (n ¼ 5). We evaluated the linearity of multisensory integration, the change to the relative perceptual weights given to vision and electrosense in relation to sensory salience, and the effect of the magnitude of sensory conflict on sensorimotor gain. First, we found that tracking behaviour obeys superposition of the sensory inputs, suggesting linear sensorimotor integration. In addition, fish rely more on vision when electrosensory salience is reduced, suggesting that fish dynamically alter sensorimotor gains in a manner consistent with Bayesian integration. However, the magnitude of sensory conflict did not significantly affect sensorimotor gain. These studies lay the theoretical and experimental groundwork for future work investigating multisensory control of locomotion.
Minimally invasive treatment of vascular disease demands dynamic navigation through complex blood vessel pathways and accurate placement of an interventional device, which has resulted in increased reliance on fluoroscopic guidance and commensurate radiation exposure to the patient and staff. Here we introduce a guidance system inspired by electric fish that incorporates measurements from a newly designed electrogenic sensory catheter with preoperative imaging to provide continuous feedback to guide vascular procedures without additional contrast injection, radiation, image registration, or external tracking. Electrodes near the catheter tip simultaneously create a weak electric field and measure the impedance, which changes with the internal geometry of the vessel as the catheter advances through the vasculature. the impedance time series is then mapped to a preoperative vessel model to determine the relative position of the catheter within the vessel tree. We present navigation in a synthetic vessel tree based on our mapping technique. experiments in a porcine model demonstrated the sensor's ability to detect cross-sectional area variation in vivo. these initial results demonstrate the capability and potential of this novel bioimpedance-based navigation technology as a non-fluoroscopic technique to augment existing imaging methods. clinical Motivation The number of vascular procedures performed under fluoroscopic guidance is increasing as minimally invasive techniques are developed for the diagnosis and treatment of a widening array of vascular diseases 1,2. With the reliance on fluoroscopic imaging for device guidance and navigation comes increased radiation dose to the patient 3 and interventional staff 4-6. Furthermore, these complicated endovascular procedures require dynamic navigation and accurate positioning of interventional devices relative to the vascular tree, which can be extremely challenging with only two-dimensional fluoroscopic images (see Supplementary Material for example case). As a result, multiple contrast agent injections, image acquisitions, and catheter exchanges are often necessary. There are existing techniques to reduce radiation use during endovascular procedures. Systems such as CARTO 3 (Biosense Webster, Diamond Bar, CA) and Rhythmia (Boston Scientific, Marlborough, MA) employ external electromagnetic or external electric sources on the outside of the body to localize catheters in the cardiac chamber. These technologies have revolutionized electroanatomic mapping of the heart and reduced radiation exposure during cardiac electrophysiology procedures 7-10 but are currently unsuitable for catheter navigation through the vessel tree. In fact, the catheters are usually navigated from the femoral artery using fluoroscopic guidance, because the sensing volume created by the external sources is limited. The accuracy of the position estimate is greatly diminished in the presence of patient movement, vessel deformation, and unstable heartbeats 11,12. Additionally, these techniques require s...
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