(Image caption: This image shows an artificial connection that connects brain to spinal circuits. Credit: © Yukio Nishimura)

Bypass commands from the brain to legs through a computer

Gait disturbance in individuals with spinal cord injury is attributed to the interruption of neural pathways from brain to the spinal locomotor center, whereas neural circuits locate below and above the lesion maintain most of their functions. An artificial connection that bridges the lost pathway and connects brain to spinal circuits has potential to ameliorate the functional loss. A Japanese research group led by Shusaku Sasada, research fellow and Yukio Nishimura, associate professor of the National Institute for Physiological Sciences (NIPS), National Institutes of Natural Sciences (NINS) has successfully made an artificial connection from the brain to the locomotion center in the spinal cord by bypassing with a computer interface. This allowed subjects to stimulate the spinal locomotion center using volitionally-controlled muscle activity and to control walking in legs. This result was published online in The Journal of Neuroscience on August 13, 2014.

Neural networks in the spinal cord, locomotion center are capable of producing rhythmic movements, such as swimming and walking, even when isolated from the brain. The brain controls spinal locomotion center by sending command to the spinal locomotion center to start, stop and change waking speed. In most cases of spinal cord injury, the loss of this link from the brain to the locomotion center causes problems with walking.

The research group came up with bypassing the functioning brain and locomotion center with the computer to compensate lost pathways as a way to enable individuals with spinal cord injury to regain walking ability.

Since the arm movement associate with leg movement when we walk they used muscle activity of arm to sarogate the brain activity. The computer interface allowed subjects to control magnetic stimulator that drive to the spinal locomotion center non-invassively using volitionally-controlled muscle activity and to control walking in legs. As a results of experiments in people who are neurologically intact, the subjects were asked to make own legs relaxed and passively controlled via computer interface that was controlled by arm muscle, walking behavior in legs was induced and subjects could control the step cycle volitionally as well. However without bypassing with the computer interface, the legs did not move even if the arms muscle was volitionally acivated.

"We hope that this technology would compensate for the interrupted pathways’ function by sending an intentionally encoded command to the preserved spinal locomotor center and regain volitionally-controlled walking in indviduals with paraplegia. However, the major challenge that this technology does not help them to dodge obstacles and to maintain posture. We are carefully working toward clinical application in near future", Nishimura said.

Running, Combined with Visual Experience, Restores Brain Function

In a new study by UC San Francisco scientists, running, when accompanied by visual stimuli, restored brain function to normal levels in mice that had been deprived of visual experience in early life.

In addition to suggesting a novel therapeutic strategy for humans with blindness in one eye caused by a congenital cataract, droopy eyelid, or misaligned eye, the new research—the latest in a series of UCSF studies exploring effects of locomotion on brain function—suggests that the adult brain may be far more capable of rewiring and repairing itself than previously thought.

In 2010, Michael P. Stryker, PhD, the W.F. Ganong Professor of Physiology, and postdoctoral fellow Cris Niell, PhD, now at the University of Oregon, made the surprising discovery that neurons in the visual area of the mouse brain fired much more robustly whenever the mice walked or ran.

Earlier this year, postdoctoral fellow Yu Fu, PhD, Stryker and a number of colleagues built on these findings, identifying and describing the neural circuit responsible for this locomotion-induced “high-gain state” in the visual cortex of the mouse brain.

Neither of these studies made clear, however, whether this circuit might have broader functional or clinical significance.

It has been known since the 1960s that visual areas of the brain do not develop normally if deprived of visual input during a “critical period” of brain development early in life. For example, in humans, if amblyopia (“lazy eye”) or other major eye problems are not surgically corrected in infancy, vision will never be normal in the affected eye—if such individuals lose sight in their “good” eye in later life, they are blind.

In the new research, published June 26, 2014 in the online journal eLife, Stryker and UCSF postdoctoral fellow Megumi Kaneko, MD, PhD, closed one eyelid of mouse pups at about 20 days after birth, and that eye was kept closed until the mice reached about five months of age.

