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CH6: flight in locusts locust flight flight system sensory integration during flight summary

PART 3: MOTOR STRATEGIES #14: FLIGHT IN LOCUSTS II. CH6: flight in locusts locust flight flight system sensory integration during flight summary. PART 3: MOTOR STRATEGIES #14: FLIGHT IN LOCUSTS II. CH6: flight in locusts locust flight flight system

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CH6: flight in locusts locust flight flight system sensory integration during flight summary

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  1. PART 3: MOTOR STRATEGIES #14: FLIGHT IN LOCUSTS II • CH6: flight in locusts • locust flight • flight system • sensory integration during flight • summary

  2. PART 3: MOTOR STRATEGIES #14: FLIGHT IN LOCUSTS II • CH6: flight in locusts • locust flight • flight system • sensory integration during flight • summary

  3. CELLULAR ORGANIZATION • IN301 & IN501... 2 of the known parts of the pattern generator

  4. PROPRIOCEPTIVE FEEDBACK • how does proprioceptive feedback work ? ... so far... • it can influence average pattern frequency • it has no “essential” role in pattern generation • experiment... • wingbeat imposed on 1 forewing • how does sensory feedback from this wing influence flight rhythm of the other 3 wings ? • observed that wings phase lock to imposed frequencies...  proprioception does CPG

  5. PROPRIOCEPTIVE FEEDBACK • what are the roles of the 3 types of receptors ? • synaptic connections  CPG interneurons • stimulate wing hinge receptor  fires wing depressor neuron •  inhibits elevator • stimulate campaniform  opposite effect •  proprioceptors can initiate & maintain flight rhythm

  6. PROPRIOCEPTIVE FEEDBACK • tegulae ?... • neurons in phase with elevator motor neurons • neurons excite IN566 • IN566 excites elevator motor neuron

  7. PROPRIOCEPTIVE FEEDBACK • tegulae ?... • stimulation of afferent neurons resets flight rhythm

  8. PROPRIOCEPTIVE FEEDBACK •  wing proprioceptors are elements of the CPG: • phasically active ~ wingbeat cycle • activation  initiate, entrain & maintain oscillation • deafferentation  reduces operation of CPG • reset CPG when stimulated

  9. PROPRIOCEPTIVE FEEDBACK • how do wing proprioceptors  flight... 2 main inputs • wing depression  excites tegulae  • excites elevator motor neurons • wing elevation  excites wing hinge stretch  • excites depressor motor neurons • inhibits wing elevator motor neurons

  10. PROPRIOCEPTIVE FEEDBACK • why is CPG control so complicated ? • stable core oscillating circuit, and • sensitive to sensory  appropriate to situation • central rhythm generator integrated with sensory  normal flight pattern

  11. SENSORY INTEGRATION DURING FLIGHT • course control ? • must make rapid steering adjustment ~ wind

  12. SENSORY INTEGRATION DURING FLIGHT • uses 3 different sensory systems... exteroceptors • compound eyes • ocelli (simple eyes) • wind-sensitive hairs

  13. simple • ~ fast SENSORY INTEGRATION DURING FLIGHT • uses 3 different sensory systems... exteroceptors • compound eyes... 3D but • complex • ~ slow (100 ms  thorax ~ 2 wingbeat cycles) • ocelli (simple eyes) • wind-sensitive hairs

  14. SENSORY INTEGRATION DURING FLIGHT • uses 3 different sensory systems... exteroceptors • compound eyes... 3D but complex & slow • ocelli (simple eyes)... pitch & roll, fast • wind-sensitive hairs... yaw & pitch, fast

  15. SENSORY INTEGRATION DURING FLIGHT • uses 3 different sensory systems... exteroceptors • compound eyes... 3D but complex & slow • ocelli (simple eyes)... pitch & roll, fast • wind-sensitive hairs... yaw & pitch, fast • 2 sensorimotor pathways • slow  head position, steering by legs & abdomen

  16. SENSORY INTEGRATION DURING FLIGHT • uses 3 different sensory systems... exteroceptors • compound eyes... 3D but complex & slow • ocelli (simple eyes)... pitch & roll, fast • wind-sensitive hairs... yaw & pitch, fast • 2 sensorimotor pathways • slow  head position, steering by legs & abdomen • fast  thorax, course deviation information

  17. DEVIATION-DETECTING INTERNEURONS • ocelli (simple eyes)... detect horizon deviation • 3 pairs of deviation-detecting neurons (DDNs) • DNI – ipsilateral ocellus • DNM – medial ocellus • DNC – contralateral ocellus

  18. DEVIATION-DETECTING INTERNEURONS • ocelli (simple eyes)... detect horizon deviation • 3 pairs of deviation-detecting neurons (DDNs) • DNI – ipsilateral ocellus • DNM – medial ocellus • DNC – contralateral ocellus • respond to different deviations ~ movement detectors*

  19. DEVIATION-DETECTING INTERNEURONS • ocelli (simple eyes)... detect horizon deviation • 3 pairs of deviation-detecting neurons (DDNs) • DNI – ipsilateral ocellus • DNM – medial ocellus • DNC – contralateral ocellus • respond to different deviations ~ movement detectors* • relay to thoracic ganglia

  20. DEVIATION-DETECTING INTERNEURONS • ocelli (simple eyes)... detect horizon deviation • 3 pairs of deviation-detecting neurons • DNC – contralateral ocellus* • relay to thoracic ganglia • integrated with • air current stimuli  hairs • visual stimuli  eyes

  21. DEVIATION-DETECTING INTERNEURONS • ocelli (simple eyes)... detect horizon deviation • 3 pairs of deviation-detecting neurons (DDNs) • respond to different deviations ~ movement detectors* • integrated with air current stimulus to hairs* and eyes • hair signals  ocelli signals

  22. DEVIATION-DETECTING INTERNEURONS • ocelli (simple eyes)... detect horizon deviation • 3 pairs of deviation-detecting neurons (DDNs) • respond to different deviations ~ movement detectors * • integrated with air current stimulus to hairs* and eyes • hair signals  ocelli signals • ocelli signals  hair signals • multimodal input critical... feature detector neurons

  23. FLIGHT CONTROL CIRCUITRY • DDNs integrated into thoracic circuitry via thoracic interneurons (TINs) • only works during flight • influenced by the CPG • phase-gated = signal at appropriate phase of of cycle  course control • ... but not part of the CPG • TINs integrate sensory with phase-locked CPG

  24. SUMMARY • locusts have 2 pairs of wings @ thorax • beat @ 20 Hz, 7 ms offset cycles • 10 pairs of muscles / wing: 4 depressors, 6 elevators • driven by 1-5 neurons / muscle • isolated thoracic circuitry  rhythmic motor output • central pattern generator... influenced by proprioceptive sensory feedback • 3 types of sensilla: wing hinge, tegula, campaniform • activation  rhythmic motor output,  part of CPG • CPG = central oscillating core + sensory feedback

  25. SUMMARY • CPG = central oscillating core + sensory feedback • 3 primary exteroceptor types on head  flight • activate descending neurons, deviation-detecting neurons (DDNs) are 1 type • multimodal DDNs detect flight deviations • DDNs  thoracic interneurons (TINs) • TIN  motor neurons via interneurons • tonic sensory signal  phasic signal by CPG gating •  course control during flight •  CPG  rhythms (1) wingbeat & (2) sensory signal

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