Behavioral resilience via dynamic circuit firing homeostasis

Area of Science:

• Neuroscience
• Motor Control
• Homeostatic Regulation

Background:

• Stable neural circuit output is crucial for consistent function.
• Homeostatic mechanisms are essential for adapting to perturbations.
• Synaptic plasticity plays a key role in neural circuit regulation.

Purpose of the Study:

• To investigate compensatory mechanisms in Drosophila larvae motor circuits.
• To determine the impact of synaptic weakening on locomotion.
• To identify the specific motor neuron types involved in compensation.

Main Methods:

• Perturbation of presynaptic transmitter release and postsynaptic glutamate receptors.
• In vivo imaging of motor neuron activity.
• Analysis of synaptic input selectivity in motor neurons.

Main Results:

• Synaptic weakening had minimal impact on locomotion, suggesting compensation.
• Five forms of synaptic weakening increased motor neuron activity bout duration.
• Compensation was input-selective, occurring in tonic type Ib MNs but not phasic type Is MNs.
• Inhibitory central pre-motor neuron activity decreased, specifically targeting tonic inputs.

Conclusions:

• Motor neuron firing is dynamically regulated by cell-autonomous excitability adjustments and circuit-level inhibitory drive.
• Homeostatic compensation maintains tonic motor drive while preserving phasic drive for locomotion.
• Input selectivity of compensation highlights differential regulation of motor neuron types.