As expected, the mice in which one eye had been closed during the critical developmental period showed sharply reduced neural activity in the part of the brain responsible for vision in that eye.

As in the previous UCSF experiments in this area, some mice were allowed to run freely on Styrofoam balls suspended on a cushion of air while recordings were made from their brains.

Little improvement was seen in the mice that had been deprived of visual input either when they were simply allowed to run or when they received visual training with the deprived eye not accompanied by walking or running.

But when the mice were exposed to the visual stimuli while they were running or walking, the results were dramatic: within a week the brain responses to those stimuli from the deprived eye were nearly identical to those from the normal eye, indicating that the circuits in the visual area of the brain representing the deprived eye had undergone a rapid reorganization, known in neuroscience as “plasticity.”

Interestingly, this recovery was stimulus-specific: if the brain activity of the mice was tested using a stimulus other than that they had seen while running, little or no recovery of function was apparent.

“We have no idea yet whether running puts the human cortex into a high-gain state that enhances plasticity, as it does the visual cortex of the mouse,” Stryker said, “but we are designing experiments to find out.”

Your brain on speed: Walking doesn’t impair thinking and multitasking

When we’re strolling down memory lane, our brains recall just as much information while walking as while standing still—findings that contradict the popular science notion that walking hinders one’s ability to think.

University of Michigan researchers at the School of Kinesiology and the College of Engineering examined how well study participants performed a very complex spatial cognitive task while walking versus standing still.

"We’re saying that at least for this task, which is fairly complicated, walking and thinking does not compromise your thinking ability at all," said Julia Kline, a U-M doctoral candidate in biomedical engineering and first author on the study, which appears online in Frontiers in Human Neuroscience.

The finding surprised researchers, who expected to see decreased thinking performance with increased walking speed, Kline said. The 2011 best-selling book “Thinking Fast and Slow” suggests that because walking requires mental effort, walking may hinder our ability to think when compared to standing still.

"Past studies that have compared mental performance at a slow walking speed and standing have not found any differences, but our study is the first to show that the walking speed doesn’t matter," said Daniel Ferris, professor of kinesiology and biomedical engineering and senior author of the paper.

"Given the health benefits of walking, we should not discourage people from walking and thinking when they want."

Ferris offered one caveat: previous research has shown that walking performance can be impaired in the elderly when they dual-task during gait.

Ferris, Kline and Katherine Poggensee of U-M’s Human Neuromechanics Laboratory measured the ability of young, healthy participants to memorize numbers and their placement on a grid, and then enter those numbers correctly with a keypad while walking different speeds and standing still.

"Think of filling numbers one through nine on a tic-tac-toe grid and then remembering where they all are," Ferris said. "At every walking speed and standing still, participants entered about half the numbers correctly."

While speed didn’t change task performance, people took wider steps when performing the task than when they were only walking, which may be to compensate and stay balanced while concentrating, Kline said.

All participants showed increased activity in areas of the brain associated with spatial relationships and short-term memory during the cognitive task. In keeping with the U-M findings, a recent Stanford study suggested that walking fueled creativity.

In addition to good news for treadmill-desk users or people who like to think on the move, the study provides a useful scientific tool by demonstrating that it’s possible to collect accurate EEG data on moving subjects, Kline said.

This is important to researchers who study the brain and are concerned about getting accurate results when the subjects aren’t perfectly still. U-M researchers achieved their EEG results by applying different signal-processing techniques to eliminate the movement “noise” from the EEG signal.

Findings Could Help Explain Origins of Human Limb Control

We might have more in common with a lamprey than we think, according to a new Northwestern University study on locomotion. At its core, the study of transparent zebrafish addresses a fundamental evolution issue: How did we get here?

Neuroscientists Martha W. Bagnall and David L. McLean have found that the spinal cord circuits that produce body bending in swimming fish are more complicated than previously thought.

