Pulmonary vagal modulation of ventilation in toads (Bufo marinus)

Reid, Scott D.; Milsom, William K.; Meier, Janice T.; Munns, Suzanne L.; West, Nigel H.

doi:10.1016/s0034-5687(99)00118-8

Cited by 21 publications

(5 citation statements)

References 27 publications

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“…4d). The respiration data show that the cane toad has an irregular respiration pattern-intermittent or discontinuous breathing patterns (Supplementary Section X) are common in amphibians [50][51][52] -which agrees with both the radar and camera-based results.…”

Section: Articlesupporting

confidence: 75%

“…The cane toad has a radar cross-section (the buccal area, ~2 × 2.5 cm 2 ) that is smaller than the human chest, making the experiment more challenging than human trials. The buccal cavity is connected to the lungs during its breathing activity [50][51][52] . The toad was located ~1 m from the radar antenna, with the beam pointing to the toad's buccal area.…”

Section: Articlementioning

confidence: 99%

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Photonic radar for contactless vital sign detection

Zhang

Liu

Stephens³

et al. 2023

Nat. Photon.

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Vital sign detection is used across ubiquitous scenarios in medical and health settings, and contact and wearable sensors have been widely deployed. However, they are unsuitable for patients with burn wounds or infants with insufficient areas for attachment. Contactless detection can be achieved using camera imaging, but it is susceptible to ambient light conditions and has privacy concerns. Here we report a photonic radar for non-contact vital sign detection to overcome these challenges. This photonic radar can achieve millimetre-level range resolution based on synthesized radar signals with a bandwidth of up to 30 GHz. The high resolution of the radar system enables accurate respiratory detection from breathing simulators and a cane toad as a human proxy. Moreover, we demonstrate that the optical signals generated from the proposed system can enable vital sign detection based on light detection and ranging (LiDAR). This demonstration reveals the potential of a sensor-fusion architecture that can combine the complementary features of radar and LiDAR to achieve improved sensing accuracy and system resilience. The work provides a technical basis for contactless and high-resolution vital sign detection to meet the increasing demands of future medical and healthcare applications.

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Section: Articlesupporting

confidence: 75%

Section: Articlementioning

confidence: 99%

Photonic radar for contactless vital sign detection

Zhang

Liu

Stephens³

et al. 2023

Nat. Photon.

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“…Factors that modulate episodic breathing in ectothermic vertebrates include peripheral chemo-and mechanosensory afferent inputs (34,36,37,53,54), descending inputs from rostral brain structures (34,47,52) and mechanisms intrinsic to the brain stem (55,58). In this study, transection of the caudal turtle spinal cord significantly increased singlet breathing and attenuated the number of breaths/ episode when challenged with hypercapnia.…”

Section: Reduced Episodic Breathing In Spinalized Turtles: Potential mentioning

confidence: 60%

Spinal cord injury-induced changes in breathing are not due to supraspinal plasticity in turtles (Pseudemys scripta)

Johnson¹,

Creighton²

2005

American Journal of Physiology-Regulatory, Integrative and Comp

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Johnson, Stephen M., and Robert J. Creighton. Spinal cord injury-induced changes in breathing are not due to supraspinal plasticity in turtles (Pseudemys scripta). Am J Physiol Regul Integr Comp Physiol 289: R1550 -R1561, 2005. First published August 11, 2005; doi:10.1152/ajpregu.00397.2005-After occurrence of spinal cord injury, it is not known whether the respiratory rhythm generator undergoes plasticity to compensate for respiratory insufficiency. To test this hypothesis, respiratory variables were measured in adult semiaquatic turtles using a pneumotachograph attached to a breathing chamber on a water-filled tank. Turtles breathed room air (2 h) before being challenged with two consecutive 2-h bouts of hypercapnia (2 and 6% CO 2 or 4 and 8% CO2). Turtles were spinalized at dorsal segments D8-D10 so that only pectoral girdle movement was used for breathing. Measurements were repeated at 4 and 8 wk postinjury. For turtles breathing room air, breathing frequency, tidal volume, and ventilation were not altered by spinalization; single-breath (singlet) frequency increased sevenfold. Spinalized turtles breathing 6 -8% CO 2 had lower ventilation due to decreased frequency and tidal volume, episodic breathing (breaths/episode) was reduced, and singlet breathing was increased sevenfold. Respiratory variables in sham-operated turtles were unaltered by surgery. Isolated brain stems from control, spinalized, and sham turtles produced similar respiratory motor output and responded the same to increased bath pH. Thus spinalized turtles compensated for pelvic girdle loss while breathing room air but were unable to compensate during hypercapnic challenges. Because isolated brain stems from control and spinalized turtles had similar respiratory motor output and chemosensitivity, breathing changes in spinalized turtles in vivo were probably not due to plasticity within the respiratory rhythm generator. Instead, caudal spinal cord damage probably disrupts spinobulbar pathways that are necessary for normal breathing.control of breathing; respiration; reptile; chelonian; episodic breathing IN RESPONSE TO INJURY, THE central nervous system undergoes morphological and physiological changes to compensate for loss of function, such as altered gene expression, neuronal reorganization, and altered synaptic plasticity. Likewise, after incomplete spinal cord injury, remaining descending spinal pathways and spinal motor networks undergo reorganization and neuroplasticity to compensate for loss of function (6,20,51). Because respiratory dysfunction is the leading cause of death in spinal cord-injured patients (9, 59), understanding the mechanisms by which the respiratory control system undergoes compensatory plasticity may lead to novel therapeutic strategies for reducing respiratory complications and subsequent morbidity.After spinal cord injury, breathing pattern is altered to maintain adequate ventilation (V E). For example, high cervical spinal cord injury compromises synaptic drive to phrenic and intercostal motoneurons in mammals, r...

