Virginia Tech scientists have improved their method of mapping the zebrafish brain, a breakthrough that could improve understanding of how the human brain works.
“A brain wiring diagram would be a powerful tool in understanding connectivity diseases,” said Yuchin Albert Pan, a prominent Commonwealth Research Commercialization Fund researcher in developmental neuroscience at the Fralin Biomedical Research Institute at VTC. “Autism spectrum disorders, for example, are characterized by a loss of long distance connections and an increase in local connections. Most neuropsychiatric disorders have aspects of connectivity. “
Although human brains are more complex, zebrafish brains share a common architecture like all vertebrates. Determining the structure and function of cells called neurons and how they connect in the brain and between the brain and other structures such as the eye could provide clues to more specifically treat neurological diseases and eye damage.
In a study published today Frontiers in neuroanatomy, scientists reported an improved viral technique for tracing brain connections between zebrafish neurons using vesicular stomatitis virus (VSV), which tags cells as it spreads through synaptic connections between neurons that are functionally “wired” together.
Until now, the use of viral vectors in zebrafish has been limited because viruses, such as rabies or adeno-associated viruses, often used by scientists to transfer molecules to mammalian cells, are not effective in mammalian cells. the fish.
To overcome this limitation, scientists at Virginia Tech have tried and validated the use of VSV to trace connection patterns in zebrafish neurons. The virus was designed to tag excitatory and inhibitory neurons that are connected via a nanoscopic structure called a synapse.
Prior to this study, researchers had been successful with the approach, but the improved second-generation version of the technique used a mutant version of VSV that was less toxic and lasted longer in cells, making it possible to visualize connected neurons. and the analysis of this possible connectivity up to five days after infection.
“It’s really exciting because now we can not only record the activity, but we also know something about the cell types involved and how they connect,” said co-lead author Manxiu “Michelle” Ma, neurophysiologist and former postdoctoral researcher. partner in the Pan laboratory. “The unique viral tracer benefits from reduced cytotoxicity, which allows neurons infected with the virus to maintain cell integrity and express a fluorescent indicator to reveal neuronal activity upon visual stimulation. In addition, this technique can also define the type of neuron, for example, whether the neuron during a visual stimulus is an excitatory neuron or an inhibitory neuron.
Stanislav Kler, virologist and lead co-author of the study who was also a postdoctoral research associate in the lab, said: “The patterns of connectivity between most types of neurons are mostly unknown. This knowledge gap underscores the critical need for effective neural circuit mapping tools. This will allow us to better understand how the brain stores and processes information and how we can manipulate these circuits for better health. ”
Research is particularly important for vision research.
“To restore vision after diseases or injuries that affect the eye itself, including cells in the eye that project into deep structures in the brain for further processing of the visual world, the eye must connect to the right places in the brain, ”said Pan, who is a member of the Neurobiology Research Center at the Fralin Biomedical Research Institute. “The small size and translucency of zebrafish larvae is a unique experimental system for studying the neural circuits of the entire brain. Scientists working on vision regeneration can now verify if there is functional connectivity.
The study was supported by the National Eye Institute of the National Institutes of Health, the Commonwealth Research Commercialization Fund and Virginia Tech.
Frontiers in neuroanatomy
The title of the article
Cre-dependent anterograde transsynaptic labeling and functional imaging in zebrafish using reduced cytotoxicity VSV
Publication date of the article
The authors state that the research was conducted in the absence of any business or financial relationship that could be interpreted as a potential conflict of interest.
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