Vertebrate locomotion has evolved from the simple left-right bending of the body exemplified by lampreys to the appearance of fins in bony fish to the movement of humans, with the complex nerve and muscle coordination necessary to move four limbs.

Bagnall and McLean report that differential control of an animal’s musculature — the basic template for controlling more complex limbs — is already in place in the spinal networks of simple fish. Neural circuits in zebrafish are completely segregated: individual neurons map to specific muscles.

Specifically, the neural circuits that drive muscle movement on the dorsal (or back) side are separate from the neural circuits activating muscles on the ventral (or front) side. This is in addition to the fish being able to separately control the left and right sides of its body [Video]

Ultimately, understanding more about how fish swim will allow scientists to figure out how humans walk.

“Evolution builds on pre-existing patterns, and this is a critical piece of the puzzle,” McLean said. “Our data help clarify how the transition from water to land could have been accomplished by simple changes in the connections of spinal networks.”

The findings will be published Jan. 10 in the journal Science. McLean, an assistant professor of neurobiology in the Weinberg College of Arts and Sciences, and Bagnall, a postdoctoral fellow in his research group who made the discovery, are authors of the paper.

“This knowledge will put us in a better position to devise more effective therapies for when things go wrong with neural circuits in humans, such as spinal cord damage,” McLean said. “If you want to fix something, you have to know how it works in the first place. Given that the fish spinal cord works in a similar fashion to our own, this makes it a fantastic model system for research.”

McLean and Bagnall studied the motor neurons of baby zebrafish because the fish develop quickly and are see-through. They used state-of-art imaging techniques to monitor and manipulate neuronal activity in the fish.

“You can stare right into the nervous system,” McLean said. “It’s quite remarkable.”

The separate circuits for moving the left and right and top and bottom of the fish allow the animal to twist its body upright when it senses that it has rolled too far to one side or the other.

“This arrangement is perfectly suited to provide rapid postural control during swimming,” Bagnall said. “Importantly, this ancestral pattern of spinal cord organization may also represent an early functional template for the origins of limb control.”

Separate control of dorsal and ventral muscles in the fish body is a possible predecessor to separate control of extensors and flexors in human limbs. By tweaking the connections between these circuits as they elaborated during evolution, it is easier to explain how more complicated patterns of motor coordination in the limbs and trunk could have arisen during dramatic evolutionary changes in the vertebrate body plan, the researchers said.

“We are teasing apart basic components of locomotor circuits,” McLean said. “The molecular mechanisms responsible for building spinal circuits are conserved in all animals, so this study provides a nice hypothesis that scientists can test.”

Why humans are musical

Why don’t apes have musical talent, while humans, parrots, small birds, elephants, whales, and bats do? Matz Larsson, senior physician at the Lung Clinic at Örebro University Hospital, attempts to answer this question in the scientific publication Animal Cognition.

In his article, he asserts that the ability to mimic and imitate things like music and speech is the result of the fact that synchronised group movement quite simply makes it possible to perceive sounds from the surroundings better.

The hypothesis is that the evolution of vocal learning, that is musical traits, is influenced by the need of a species to deal with the disturbing sounds that are created in connection with locomotion. These sounds can affect our hearing only when we move.

“When several people with legs of roughly the same length move together, we tend to unconsciously move in rhythm. When our footsteps occur simultaneously, a brief interval of silence occurs. In the middle of each stride we can hear our surroundings better. It becomes easier to hear a pursuer, and perhaps easier to conduct a conversation as well,” explains Larsson.

A behaviour that has survival value tends to produce dopamine, the “reward molecule”. In dangerous terrain, this could result in the stimulation of rhythmic movements and enhanced listening to surrounding sounds in nature. If that kind of synchronized behaviour was rewarding in dangerous environments it may as well have been rewarding for the brain in relative safety, resulting in activities such as hand- clapping, foot-stamping and yelping around the campfire. From there it is just a short step to dance and rhythm. The hormone dopamine flows when we listen to music.