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

IN301 & IN501... 2 of the known parts of the pattern generator

CELLULAR ORGANIZATION

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 wingdepressor neuron

inhibits elevator

stimulate campaniform opposite effect

proprioceptors can initiate & maintain flight rhythm

PROPRIOCEPTIVE FEEDBACK

tegulae ?... neurons in phase

with elevatormotor neurons

neurons excite IN566

IN566 exciteselevator motorneuron

PROPRIOCEPTIVE FEEDBACK

tegulae ?... stimulation of afferent neurons resets flight rhythm

PROPRIOCEPTIVE FEEDBACK

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

how do wing proprioceptors flight... 2 main inputs

1. wing depression excites tegulae

excites elevator motor neurons

2. wing elevation excites wing hinge stretch

excites depressor motor neurons

inhibits wing elevator motor neurons

PROPRIOCEPTIVE FEEDBACK

why is CPG control so complicated ?

1. stable core oscillating circuit, and

2. sensitive to sensory appropriate to situation

central rhythm generator integrated with sensory

normal flight pattern

PROPRIOCEPTIVE FEEDBACK

course control ?

must make rapid steering adjustment ~ wind

SENSORY INTEGRATION DURING FLIGHT

uses 3 different sensory systems... exteroceptors

1. compound eyes

2. ocelli (simple eyes)

3. wind-sensitive hairs

SENSORY INTEGRATION DURING FLIGHT

uses 3 different sensory systems... exteroceptors

1. compound eyes... 3D but

complex

~ slow (100 ms thorax ~ 2 wingbeat cycles)

2. ocelli (simple eyes)

3. wind-sensitive hairs simple

~ fast

SENSORY INTEGRATION DURING FLIGHT

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

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

2 sensorimotor pathways

1. slow head position,

steering by legs & abdomen

SENSORY INTEGRATION DURING FLIGHT

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

2 sensorimotor pathways

1. slow head position, steering by legs & abdomen

2. fast thorax, course deviation information

SENSORY INTEGRATION DURING FLIGHT

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

DEVIATION-DETECTING INTERNEURONS

DDNs integrated into thoracic circuitry via thoracic interneurons (TINs) only works during flight influenced by the CPG

phase-gated = signal atappropriate phase ofof cycle course control

... but not part of the CPG TINs integrate sensory

with phase-locked CPG

FLIGHT CONTROL CIRCUITRY

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

SUMMARY