Manipulation of a specific neural circuit buried in complicated brain networks in primates

June 17, 2012

A collaborative research team led by Professor Tadashi ISA from The National Institute for Physiological Sciences, The National Institutes of Natural Sciences and Fukushima Medical University and Kyoto University, developed a "double viral vector transfection technique" which can deliver genes to a specific neural circuit by combining two new kinds of gene transfer vectors. With this method, they found that "indirect pathways", which were suspected to have been left behind when the direct connection from the brain to motor neurons (which control muscles) was established in the course of evolution, actually plays an important role in the highly developed dexterous hand movements. This study was supported by the Strategic Research Program for Brain Sciences by the MEXT of Japan. This research result will be published in Nature (June 17th, advance online publication).

It is said that the higher primates including human beings accomplished explosive evolution by having acquired the ability to move hands skillfully. It has been thought that this ability to move individual fingers is a result of the evolution of the direct connection from the cerebrocortical motor area to of the spinal cord which control the muscles. On the other hand, in lower animals with clumsy hands, such as cats or rats, the cortical motor area is connected to the motor neurons, only through of the spinal cord. Such "indirect pathway"remains in us, primates, without us fully understanding its functions. Is this "phylogenetically old circuit" still in operation? Or maybe suppressed since it is obstructive? The conclusion was not attached to this argument.

The collaborative research team led by Professor Tadashi ISA, Project Assistant Professor Masaharu KINOSHITA from The National Institute for Physiological Sciences, The National Institutes of Natural Sciences and Fukushima Medical University and Kyoto University developed "the double transfection technique"which can deliver genes to a specific by combining two new kinds of vectors.

With this method, they succeeded in the selective and reversible suppression of the propriospinal neurons (spinal interneurons mediating the indirect connection from cortical motor area to spinal motor neurons)

The results revealed that "indirect pathways" play an important role in dexterous hand movements and finally a longtime debate has come to a close.

The key component of this discovery was"the double viral vector transfection technique"in which one vector is retrogradely transported from the terminal zone back to the neuronal cell bodies and the other is transfected at the location of their cell bodies. The expression of the target gene is regulated only in the cells with double transfection by the two vectors. Using this technique, they succeeded in the suppression of the propriospinal neuron selectively and reversibly.

Such an operation was possible in mice in which the inheritable genetic manipulation of germline cells were possible, but impossible in primates until now.

Using this method, further development of gene therapy targeted to a specific neural circuit can be expected.

Professor Tadashi ISA says "this newly developed double viral vector transfection technique can be applied to the gene therapy of the human central nervous system, as we are the same higher primates.

And this is the discovery which reverses the general idea that the spinal cord is only a reflex pathway, but also plays a pivotal role in integrating the complex neural signals which enable dexterous movements."

Explore further: Anatomical blueprint for motor antagonism identified

Related Stories

Anatomical blueprint for motor antagonism identified

October 20, 2011
(Medical Xpress) -- Walking or movement in general, comes so naturally to us, yet it results from a sophisticated interplay between the nervous system and muscles. Little is known about the neuronal blueprint that ensures ...

Recommended for you

Researchers make surprising discovery about how neurons talk to each other

August 17, 2017
Researchers at the University of Pittsburgh have uncovered the mechanism by which neurons keep up with the demands of repeatedly sending signals to other neurons. The new findings, made in fruit flies and mice, challenge ...

How we recall the past: Neuroscientists discover a brain circuit dedicated to retrieving memories

August 17, 2017
When we have a new experience, the memory of that event is stored in a neural circuit that connects several parts of the hippocampus and other brain structures. Each cluster of neurons may store different aspects of the memory, ...

Researchers show how particular fear memories can be erased

August 17, 2017
Researchers at the University of California, Riverside have devised a method to selectively erase particular fear memories by weakening the connections between the nerve cells (neurons) involved in forming these memories.

Neurons involved in learning, memory preservation less stable, more flexible than once thought

August 17, 2017
The human brain has a region of cells responsible for linking sensory cues to actions and behaviors and cataloging the link as a memory. Cells that form these links have been deemed highly stable and fixed.

Study uncovers specialized mouse neurons that play a unique role in pain

August 17, 2017
Researchers from the National Institutes of Health have identified a class of sensory neurons (nerve cells that electrically send and receive messages between the body and brain) that can be activated by stimuli as precise ...

Scientists identify central neural circuit for itch sensation

August 17, 2017
Itching is an unpleasant sensation associated with the desire to scratch, and the itch sensation is an important protective mechanism for animals. However, chronic itch, often seen in patients with skin and liver diseases, ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.