A cephalothoracic command system controls stridulation in the acridid grasshopper Omocestus viridulus L

Area of Science:

• Neuroethology
• Insect Behavior
• Motor Control

Background:

• Stridulation in acridid grasshoppers is a complex behavior crucial for communication.
• The neural circuits controlling stridulation are not fully understood.
• Descending brain neurons play a key role in coordinating motor outputs.

Purpose of the Study:

• To identify and characterize descending brain neurons involved in stridulation in Omocestus viridulus.
• To determine if these neurons are sufficient and necessary for initiating and controlling stridulatory movements.
• To investigate the role of these neurons in modulating stridulatory behavior.

Main Methods:

• Simultaneous intracellular recording and stimulation of descending brain neurons with hindleg movement recording in a minimally dissected grasshopper preparation.
• Identification of B-DC-3 interneurons using intracellular staining.
• Depolarization and inhibition techniques to assess neuronal function.

Main Results:

• Descending B-DC-3 interneurons were identified with medial soma and dendritic arborization in the protocerebrum, with axons descending contralaterally.
• Stridulatory behavior was strictly coupled with tonic spike activity in B-DC-3 interneurons (approx. 100 Hz).
• Individual B-DC-3 interneurons were sufficient to initiate and maintain stridulation, and necessary for its generation; their stimulation modulated repetition rate and amplitude.

Conclusions:

• B-DC-3 interneurons function as the command system for stridulation in Omocestus viridulus.
• These neurons initiate, maintain, and modulate species-specific stridulatory leg movements.
• The findings provide insight into the neural basis of complex motor behaviors in insects.