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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 - PowerPoint PPT Presentation
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exam 1 CH6: flight in locusts
locust flight flight system sensory integration during flight summary
PART 3: MOTOR STRATEGIES#13: FLIGHT IN LOCUSTS I
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
LOCUST FLIGHT
2 main problems associated with locust flight coordinated rhythmic wing beat course control
LOCUST FLIGHT
tethered locust flight triggered by wind (receptors on head)... later measure everything... to study flight motor behavior
lift body position wing position muscle recording
BEHAVIOR
tethered fly flight
BEHAVIOR
2 prs of wings... 2 sets of flight muscles... 2nd & 3rd thoracic segments
ANATOMY
wing beat stable
~ 20 Hz, cycle 50 ms
~ 7 ms out of phase
hindwing > forewing
BEHAVIOR
complex pattern
up (elevation) & down
(depression)
back & forth pronate
can vary angle of attack
rather than wing beat
BEHAVIOR
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
ANATOMY
Schistocerca gregaria CNS brain S1-3 T1-3 A1-11
FLIGHT SYSTEM
Schistocerca gregaria CNS brain S1-3 T1-3 A1-11
FLIGHT SYSTEM
Schistocerca gregaria CNS... flight-relevant bits... brain S1-3 T1-3
pro meso meta
A1-11
FLIGHT SYSTEM
Schistocerca gregaria CNS... flight-relevant bits... brain S1-3 T1-3
pro meso meta
A1-11
FLIGHT SYSTEM
1 – 5 motor neurons drive each muscle 10 muscles / wing ~ few neurons
FLIGHT SYSTEM
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)
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
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
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?
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
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 !
CENTRAL PATTERN GENERATOR
conclusions: proprioceptive feedback...
modulates average activity level of central
pattern generator
not needed for basic pattern
CENTRAL PATTERN GENERATOR
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
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
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 onlyreceive signals from pattern generator
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)
CELLULAR ORGANIZATION
what about interneurons? 3 goals achieved:
reset experiments inject current & record
from other neurons fill with dye to follow
patterns of innervation
CELLULAR ORGANIZATION
what about interneurons?
bilateral pairs in thoracic ganglia
extensive branching...
as might be expected
~ motor control
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)
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
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
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
CELLULAR ORGANIZATION
reset of IN501... part of the pattern generator ? depolarization shifts IN501 spiking shifts muscle activity
CELLULAR ORGANIZATION
IN301 & IN501... 2 of the known parts of the pattern generator
CELLULAR ORGANIZATION
BREAK
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