And with a bit more research our doctors could use this mapping on us to see where our brain networks are damaged. Then we could figure out what stroke protocols will fix that damage and everybody will live happily ever after. When pigs fly.
In new research published today by Nature Methods, scientists from
the Hebrew University of Jerusalem and Harvard University have announced
a “Neuronal Positioning System” (NPS) that maps the circuitry of the
brain, similar to how a Global Positioning System (GPS) receiver
triangulates one’s location on the planet.
For more than a century, neuroscientists have tried to uncover the
structure of the brain’s neuronal circuits in order to better understand
how the brain works. These brain circuits, which perform functions such
as processing information and triggering reflexes, are comprised of
nervous system cells called neurons that work together to carry out a
specialized function. Neurons send the messages to other neurons, or to
target tissues such as skin and muscle that they innervate, via
specialized wire-like processes called axons.
In the same way that we need to know the exact wiring of an
electrical circuit to understand how it works, it’s necessary to map the
axonal wiring of neuronal circuits to understand how they function.
Therefore a fundamental goal of neuroscience research is to understand
the structural and functional connections of the brain's circuits.
While numerous scientific consortiums have advanced our understanding
of neuronal organization, the available mapping techniques remain
imperfect: for example, serial electron microscope techniques are
limited in the area they can map, and tracer-based techniques are
limited in the detail resolution.
Now, scientists from Dr. Alex Binshtok's laboratory at the Hebrew
University’s Faculty of Medicine and Dr. Jeff Lichtman's laboratory at
Harvard University have described a method to map the location of the
axonal branches (“arbors”) of many individual neurons simultaneously, at
the resolution of individual axons. Thus, by “seeing” many axons in the
same preparation, it becomes possible to understand how specific
neurons in one region are wired to other neuronal types and other
regions.
This new approach makes it possible to learn about organizational
principles of neuronal networks that would otherwise be difficult or
impossible to study.
The research was conducted by Dr. Shlomo Tsuriel, a postdoctoral
fellow from Dr. Alex Binshtok’s lab and the study’s lead author, with
help from student Sagi Gudes, under the guidance of Dr. Binshtok at the
Hebrew University’s Faculty of Medicine (Department of Medical
Neurobiology at the Institute for Medical Research Israel Canada) and at
The Edmond and Lily Safra Center for Brain Sciences. The research was
conducted in collaboration with Dr. Jeff Lichtman from Harvard
University’s Center for Brain Science and Department of Molecular and
Cellular Biology.
Instead of trying to trace entire neurons all the way from the axon
tips to the cell body, Dr. Tsuriel labeled only the cell body, but in a
way that indicates the locations of its axonal branches. To that end, he
used multiple injections in overlapping regions of a target tissue,
with three or more differently colored retrograde tracers.
At each point the tracer was injected in a high concentration and
spread to the area between the injection points, such that each area in
the target tissue had a different color combination depending on its
distance from the injection site. Axons innervating each area took up
the dyes and transported them in small vesicles to the cell body, such
that each vesicle had a color combination reflecting the area it was
taken from. A few hours after the injection, each neuronal cell body was
filled with vesicles in a variety of colors reflecting the colors in
the areas that these neurons innervate. Thus, based on the combinations
and intensities of the colors in the individual vesicles transported to
the cell, the projection sites of the axon can be outlined.
This approach is in some ways analogous to the principle used in a
Global Positioning System (GPS) receiver, which uses distances from
three or more satellites to triangulate its position. For this reason
the new technique was called “Neuronal Positioning System” (NPS).
The description of this new method is presented today in Nature
Methods as “Multispectral labeling technique to map many neighboring
axonal projections in the same tissue” (Advance Online Publication,
doi:10.1038/nmeth.3367).
According to Hebrew University’s Dr. Alex Binshtok: “The new method
that we developed allows us to answer a ‘big question’ in neuroscience
about the organizational principles of neuronal circuits. Using the NPS
technique that maps many axons in same tissue, we now can study what
defines the routes along which the neurons will send their projections,
as well as their targets. We can also learn how the wiring of the
neuronal circuits changes during development and in a variety of
pathological conditions. The answers to these questions will be the
first step to comprehending how the information flows and is processed
in the nervous system, and how changes in the neuronal organization
affect neuronal function. I believe many scientists will find the NPS
approach useful to help them answer the question of how the brain
works.”
Support for the research came from the Humans Frontiers Science
Foundation, European Research Council (ERC) under the European Union’s
Seventh Framework Programme, US National Institute of Mental Health and
US National Institutes of Health.
