Brain segmentation and trigeminal projections in the lamprey; with reference to vertebrate brain evolution

Area of Science:

• Neuroscience
• Evolutionary Biology
• Developmental Biology

Background:

• Vertebrate brains display significant diversity, stemming from evolutionary alterations in the molecular-level developmental programs of the nervous system.
• Understanding the evolutionary history of this diversity requires examining the developmental morphological plan of the brain.

Purpose of the Study:

• To investigate the evolutionary scenario behind vertebrate brain diversity by analyzing developmental morphology.
• To explore the relationship between brain segmentation and somatotopy in neuronal projections.

Main Methods:

• Comparative analysis of brain organization across non-vertebrate chordates, cyclostomes, and gnathostomes.
• Labeling of the lamprey oral region to visualize trigeminal nerve projections.
• Integration of data on rhombomere segments and neuronal projections.

Main Results:

• A step-wise modification of brain patterning programs is evident through comparative analysis.
• Trigeminal nerve somatotopic projections into the hindbrain become visible upon labeling the lamprey oral region.

Conclusions:

• The study highlights a stepwise evolutionary modification of brain patterning programs.
• It discusses the evolutionary relationship between somatotopy and brain segmentation based on neuronal projections and rhombomere data.