Insect motor control: circuitry and unnderlying behaviour Flashcards
Process of jumping is partly…
Muscular and storage of energy in a spring - part of cuticle sits on top of the femur
How is the tibia ‘activated’ for jumping?
(2 marks)
- Cuticle is distorted and stores energy in semilunar process
- Can be released as leg extended and greatly increase force that can be generated
How do humans store and release energy in the foot?
(3 marks)
- Energy stored in achilles tendon or sole of foot
- There’s a longitudinal arch and tendons run along it foot flattened, and tendons stretched
- Energy released when walking
What are the two muscle groups used in insect movement (jumping)?
(2 mark)
Extensor tibiae muscle
Flexor muscle
What are the different types of neurons present in the extensor tibiae muscle?
- Fast extensor tibiae (FETi) - used for jumping, kicking
- Inhibitory neuron
- Slow extensor tibiae (SETi) - for walking and not jumping
- Modulatory DUM Eti motor neuron
Where do neurons from the visual system go and how does this transmission initiate movement?
(5 marks)
- Metathoracic ganglia
- From ^ info goes to descending contralalteral movement detectors (DCMDs)
- DCMD actvates a neuron that initiates the jump - so one leg flexed but cuticular spring put under tension
- Causes activation of cocking neuron
- Cocking neuron activates FETi and flexor motor neuron
Outline the structure of the cocking mechanism?
(5 marks)
- DCMD sends an axon down into the sub-eosophageal ganglion
- Axon then goes down inot thoracic ganglia - few branch into mesothoracic but main branch is in metathoracic
- FETi neuron and flexor tibiae neuron are in metathoracic ganglion
- Cocking neuron receive input from DCMD and its cell body branches into meso and meta thoracic ganglion
- DCMD synapse with C neuron in mesothroacic g and axon goes down to meta g which co-activates flexor and extensor motor neurons
How do we know the connection between teh c neuron and FETi is monsynaptic?
- Get spike in c neuron and have short latency before getting epsp in FETi
What happens everytime there’s an action potential in the extensor motor neuron?
See epsps in the flexor (short latency period indicates its monosynaptic)
How does the image below show a monosynaptic connection?
(3 marks)
- Bend in the main neurite coming out of cell body of fast extensor
- main branch coming out of cell body of flexor motor neuron
- Extensor motor neuron is much darker
Why does the campaniform sinsillae buckel when cuticle is put under strain?
(3 marks)
- Under campaniform sinsillae are pits with sensory neurons
- Dendrites which respond and send signals into ganglion
- Both go directly into FETi motor neuorn and the flexor motor neuron is depolarised
What happens after campaniform sinsillae buckles?
(3 marks)
- Cuticle is distorted and causes gradual rise of FETi motor neuron till it reaches spike threshold
- Causing spike
- Flexors receive direct input from campaniform sinsillae
How is energy released after being stored in the cuticular spring?
(5 marks)
- M neuron contributes to flexor inhibtion that triggers jump
- Input from extensor no longer sufficient to cause AP
- Common inhibitor motor neuron inhibits the flexor muscle to relax
- M neuron cell body is in metathoracic ganglion
- AP in M neuron gets short latency and then ipsp in flexor mn
What kind of stimlulus in DCMD causes an action potential?
Visual stimulus
Where does an action potential in DCMD cause another action potential to happen?
(4 marks)
- Causes an action potential in M neuron
- in later ones thre is no action potentials on epsps
- If get spike in m neuron get release of transmitter onto flexor motor neuron
- This is a monosynaptic connection
