Cross-species lesion mapping links a midbrain circuit to vergence dysfunction

Area of Science:

• Neuroscience
• Ophthalmology
• Neurology

Background:

• Vergence eye movements enable focus in three-dimensional space.
• Dysfunction in vergence is observed in up to 40% of patients with neurodegenerative disorders.
• The precise neural mechanisms underlying vergence deficits in humans remain unclear.

Purpose of the Study:

• To elucidate the neural basis of vergence dysfunction in humans.
• To bridge the translational gap between animal models and human clinical observations of vergence control.

Main Methods:

• Voxel-wise lesion mapping was conducted in 66 humans and 19 monkeys with midbrain lesions.
• Cross-species connectivity analyses were performed to map brain circuits involved in vergence.

Main Results:

• Vergence dysfunction was causally linked to a midbrain region rostral to the superior colliculus, centered on the nucleus of the posterior commissure (NPC).
• A conserved brain circuit connecting the NPC to visual pretectum and premotor hubs was identified across species.

Conclusions:

• The nucleus of the posterior commissure (NPC) plays a critical role in human vergence control.
• This research provides a neuroanatomical foundation for understanding vergence dysfunction in neurodegenerative diseases.
• Lesion mapping effectively connects animal model findings with human clinical data.