Recent find­ings from the Lab­o­ra­tory of Neu­ro­bi­ology at North­eastern, led by biology pro­fessor and chair Gün­ther Zupanc, and pub­lished online in the sci­en­tific journal Neu­ro­science, demon­strate the mech­a­nism by which new neu­rons find their ulti­mate home — research that Zupanc hopes will offer insight into the regen­er­a­tive poten­tial of the human brain.

In 1989, sci­en­tists dis­cov­ered that two areas of the human brain — the hip­pocampus and the olfac­tory bulb — are capable of gen­er­ating neu­rons during adult­hood. In the last decade, adult stem-​​cell research has shown that latent stem cells also exist in other regions. In prin­ciple, this infor­ma­tion could be used to help the brain cure itself by replacing neu­rons lost to injury with new, adult-​​born neu­rons. How­ever, despite the work of thou­sands of research pro­grams, such attempts have failed thus far.“Key to the devel­op­ment of such replace­ment ther­a­pies is to better under­stand what limits the regen­er­a­tive poten­tial of the human brain,” said Zupanc.

His team, which includes North­eastern research asso­ciates Ruxandra Sîr­bulescu and Iulian Ilies, believes that exploring the regen­er­a­tive capac­i­ties of other species can lend insight into the neu­ro­log­ical system of mam­mals. “If there are cer­tain mol­e­cules that are missing in the system, then you can search as much as you want, you will never find them,” said Zupanc.

Bony fish have the ability to grow new brain tissue or part of the spinal cord after a preda­tory attack. This evo­lu­tionary strategy makes them prime can­di­dates for studying neu­ronal regen­er­a­tion, he said.

If sci­en­tists could induce the mam­malian system to mimic the cel­lular behavior of the fish system, it could allow people to heal from trau­matic brain and spinal-​​cord injuries in a matter of weeks, Zupanc said. But neu­ronal regen­er­a­tion, which has been demon­strated in stroke patients, does not itself lead to recovery.

New neu­rons must migrate to a dif­ferent area of the brain to become func­tional, Zupanc explained. His recent inves­ti­ga­tions with teleost fish explore the process of neu­ronal migra­tion, which only occurs with proper guid­ance, he said. Until now, researchers have not known how new neu­rons in the adult fish brain find their way to their target areas, where they inte­grate into the net­work of existing neu­rons and become functional.

The team found that a dif­ferent cell type — the radial glia — guides new neu­rons along a scaf­fold from their birth­place to their ulti­mate home. The same phe­nom­enon has been observed in human embry­onic devel­op­ment. But while teleost fish retain this ability into adult­hood, humans do not.

Without a full under­standing of how neu­rons develop func­tion­ality, these find­ings will remain in the lab as inter­esting research results. Zupanc hopes his inves­ti­ga­tions with fish will add impor­tant insights required to help human patients with neu­ro­log­ical injuries and diseases.