Introducing the brain: insect flight controls (Introduction)

by David Turell , Tuesday, June 06, 2023, 18:50 (326 days ago) @ David Turell

Uses electric charges across synapses:

https://www.sciencedaily.com/releases/2023/06/230606111652.htm

"The fruit fly Drosophila melanogaster beats its wings around 200 times per second in order to move forward. Other small insects manage even 1,000 wingbeats per second. It is this high frequency of wingbeats that generates the annoying high-pitched buzzing sound we commonly associate with mosquitoes. Every insect has to beat its wings at a certain frequency to not get "stuck" in the air, which acts as a viscous medium due to their small body size. For this purpose, they employ a clever strategy that is widely used in the insect world. This involves reciprocal stretch activation of the antagonistic muscles that raise and depress the wings. The system can oscillate at high frequencies, thus producing the high rate of wingbeats required for propulsion. The motor neurons are unable to keep pace with the speed of the wings so that each neuron generates an electrical pulse that controls the wing muscles only about every 20th wingbeat. These pulses are precisely coordinated with the activity of other neurons. Special activity patterns are generated in the motor neurons that regulate the wingbeat frequency. Each neuron fires at a regular rate but not at the same time as the other neurons. There are fixed intervals between which each of them fires.

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"As a result, they found that the neural network regulating flight is composed of just a small number of neurons that communicate with each other through electrical synapses only.

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"Using experimentation and mathematical modeling, the researchers have been able to show that such a sequential distribution of pulse generation can also occur when neural activity is directly controlled electrically, without the presence of neurotransmitters. The neurons then create a special kind of pulse and 'listen' closely to each other, especially if they have just been active.

"Mathematical analyses predicted that this would not be possible with "normal" pulses. Hence, it would appear unlikely that transmission between neurons in a purely electrical form would result in this sequenced firing pattern. In order to test this theoretical hypothesis experimentally, certain ion channels in the neurons of the network were manipulated. As expected, the activity pattern of the flight circuit became synchronized -- just as the mathematical model had predicted. This experimental manipulation caused significant variations in the power generated during flight. It is thus apparent that the desynchronization of the activity pattern determined by the electrical synapses of the neural circuit is necessary to ensure that the flight muscles are able to generate a consistent power output.

"The findings of the team based in Mainz and Berlin are particularly surprising given that it was previously thought that interconnections by electrical synapses actually result in a synchronized activity of neurons. The activity pattern generated by the electrical synapses detected here indicates that there may well be forms of information processing by the nervous system that are as yet unexplained. The same mechanism may not only play a role in thousands of other insect species but also in the human brain, where the purpose of electrical synapses is still not fully understood. (my bold)

Comment: note my bold. This research may help in understanding our brain's neurons actions in processing information. I was amazed to see how fast insect wings beat and wonder how they handle fatigue, which in human comes from a buildup of Lactic acid from the muscle's metabolism.