1 / 34

exam 1 CH6: flight in locusts locust flight flight system sensory integration during flight

PART 3: MOTOR STRATEGIES #13: FLIGHT IN LOCUSTS I. exam 1 CH6: flight in locusts locust flight flight system sensory integration during flight summary. LOCUST FLIGHT. locusts can sustain flight for hours  100s of miles phytophageous – eat living plants

noura
Download Presentation

exam 1 CH6: flight in locusts locust flight flight system sensory integration during flight

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. PART 3: MOTOR STRATEGIES #13: FLIGHT IN LOCUSTS I • exam 1 • CH6: flight in locusts • locust flight • flight system • sensory integration during flight • summary

  2. LOCUST FLIGHT • locusts can sustain flight for hours  100s of miles • phytophageous – eat living plants • travel in swarms & strip vegetation • order: Orthoptera • family: Acrididae • > 1200 spp. • research: large tropical / subtr. spp. • Schistocerca gregaria* • Locusta migratoria

  3. LOCUST FLIGHT • 2 main problems associated with locust flight • coordinated rhythmic wing beat • course control

  4. BEHAVIOR • tethered locust flight • triggered by wind (receptors on head)... later • measure everything... to study flight motor behavior • lift • body position • wing position • muscle recording

  5. BEHAVIOR • tethered fly flight

  6. ANATOMY • 2 prs of wings... • 2 sets of flight muscles... • 2nd & 3rd thoracic segments

  7. BEHAVIOR • wing beat stable • ~ 20 Hz, cycle 50 ms • ~ 7 ms out of phase • hindwing > forewing

  8. BEHAVIOR • complex pattern • up (elevation) & down (depression) • back & forth  pronate • can vary angle of attack rather than wing beat

  9. ANATOMY • 10 muscle prs / wing • 4 depressors... activated at top of stroke • 6 elevators... activated at bottom of stroke • hind 1st ... fore 2nd • subtle timing differences • cuticle flexibility important

  10. FLIGHT SYSTEM • Schistocerca gregariaCNS • brain • S1-3 • T1-3 • A1-11

  11. FLIGHT SYSTEM • Schistocerca gregariaCNS • brain • S1-3 • T1-3 • A1-11

  12. FLIGHT SYSTEM • Schistocerca gregariaCNS... flight-relevant bits... • brain • S1-3 • T1-3 • pro • meso • meta • A1-11

  13. FLIGHT SYSTEM • Schistocerca gregariaCNS... flight-relevant bits... • brain • S1-3 • T1-3 • pro • meso • meta • A1-11

  14. FLIGHT SYSTEM • 1 – 5 motor neurons drive each muscle •  10 muscles / wing • ~ few neurons

  15. CENTRAL PATTERN GENERATOR • old idea... sensory input leads to motor output (eg, reflexes such as knee-jerk) • if so... how does rhythmic behavior occur (eg ,flight)? • proprioceptive feedback to CNS: • information about internal state • monitored by receptors (eg, posture in humans)

  16. CENTRAL PATTERN GENERATOR • proprioception in rhythmic movement • triggered by preceding component of movement • eg, backward swing of leg (R2)  proprioceptive sensory signal (S1)  forward swing (R1)... etc • chain reflex or peripheral-control hypotheses: • sensory feedback critical for rhythmic behavior

  17. CENTRAL PATTERN GENERATOR • proprioception in locust flight ? • 3 classes of proprioceptors • wing hinge stretch receptors:  wing  • tegula:  wing  • campaniform sensilla: on wing veins,  by force of lift as wing 

  18. CENTRAL PATTERN GENERATOR • proprioception in locust flight ? • sufficient receptors to explain chain reflex mechanism for flight • once triggered, keeps going because of proprioception • does this happen?

  19. CENTRAL PATTERN GENERATOR • proprioception in locust flight ? • cut sensory nerves between wings & thorax (deafferentation).. • tethered flight • air to head • normal flight pattern • ½ frequency (10 Hz) • some form of central pattern generator in CNS

  20. CENTRAL PATTERN GENERATOR • proprioception in locust flight ? • cut sensory nerves between wings & thorax (deafferentation) • later showed normal • muscle action potentials • CNS motor neuron output • stimulation of sensory nerves  wing beat freq  normal • not ~ phase !

  21. CENTRAL PATTERN GENERATOR • conclusions: proprioceptive feedback... • modulates average activity level of central pattern generator • not needed for basic pattern

  22. CELLULAR ORGANIZATION • small # of motor neurons for each muscle... •  measure EMG of muscles to estimate action potentials of innervating neurons • recordings with 14 electrodes in flight muscles during flight • revealed fundamental features of normal flight

  23. CELLULAR ORGANIZATION • features of normal flight: • elevators & depressors of wing activated by alternating 20 Hz bursts • elevators & depressors of opposing wings synchronous • hindwing depressors active ~ 5 ms before forewing • ~ motor neurons

  24. CELLULAR ORGANIZATION • is a neuron part of the pattern generator?... test with reset experiment... • if YES... depolarizing neuron (injecting current) should rest rhythm of behavior / muscle contraction • if NO... may only receive signals from pattern generator

  25. CELLULAR ORGANIZATION • conducted reset experiment with ~ 80 motor neurons • none showed reset...  not pattern generator • fig. 6.10a shows normal • firing of motor neurons (top) • recordings from muscles (bottom)

  26. CELLULAR ORGANIZATION • what about interneurons? • 3 goals achieved: • reset experiments • inject current & record from other neurons • fill with dye to follow patterns of innervation

  27. CELLULAR ORGANIZATION • what about interneurons? • bilateral pairs in thoracic ganglia • extensive branching... as might be expected ~ motor control

  28. CELLULAR ORGANIZATION • reset experiment with interneurons... • several showed reset...  pattern generator ! • fig. 6.10b shows normal • phasic firing of interneurons (IN301 & IN511) • recordings from muscles (M112)

  29. CELLULAR ORGANIZATION • reset experiment with interneurons... • several showed reset...  pattern generator ! • fig. 6.10b shows normal • phasic firing of interneurons (top) • recordings from muscles (bottom) • further studies showed flight rhythm from excitatory & inhibitory activity within the network  motor neurons

  30. CELLULAR ORGANIZATION • rhythm from excitatory & inhibitory activity within the network  motor neurons • IN504 EPSP  IN301 • IN301 IPSP  IN511 • IN301 EPSP*  IN501 • IN501 IPSP  IN301 • delay suggests additional intercalating interneuron

  31. CELLULAR ORGANIZATION • connectivity among flight interneurons complex • how do circuits  rhythmic output ? • focus on simple part of circuit • IN301 fires... excites IN501 • IN501 fires... inhibits IN301 • delay • something excites IN301 • oscillatory properties

  32. CELLULAR ORGANIZATION • reset of IN501... part of the pattern generator ? • depolarization • shifts IN501 spiking • shifts muscle activity

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

  34. BREAK

More Related