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

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

H IN301 & IN of the known parts of the pattern generator CELLULAR ORGANIZATION

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

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

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

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

H  wing proprioceptors are elements of the CPG: 1.phasically active ~ wingbeat cycle 2.activation  initiate, entrain & maintain oscillation 3.deafferentation  reduces operation of CPG 4.reset CPG when stimulated PROPRIOCEPTIVE FEEDBACK

H how do wing proprioceptors  flight... 2 main inputs 1.wing depression  excites tegulae  H excites elevator motor neurons 2.wing elevation  excites wing hinge stretch  H excites depressor motor neurons H inhibits wing elevator motor neurons PROPRIOCEPTIVE FEEDBACK

H why is CPG control so complicated ? 1.stable core oscillating circuit, and 2.sensitive to sensory  appropriate to situation H  central rhythm generator integrated with sensory  normal flight pattern PROPRIOCEPTIVE FEEDBACK

H course control ? H must make rapid steering adjustment ~ wind SENSORY INTEGRATION DURING FLIGHT

H uses 3 different sensory systems... exteroceptors 1.compound eyes 2.ocelli (simple eyes) 3.wind-sensitive hairs SENSORY INTEGRATION DURING FLIGHT

H uses 3 different sensory systems... exteroceptors 1.compound eyes... 3D but H complex H ~ slow (100 ms  thorax ~ 2 wingbeat cycles) 2.ocelli (simple eyes) 3.wind-sensitive hairs H simple H ~ fast SENSORY INTEGRATION DURING FLIGHT

H uses 3 different sensory systems... exteroceptors 1.compound eyes... 3D but complex & slow 2.ocelli (simple eyes)... pitch & roll, fast 3.wind-sensitive hairs... yaw & pitch, fast SENSORY INTEGRATION DURING FLIGHT

H uses 3 different sensory systems... exteroceptors 1.compound eyes... 3D but complex & slow 2.ocelli (simple eyes)... pitch & roll, fast 3.wind-sensitive hairs... yaw & pitch, fast H 2 sensorimotor pathways 1.slow  head position, steering by legs & abdomen SENSORY INTEGRATION DURING FLIGHT

H uses 3 different sensory systems... exteroceptors 1.compound eyes... 3D but complex & slow 2.ocelli (simple eyes)... pitch & roll, fast 3.wind-sensitive hairs... yaw & pitch, fast H 2 sensorimotor pathways 1.slow  head position, steering by legs & abdomen 2.fast  thorax, course deviation information SENSORY INTEGRATION DURING FLIGHT

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

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

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

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

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

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

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

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

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