One only needs to imagine an icy sidewalk or slippery pool deck to be reminded of the importance of balance. Walking on ice and other slippery surfaces relies on the brain to constantly make decisions and adjustments. While many studies in neuroscience have been dedicated to examining the brain’s role in tasks like balance, not as many have explored the impact of the spinal cord.
The group of Salk Institute researchers who has discovered a circuit of spinal cord neurons that helps maintain balance.
Source: Salk Institute
A group of researchers at Salk Institute have attempted to change that. Their paper, titled “Identification of a Spinal Circuit for Light Touch and Fine Motor Control”, was published in the journal Cell on January 29. The subject of the paper was a specific collection of neurons located in the spinal cord found to take in and send out information necessary for the feet to maintain balance.
Part of this information comes from touch sensors found on the soles of feet. According to Martyn Goulding – the senior author of the paper – these sensors “detect subtle changes in pressure and movement” (1). Using this information, the brain then creates necessary motor movements to accommodate for these factors. These movements, then, are what the body uses to remain stable on slippery surfaces.
The scientists reached their conclusion by determining that these spinal cord neurons are connected both to the sensory neurons that carry information from the feet and to the motor neurons that command them. Thus, these spinal cord cells – deemed RORα neurons – have been determined to be an integral link in a reflex arc that goes from the feet, to the brain, and to the feet again.
The scientists worked with genetically modified mice to confirm this theory. They disabled the RORα neurons in these mice and then had them perform a series of tasks. They found that the mice could still walk on a standard flat surface, but had trouble walking across a raised beam. The researchers hypothesized that this was because the mice were unable to consistently recognize when their feet were slipping off the edge of the beam and conduct the proper adjustments that would allow them to remain upright (1).
While this knowledge applies to everyone who walks on slippery surfaces, it has particularly important implications for the elderly and those who suffer from spinal cord disease and injuries. Since not much is known in this field, this study represents a critical advance. Goulding, aware that the study represents a critical advance in the little-known field of spinal cord injury, says that “our study opens what was essentially a black box” and that “we’re at the beginning of a real sea change in the field, which is tremendously exciting” (1). In the midst of a potentially icy winter, the excitement is bound to spread.
Sources:
1. Salk Institute for Biological Studies (29 Jan 2015). Walking on ice takes more than brains: ‘Mini-brain’ in spinal cord aids in balance. ScienceDaily. Retrieved February 1, 2015 from www.sciencedaily.com/releases/2015/01/150129132811.htm