Ipsilaterally projecting rubrospinal neurons in adult and developing opossums

Area of Science:

• Neuroscience
• Developmental Neuroscience
• Comparative Neurology

Background:

• The rubrospinal tract is a major descending motor pathway.
• Its role in locomotion and motor control is well-established.
• The existence and extent of an ipsilateral rubrospinal projection remain incompletely understood.

Purpose of the Study:

• To determine if an ipsilateral rubrospinal projection exists in adult and developing opossums.
• To characterize the rubral neurons that give rise to this projection.

Main Methods:

• Injections of Fast Blue tracer into the spinal cord.
• Lesions of the rubrospinal tract rostral and contralateral to the injections.
• Quantitative and image analysis of retrogradely labeled rubral neurons.

Main Results:

• A small but significant ipsilateral rubrospinal projection was identified.
• Approximately 0.6% of rubrospinal neurons project ipsilaterally in adult opossums.
• Ipsilateral and contralateral projecting rubral neurons are comparable in location and size.
• Similar findings were observed in developing opossums.

Conclusions:

• The rubrospinal tract in opossums exhibits a predominantly contralateral projection with a minor ipsilateral component.
• These findings contribute to understanding rubrospinal tract development and plasticity.