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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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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 • sensory integration during flight • summary
CELLULAR ORGANIZATION • IN301 & IN501... 2 of the known parts of the pattern generator
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
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
PROPRIOCEPTIVE FEEDBACK • tegulae ?... • neurons in phase with elevator motor neurons • neurons excite IN566 • IN566 excites elevator motor neuron
PROPRIOCEPTIVE FEEDBACK • tegulae ?... • stimulation of afferent neurons resets flight rhythm
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
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
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
SENSORY INTEGRATION DURING FLIGHT • course control ? • must make rapid steering adjustment ~ wind
SENSORY INTEGRATION DURING FLIGHT • uses 3 different sensory systems... exteroceptors • compound eyes • ocelli (simple eyes) • wind-sensitive hairs
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
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
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
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
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
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*
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
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
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
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
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
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
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