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As icy conditions engulf the East Coast, staying upright becomes a key issue for commuters.

Scientists say they have discovered the secret of how we stay upright. 

The claims a 'second brain' in the spinal cord is key -  and can automatically make the necessary adjustments to our muscles so that we don't slip and fall.

Scientists say a 'second brain' in the spinal cord is key to staying upright - and can automatically make the necessary adjustments to our muscles so that we don't slip and fall.

'When we stand and walk, touch sensors on the soles of our feet detect subtle changes in pressure and movement,' said Martyn Goulding, a Salk professor and senior author on the paper.

'These sensors send signals to our spinal cord and then to the brain.

'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.'

The team found a cluster of neurons in our spinal cord that function as a 'mini-brain'. 

In a paper published January 29, 2015 in the journal Cell, Salk Institute scientists map the neural circuitry of the spinal cord that processes the sense of light touch. 

This circuit allows the body to reflexively make small adjustments to foot position and balance using light touch sensors in the feet. 

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.

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 centers in the brain. 

The study, conducted in mice, provides the first detailed blueprint for a spinal circuit that serves as control center for integrating motor commands from the brain with sensory information from the limbs.

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.

In their study, the Salk scientists demystified this fine-tuned, sensory-motor control system. 

Using cutting-edge imaging techniques that rely on a reengineered rabies virus, they traced nerve fibers that carry signals from the touch sensors in the feet to their connections in the spinal cord.

They found that these sensory fibers connect in the spinal cord with a group of neurons known as RORα neurons, named for a specific type of molecular receptor found in the nucleus of these cells.

The RORα neurons in turn are connected by neurons in the motor region of brain, suggesting they might serve as a critical link between the brain and the feet.

'We think these neurons are responsible for combining all of this information to tell the feet how to move,' says Steeve Bourane, a postdoctoral researcher in Goulding's lab and first author on the new paper. 

'If you stand on a slippery surface for a long time, you'll notice your calf muscles get stiff, but you may not have noticed you were using them. 

'Your body is on autopilot, constantly making subtle corrections while freeing you to attend to other higher-level tasks.'