'Mini-brain' in spinal cord helps body balance

A cluster of neurons in our spinal cord function as a "mini-brain" to help keep our bodies in balance, scientists say.
A new discovery suggests that much of the balancing act that our bodies perform when faced with certain tasks happens unconsciously, thanks to the cluster of neurons in our spinal cord to integrate sensory information and make the necessary adjustments to our muscles so that we don't slip and fall.
The study, conducted in mice, provides the first detailed blueprint for a spinal circuit that serves as control centre for integrating motor commands from the brain with sensory information from the limbs.

A better understanding of these circuits should eventually aid in developing therapies for spinal cord injury and diseases that affect motor skills and balance, as well as the means to prevent falls for the elderly, researchers said.
"When we stand and walk, touch sensors on the soles of our feet detect subtle changes in pressure and movement. These sensors send signals to our spinal cord and then to the brain," said Martyn Goulding, a Salk Institute for Biological Studies professor and senior author on the paper.
"Our study opens what was essentially a black box, as up until now we didn't know how these signals are encoded or processed in the spinal cord. Moreover, it was unclear how this touch information was merged with other sensory information to control movement and posture," said Goulding.

While the brain's role in cerebral achievements such as philosophy, mathematics and art often take centre stage, much of what the nervous system does is to use information gathered from our environment to guide our movements.

Walking across that icy parking lot, for instance, engages a number of our senses to prevent us from falling. Our eyes tell us whether we're on shiny black ice or damp asphalt.
Balance sensors in our ear canals keep our heads level with the ground. And sensors in our muscles and joints track the changing positions of our arms and legs.
Every millisecond, multiple streams of information, including signals from the light touch transmission pathway that Goulding's team has identified, flow into the brain.

One way the brain handles this data is by preprocessing it in sensory way stations such as the eye or spinal cord.
The eye, for instance, has a layer of neurons and light sensors at its back that performs visual calculations - a process known as "encoding" - before the information goes on to the visual centres in the brain.
In the case of touch, scientists have long thought that the neurological choreography of movement relies on data-crunching circuits in the spinal cord.
But until now, it has been exceedingly difficult to precisely identify the types of neurons involved and chart how they are wired together.

The research was published in the journal Cell.