Removing a single neuron in a vertebrate brain forever abolishes an essential behavior

Area of Science:

• Neuroscience
• Behavioral Biology
• Vertebrate Zoology

Background:

• The giant Mauthner (M) cell is the largest neuron in vertebrates, implicated in rapid escape responses.
• Its precise function and survival value have remained unclear, with experimental evidence lacking and escape behaviors persisting after M-cell ablation.

Purpose of the Study:

• To investigate the Mauthner cell's role in escape behavior and survival.
• To determine if the Mauthner cell axon alone can drive escape responses after soma removal.
• To experimentally test the survival value of Mauthner cell-mediated escapes.

Main Methods:

• Simultaneous measurement of escape performance and Mauthner axon state after soma ablation.
• Unilateral removal of one Mauthner axon to compare escape capabilities with and without M-axon recruitment.
• Experimental encounters with a natural predator to assess survival rates.

Main Results:

• The Mauthner cell axon survives soma ablation for extended periods and remains functional for rapid escape behavior.
• Unilateral M-axon removal permanently abolished rapid escapes in affected individuals.
• Absence of the giant Mauthner axon significantly reduced survival rates during predator encounters.

Conclusions:

• The giant Mauthner axon is essential for rapid escape behavior and confers a significant survival advantage.
• Complex brains can rely on individual neurons for critical functions, necessitating mechanisms for axon survival.
• This study resolves a long-standing neuroscience puzzle regarding the Mauthner cell's function.