Newborn babies walk the walk

Before you can run, you have to walk, and before you can walk well, you have to walk like a brand-new baby. A new study uncovers the logistics of newborns’ herky-jerky, Frankensteinian stepping action and how this early reflex morphs into refined adult locomotion.

In the study, electrodes on infants’ chubby legs picked up signals from neurons that tell muscles to fire, revealing that three-day old babies tense up many of their leg muscles all at once. Toddlers, preschoolers and adults, by contrast, showed a progressively more sophisticated, selective pattern of neuron activity.

From birth to adulthood, motor neurons in the spine get an overhaul as neurons in different  locations along the spine become specialized for various aspects of walking, such as foot position, balance and direction, Yuri Ivanenko of the Santa Lucia Foundation in Rome and colleagues conclude in the Feb. 13 Journal of Neuroscience.

Research Institute Study Shows How Brain Cells Shape Temperature Preferences

While the wooly musk ox may like it cold, fruit flies definitely do not. They like it hot, or at least warm. In fact, their preferred optimum temperature is very similar to that of humans—76 degrees F.

Scientists have known that a type of brain cell circuit helps regulate a variety of innate and learned behavior in animals, including their temperature preferences. What has been a mystery is whether or not this behavior stems from a specific set of neurons (brain cells) or overlapping sets.

Now, a new study from The Scripps Research Institute (TSRI) shows that a complex set of overlapping neuronal circuits work in concert to drive temperature preferences in the fruit fly Drosophila by affecting a single target, a heavy bundle of neurons within the fly brain known as the mushroom body. These nerve bundles, which get their name from their bulbous shape, play critical roles in learning and memory.

The study, published in the January 30, 2013 edition of the Journal of Neuroscience, shows that dopaminergic circuits—brain cells that synthesize dopamine, a common neurotransmitter—within the mushroom body do not encode a single signal, but rather perform a more complex computation of environmental conditions.

“We found that dopamine neurons process multiple inputs to generate multiple outputs—the same set of nerves process sensory information and reward-avoidance learning,” said TSRI Assistant Professor Seth Tomchik. “This discovery helps lay the groundwork to better understand how information is processed in the brain. A similar set of neurons is involved in behavior preferences in humans—from basic rewards to more complex learning and memory.”

Using imaging techniques that allow scientists to visualize neuron activity in real time, the study illuminated the response of dopaminergic neurons to changes in temperature. The behavioral roles were then examined by silencing various subsets of these neurons. Flies were tested using a temperature gradient plate; the flies moved from one place to another to express their temperature preferences.

As it turns out, genetic silencing of dopaminergic neurons innervating the mushroom body substantially reduces cold avoidance behavior. “If you give the fly a choice, it will pick San Diego weather every time,” Tomchik said, “but if you shut down those nerves, they suddenly don’t mind being in Minnesota.”

The study also showed dopaminergic neurons respond to cooling with sudden a burst of activity at the onset of a drop in temperature, before settling down to a lower steady-state level. This initial burst of dopamine could function to increase neuronal plasticity—the ability to adapt—during periods of environmental change when the organism needs to acquire new associative memories or update previous associations with temperature changes.

(Image: ALAMY)

Dragonflies have human-like ‘selective attention’

In a discovery that may prove important for cognitive science, our understanding of nature and applications for robot vision, researchers at the University of Adelaide have found evidence that the dragonfly is capable of higher-level thought processes when hunting its prey.

The discovery, published online in the journal Current Biology, is the first evidence that an invertebrate animal has brain cells for selective attention, which has so far only been demonstrated in primates.

Dr Steven Wiederman and Associate Professor David O’Carroll from the University of Adelaide’s Centre for Neuroscience Research have been studying insect vision for many years.

Using a tiny glass probe with a tip that is only 60 nanometres wide - 1500 times smaller than the width of a human hair - the researchers have discovered neuron activity in the dragonfly’s brain that enables this selective attention.

They found that when presented with more than one visual target, the dragonfly brain cell ‘locks on’ to one target and behaves as if the other targets don’t exist.

"Selective attention is fundamental to humans’ ability to select and respond to one sensory stimulus in the presence of distractions," Dr Wiederman says.

Associate Professor O’Carroll says this brain activity makes the dragonfly a more efficient and effective predator.

"Recent studies reveal similar mechanisms at work in the primate brain, but you might expect it there. We weren’t expecting to find something so sophisticated in lowly insects from a group that’s been around for 325 million years, Associate Professor O’Carroll says.

"We believe our work will appeal to neuroscientists and engineers alike. For example, it could be used as a model system for robotic vision. Because the insect brain is simple and accessible, future work may allow us to fully understand the underlying network of neurons and copy it into intelligent robots," he says.