Science & Tech News

Growing Nerves

Our nervous system is made up of the brain, spinal cord and neurons [nerves] – an intricate network that allows our brain to communicate with the rest of our body. Development of the human nervous system begins when an embryo is in its 5th week. Neurons extend a projection from their cell body called the axon (pictured in green, pink and blue in a developing mouse spinal cord) along a specific path in response to a variety of molecular cues, systematically guiding its journey to the spinal cord (left) and eventually the wider body, establishing the nervous system. One particular molecular cue called netrin1 organises axon growth, but researchers have been trying to understand how. By halting the activity of netrin1, axon growth was disrupted and highly disorganised (right), highlighting how netrin1 influences axon growth and providing insight into how researchers could regenerate axons in people with nerve damage.

Written by Katie Pantell

Image from work by Supraja G. Varadarajan and colleagues, Broad Center, UCLA

Department of Neurobiology, University of California, Los Angeles, CA, USA

Image copyright held by original authors

Research published in Neuron, May 2017

Nerve cells in our brains work together in harmony to store and retrieve short-term memory, and are not solo artists as was previously thought, Western-led brain research has determined.

The research turns on its head decades of studies assuming that single neurons independently encode information in our working memories.

“These findings suggest that even neurons we previously thought were ‘useless’ because they didn’t individually encode information have a purpose when working in concert with other neurons,” said researcher Julio Martinez-Trujillo, based at the Robarts Research Institute and the Brain and Mind Institute at Western University.

“Knowing they work together helps us better understand the circuits in the brain that can either improve or hamper executive function. And that in turn may have implications for how we work though brain-health issues where short-term memory is a problem, including Alzheimer disease, schizophrenia, autism, depression and attention deficit disorder.”

Working memory is the ability to learn, retain and retrieve bits of information we all need in the short term: items on a grocery list or driving directions, for example. Working memory deteriorates faster in people with dementia or other disorders of the brain and mind.

In the past, researchers have believed this executive function was the job of single neurons acting independently from one another – the brain’s version of a crowd of people in a large room all singing different songs in different rhythms and different keys. An outsider trying to decipher any tune in all that white noise would have an extraordinarily difficult task.

This research, however, suggests many in the neuron throng are singing from the same songbook, in essence creating chords to strengthen the collective voice of memory. With neural prosthetic technology – microchips that can “listen” to many neurons at the same time – researchers are able to find correlations between the activity of many nerve cells. “Using that same choir analogy, you can start perceiving some sounds that have a rhythm, a tune and chords that are related to each other: in sum, short-term memories,” said Martinez-Trujillo, who is also an associate professor at Western’s Schulich School of Medicine & Dentistry.

And while the ramifications of this discovery are still being explored, “this gives us good material to work with as we move forward in brain research. It provides us with the necessary knowledge to find ways to manipulate brain circuits and improve short term memory in affected individuals,” Martinez-Trujillo said.

After 40 years, scientists may have solved the mystery of the “Wow!” space signal

In August of 1977, a group of astronomers examining radio transmissions in Ohio received a mysterious signal from an unknown source.

Shocked by its incredible length — 72 seconds — one scientist scribbled “Wow!” next to the recording, inadvertently giving the unusual communication a nickname that would last decades.

Now, after 40 years of grappling with possible explanations for the Wow! signal — which even include the possibility of aliens — scientists at the Center for Planetary Science have finally solved the puzzle.

A comet unknown to researchers in the 1970s likely caused the signal, and researchers were able to test that theory in a recent fly-by. Read more (6/8/17)

Not everyone is on board with the recent “Wow!” signal discovery.

Alan Fitzsimmons, a scientist at the United Kingdom’s Queens University Belfast, told Astronomy Now that it’s actually “rubbish.”

He claims that a 1420-MHZ signal from a comet has never been detected before, and that the 266/P Christensen would be too quiet, even at perihelion — the point that a comet is closest to the sun.

Our nervous systems have left-right differences that are important for correct functioning. Handedness is probably the best-known asymmetry arising from the development of the nervous system. This is observed very early on: embryos of eight weeks already tend to move their right arms more often than their left arms. At this ‘age’ signals are not sent from the brain to the arms yet, but only from the spinal cord. A few weeks later, left-right differences also become visible in the shape and size of the premature brain.

A team of scientists from the Netherlands, the UK and China searched for genes that contribute to left-right differences in the nervous system, in the period between four and eight weeks after fertilisation. The genetic analysis showed that the left and right sides of the spinal cord develop at different paces.

The left side of the spinal cord matures slightly faster than the right side. Sets of key genes that control growth and maturity were found to reach a more advanced profile of activity on the left side than the right. In the hindbrain, an area which is the predecessor for some adult parts of the brain, this was the other way around.

“This seems logical, since many nerve fibers cross over from one side to the other at the boundary between the hindbrain and spinal cord,” says Carolien de Kovel, lead author of the study and researcher at the Max Plank Institute for Psycholinguistics (MPI). “How exactly this left-right genetic difference in the spinal cord leads to right-handedness is, however, not yet clear.”

Clyde Francks, head of the MPI research group ‘Brain and behavioral asymmetries’ and Research Fellow at the Donders Institute at the Radboud University, explains, “We think that these very early left-right differences in the spinal cord may act to trigger some of the later asymmetries of the brain, such as the eventual dominance of the left hemisphere for language functions in most adults’.

Asymmetry and schizophrenia "Around 85% of humans are right-handed; it seems the standard in human development,” De Kovel adds, “but genetic and environmental factors may provide alternative paths of development, such as left-handedness or two-handedness. Interestingly, disturbances in such asymmetries seem to be more common in people with psychiatric conditions such as schizophrenia.”