Scanning laser optical tomography resolves structural plasticity during regeneration in an insect brain.

Area of Science:

• Neuroscience
• Microscopy Techniques
• Insect Model Systems

Background:

• Optical Projection Tomography (OPT) enables 3D imaging of large biological samples beyond confocal microscopy's depth limits.
• Scanning Laser Optical Tomography (SLOTy) enhances OPT by simultaneously detecting fluorescence and absorbance with high sensitivity.
• SLOTy is applied here to study brain plasticity in an insect model.

Purpose of the Study:

• To visualize and quantify volumetric changes in sensory processing centers of the adult locust, Locusta migratoria.
• To investigate the effects of axonal injury and regeneration on olfactory centers.
• To assess the utility of SLOTy for studying brain plasticity.

Main Methods:

• Axotomized olfactory receptor neurons via antennal nerve crushing or antenna ablation in adult locusts.
• Volumetric quantification of antennal lobes and mushroom bodies using reconstructed SLOTy images.
• Neurobiotin labeling to confirm regeneration of afferents.

Main Results:

• Antennal lobes with ablated antennae lost up to 60% of their initial volume within three weeks.
• Antennal lobes with crushed antennal nerves initially shrank but recovered to normal size within three weeks.
• Degeneration of olfactory axons induced trans-synaptic effects, reducing mushroom body calyx size.

Conclusions:

• SLOTy is a suitable method for rapid screening of volumetric plasticity in insect brains.
• The findings highlight differential impacts of nerve injury versus complete ablation on brain structures.
• SLOTy shows potential for application in vertebrate preparations.