Delayed axonal pruning in the ant brain: a study of developmental trajectories

Area of Science:

• Neuroscience
• Developmental Biology
• Animal Behavior

Background:

• Neuronal maturation and behavioral development are crucial for survival.
• Axonal pruning, the elimination of excessive neuronal connections, is a common developmental process.
• In Drosophila, axonal pruning primarily occurs during metamorphosis.

Purpose of the Study:

• To investigate the timing and characteristics of axonal pruning in the ant Cataglyphis albicans.
• To explore the relationship between axonal pruning, brain region development, and behavioral ecology.
• To determine if adult ants exhibit neotenous brain characteristics allowing for environmental adaptation.

Main Methods:

• Electron microscopy (EM)-serial sectioning and 3D-reconstructions were employed.
• Analysis focused on the mushroom bodies, specifically the lip and collar regions.
• Developmental rates of brain components were correlated with behavioral ecology.

Main Results:

• Axonal pruning in Cataglyphis albicans occurs gradually over 60 days after eclosion, not during metamorphosis.
• Pruning rates differ between brain regions; the collar region (visual integrator) shows delayed pruning, linked to visual experience.
• Differential development rates within a neuropil correlate with the ants' behavioral ecology, suggesting glial involvement in pruning.

Conclusions:

• Adult ants possess relatively neotenous brains, enabling neuronal plasticity and adaptation to environmental demands.
• This neoteny may underlie age-dependent division of labor and the remarkable behavioral flexibility observed in ants.
• Axonal pruning timing is influenced by specific sensory experiences and ecological pressures.