Peripheral neural pathways of nociception in Manduca sexta
Caron, Daniel P.
2020
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The larvae of the fruit fly Drosophila melanogaster, respond to potentially harmful (noxious) stimuli with a rolling escape behavior. This response is mediated by Class IV multi-dendritic neurons which act as nociceptors, sensing noxious thermal and mechanical stimuli. The neural pathways and molecular mechanisms for thermosensation and mechanosensation have been well established in Diptera, but ... read moreit is unknown whether these findings can be generalized to other insect orders. Here, we examine the neural activity of sensory neurons of a Lepidopteran, Manduca sexta, in response to noxious mechanical and thermal stimuli, and attempt to draw connections with known nociceptive systems. This may help uncover basic features of nociception that are conserved across diverse species. The caterpillar of M. sexta responds to noxious thermal or mechanical stimuli with a strike behavior, wherein the animal’s head rapidly moves to the site of stimulation. First, we test whether, as in D. melanogaster, multimodal sensory neurons mediate the response to multiple types of stimuli, or if responsiveness to noxious thermal and mechanical stimuli are mediated by distinct neural circuits. We use extracellular recordings of the dorsal nerve in M. sexta to study the firing of nociceptive neurons and demonstrate that mechanical and thermal stimuli activate the same nociceptive neurons. Then we probe using receptive fields, ablations, and pharmacology to identify these nociceptors. We demonstrate that M. sexta thermal and mechanical nociception is mediated by Class γ multi-dendritic neurons, homologues of known D. melanogaster nociceptors. Together, these findings suggest that multimodal nociception isconserved across insect species.
Advisors: Barry A. Trimmer and Eric D. Tytellread less - ID:
- gm80j790x
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