Conflicting adaptations in an inhibitory feedback circuit.

Area of Science:

• Neuroscience
• Computational Neuroscience
• Systems Neuroscience

Background:

• Neural networks rely on homeostatic plasticity to maintain stable activity despite perturbations.
• Conflicting homeostatic mechanisms at local and network levels can arise, particularly in inhibitory feedback circuits.

Purpose of the Study:

• To investigate potential conflicts between local and network-level homeostatic plasticity.
• To examine how these conflicting mechanisms affect neural activity stability in the Drosophila mushroom body.

Main Methods:

• Utilized dual-colour calcium imaging in Drosophila.
• Artificially activated excitatory Kenyon cells (KCs) for prolonged periods (24 hours).
• Monitored activity changes in KCs and the anterior paired lateral (APL) neuron.

Main Results:

• Prolonged KC activation led to decreased APL neuron sensitivity to KC activity.
• KCs attempted to compensate for excess activity by reducing excitation.
• Reduced inhibition from APL counteracted KC compensation, hindering expected homeostatic reduction in odour responses.

Conclusions:

• Local neuronal adaptations can counteract broader network-level adaptations.
• Conflicting homeostatic mechanisms can prevent the stabilization of neural activity.
• Demonstrates a novel form of homeostatic conflict in neural circuits.