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“…Chemosensory feedback has been suggested to play a role in the modulation of the episodic breathing pattern in the decerebrate, unidirectionally ventilated toad Bufo marinus, since bilateral vagotomy prevents hypercapnia-induced increases in breathing episodes (Reid et al, 2000). Because our preparation was devoid of feedback from peripheral oxygensensitive chemoreceptors, the data in this study argue that brainstem hypoxia is capable of stimulating episodic breathing in the bullfrog brainstem.…”

Section: Hypoxia-induced Changes In Respiratory Pattern Generationmentioning

confidence: 77%

Development of the respiratory response to hypoxia in the isolated brainstem of the bullfrogRana catesbeiana

Winmill

Chen

Hedrick

2005

Journal of Experimental Biology

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SUMMARY The aim of this study was to examine the effects of cellular hypoxia, and the contribution of anaerobic metabolism, on respiratory activity in bullfrogs at different stages of development. Respiratory-related neural activity was recorded from cranial nerve rootlets in isolated brainstem preparations from pre-metamorphic (Taylor–Köllros (T-K) stages VIII-XVI) and postmetamorphic tadpoles (T-K stages XXIV-XXV) and adults. Changes in fictive gill/lung activity in brainstems from pre-metamorphic tadpoles and lung activity in postmetamorphic tadpoles and adults were examined during superfusion with control (98% O2/2% CO2) or hypoxic (98%N2/2% CO2) artificial cerebrospinal fluid (aCSF). Iodoacetate (IAA; 100 μmol l–1) was used in conjunction with hypoxic aCSF to inhibit glycolysis. Gill burst frequency in pre-metamorphic brainstems did not change over a 3 h exposure to hypoxia and fictive lung burst frequency slowed significantly, but only after 3 h hypoxia. Blockade of glycolysis with IAA during hypoxia significantly reduced the time respiratory activity could be maintained in pre-metamorphic, but not in adult,brainstems. In brainstems from post-metamorphic tadpoles and adults, lung burst frequency became significantly more episodic within 5–15 min hypoxic exposure, but respiratory neural activity was subsequently abolished in every preparation. The cessation of fictive breathing was restored to control levels upon reoxygenation. Neither tadpole nor adult brainstems exhibited changes in neural bursts resembling `gasping' that is observed in mammalian brainstems exposed to severe hypoxia. There was also a significant increase in the frequency of `non-respiratory' bursts in hypoxic postmetamorphic and adult brainstems, but not in pre-metamorphic brainstems. These results indicate that pre-metamorphic tadpoles are capable of maintaining respiratory activity for 3 h or more during severe hypoxia and rely to a great extent upon anaerobic metabolism to maintain respiratory motor output. Upon metamorphosis, however, hypoxia results in significant changes in respiratory frequency and pattern, including increased lung burst episodes,non-ventilatory bursts and a reversible cessation of respiratory activity. Adults have little or no ability to maintain respiratory activity through glycolysis but, instead, stop respiratory activity until oxygen is available. This `switch' in the respiratory response to hypoxia coincides morphologically with the loss of gills and obligate air-breathing in the postmetamorphic frog. We hypothesize that the cessation of respiratory activity in post-metamorphic tadpoles and adults is an adaptive, energy-saving response to low oxygen.

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Pulmonary vagal modulation of ventilation in toads (Bufo marinus)

Cited by 21 publications

References 27 publications

Photonic radar for contactless vital sign detection

Photonic radar for contactless vital sign detection

Spinal cord injury-induced changes in breathing are not due to supraspinal plasticity in turtles (Pseudemys scripta)

Development of the respiratory response to hypoxia in the isolated brainstem of the bullfrogRana catesbeiana

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