The Experiment

'Haven't my neurons seen this before?'

The world grows increasingly more chaotic year after year, and our brains are constantly bombarded with images. A new study from Center for the Neural Basis of Cognition (CNBC), a joint project between Carnegie Mellon University and the University of Pittsburgh, reveals how neurons in the part of the brain responsible for recognizing objects respond to being shown a barrage of images. The study is published online by Nature Neuroscience.

The CNBC researchers showed animal subjects a rapid succession of images, some that were new, and some that the subjects had seen more than 100 times. The researchers measured the electrical response of individual neurons in the inferotemporal cortex, an essential part of the visual system and the part of the brain responsible for object recognition.

In previous studies, researchers found that when subjects were shown a single, familiar image, their neurons responded less strongly than when they were shown an unfamiliar image. However, in the current study, the CNBC researchers found that when subjects were exposed to familiar and unfamiliar images in a rapid succession, their neurons — especially the inhibitory neurons — fired much more strongly and selectively to images the subject had seen many times before.

"It was such a dramatic effect, it leapt out at us," said Carl Olson, a professor at Carnegie Mellon. "You wouldn’t expect there to be such deep changes in the brain from simply making things familiar. We think this may be a mechanism the brain uses to track a rapidly changing visual environment."

Why are human faces so unique?

What’s in a face? The amazing variety of human faces — far greater than that of most other animals — is the result of evolutionary pressure to make each of us unique and easily recognizable, according to a new study out of UC Berkeley.

Behavioral ecologist Michael J. Sheehan explains that our highly visual social interactions are almost certainly the driver of this evolutionary trend. Many animals use smell or vocalization to identify individuals, making distinctive facial features unimportant, especially for animals that roam after dark, he said. But humans are different.

In the study, Sheehan and coauthor Michael Nachman asked, “Are traits such as distance between the eyes or width of the nose variable just by chance, or has there been evolutionary selection to be more variable than they would be otherwise; more distinctive and more unique?”

As predicted, the researchers found that facial traits are much more variable than other bodily traits, such as the length of the hand, and that facial traits are independent of other facial traits, unlike most body measures. People with longer arms, for example, typically have longer legs, while people with wider noses or widely spaced eyes don’t have longer noses. Both findings suggest that facial variation has been enhanced through evolution.

“Genetic variation tends to be weeded out by natural selection in the case of traits that are essential to survival,” Nachman said. “Here it is the opposite; selection is maintaining variation. All of this is consistent with the idea that there has been selection for variation to facilitate recognition of individuals.”

The origins of the 10% brain usage myth are unclear, they may have begun from a misquote of Albert Einstein, or misinterpretation of the works of the physiologist Pierre Flourens in the 1800s but the urban legend is still perpetuated in society today. There is no evidence to support this statement. We now know that even destruction of the tiniest parts of the brain could have serious impacts on a someone’s motor control and behavior(see Phineas Gage). This is why neurosurgeons have to carefully map out the brain before operation; to minimise as much damage as possible to our body’s most vital organ.

It is true, however, that we use 100% of our brain.

Creative Genius Driven by Distraction

Full article at NeuroscienceNews.com.

Research links creativity with inability to filter irrelevant sensory information.

The research is in Neuropsychologia. (full access paywall)

Research: “Creativity and sensory gating indexed by the P50: Selective versus leaky sensory gating in divergent thinkers and creative achievers” by Darya L. Zabelina, Daniel O’Leary, Narun Pornpattananangkul, Robin Nusslock, and Mark Beeman in Neuropsychologia doi:10.1016/j.neuropsychologia.2015.01.034

Sleep-Walking Neurons: Brain’s GPS Never Stops Working—Even During Sleep

Researchers at NYU Langone Medical Center have found that navigational brain cells that help sense direction are as electrically active during deep sleep as they are during wake time—and have visual and vestibular cues to guide them. Such information could be useful in treating navigational problems, among the first major symptoms of Alzheimer’s disease and other neurological disorders.

In a report on their work in mice to be published in the journal Nature Neuroscience online March 2, researchers found that head direction neurons continued to code for the “virtual” direction of their gaze during sleep. In fact, during Rapid Eye Movement (REM) sleep—a stage known for intense dreaming activity in humans and during which brain electrical activity is virtually indistinguishable from wake—the ‘needle’ of the brain compass in the mice surprisingly moved at the same speed than observed during wake. During slow-wave periods of sleep, it showed a 10-fold acceleration of activity, as if the mice turned their head 10 times faster than during the time they were awake.

“We have long known that the brain is at work during sleep,” says senior study investigator Gyorgy Buzsaki, MD, PhD, the Biggs Professor of Neural Sciences at NYU Langone and its Neuroscience Institute. “But now we know how it is working in one of the seemingly simpler senses—head orientation—or our sense of where we look at in any given space. The direction sense is an essential part of our navigation system, since it can reset our internal compass and maps instantaneously, as, for example, when we emerge from the subway and try to orient ourselves.”

He further adds: “Finding that the activity of head direction neurons shows coordinated patterns during sleep—as if substituting for the gaze shifts in the navigating animal—demonstrates the brain’s efforts to actively explore and coordinate its operations even when it disengages from its interactions with the environment.”

Buzsaki says the results further support his theory that brains in mammals do not passively wait around to receive sensory inputs, but actively pursue them, just like the active sense of head directionality persisted during sleep in the mice.

For the two-year study, researchers videotaped the head movements of mice and recorded the electrical activity in the head-direction regions of the sleeping animals, specifically in the antero-dorsal thalmic nucleus and postsibiculum regions of the brain. These recordings were then compared with similar readings made in the same mice while they were awake and navigating in various environments.

Adrien Peyrache, PhD, a postdoctoral fellow and lead author of the study, further concludes, “The coordinated activity during the majority of sleep likely represents a consolidation of places, events and times, a sort of navigational backup system in the brain, during which the brain stores a map to memory.”