Sunday, May 14, 2017

Highlights and new discoveries in Neuroscience (April 2017)

In the latest edition of this monthly digest series you can learn how your brain activity changes under the influence of psychedelic drugs, why brain games won't actually make you smarter, and how gene therapy might be able to treat patients blinded from retinitis pigmentosa.


First evidence for higher state of consciousness

Researchers from the University of Sussex have observed a sustained increase in neural signal diversity - which is a measure of the complexity of brain activity - of people under the influence of psychedelic drugs (such as ketamine, LSD, and psilocybin), compared to a normal waking state.

The diversity of brain signals provides a mathematical index of the level of consciousness. For example, people who are awake have been shown to have more diverse neural activity using this scale than those who are asleep.

This, however, is the first study to show brain-signal diversity that is higher than baseline, that is higher than in someone who is simply ‘awake and aware’. The team say that more research is needed using more sophisticated and varied models to confirm the results but they are cautiously excited.

Professor Anil Seth, Co-Director of the Sackler Centre for Consciousness Science at the University of Sussex, said: “This finding shows that the brain-on-psychedelics behaves very differently from normal. “During the psychedelic state, the electrical activity of the brain is less predictable and less ‘integrated’ than during normal conscious wakefulness – as measured by ‘global signal diversity’. “Since this measure has already shown its value as a measure of ‘conscious level’, we can say that the psychedelic state appears as a higher ‘level’ of consciousness than normal – but only with respect to this specific mathematical measure.”

This does not mean that the psychedelic state is a ‘better’ or more desirable state of consciousness, the researchers stress; instead, it shows that the psychedelic brain state is distinctive and can be related to other global changes in conscious level (e.g. sleep, anaesthesia) by application of a simple mathematical measure of signal diversity. The research team are now working hard to identify how specific changes in information flow in the brain underlie specific aspects of psychedelic experience, like hallucinations.

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Think brain games make you smarter? Think again

Be skeptical of ads declaring you can rev up your brain’s performance by challenging it with products from the growing brain-training industry. Science does not support many of the claims.

A new study reveals antidepressant use during early pregnancy does not increase the risk for the offspring developing ADHD or autism, as previous studies suggest. However there was a slight increase in the risk of premature birth associated with antidepressant use during the first trimester. (via NeuroscienceNews)

That is according to a new study by researchers from Florida State University (FSU). “Our findings and previous studies confirm there’s very little evidence these types of games can improve your life in a meaningful way,” said Wally Boot, Associate Professor of Psychology, an expert on age-related cognitive decline. “More companies are beginning to be fined for these types of inflated claims and that’s a good thing,” Boot said. “These exaggerated claims are not consistent with the conclusions of our latest study.”

The FSU team focused on whether brain games could boost the “working memory” needed for a variety of tasks. In their study, they set up one group of people to play a specially designed brain-training video game called “Mind Frontiers,” while another group of players performed crossword games or number puzzles. All players were given lots of information they needed to juggle to solve problems. Researchers tested whether the games enhanced players’ working memory and consequently improved other mental abilities, such as reasoning, memory and processing speed.

The short answer is: no. While it's possible to train people to become very good at specific tasks, such as the specific game they're playing, the perceptual learning literature suggests that these skills do not necessarily transfer to other tasks. “If I can get very good at crossword puzzles, is that going to help me remember where my keys are? And the answer is probably no.”

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Study overturns seminal research about the developing nervous system

New research by scientists at the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA overturns a long-standing paradigm about how axons — thread-like projections that connect cells in the nervous system — grow during embryonic development.

It has been long been known that various guidance cues, which are cellular molecules such as proteins, either attract or repel axon growth as the axons reach out from neurons to find their destination in the nervous system. One such guidance cue comes in the form of netrin1, which is produced by tissue-specific stem cells in the embryonic spinal cord. The new study offers a significant reinterpretation of how netrin1 works: Instead of functioning over a long distance to attract and organize axon growth (much like a lighthouse sends out a signal to orient a ship from afar), netrin1 instead directs axons only in their local environment, acting as a sticky surface that encourages axon growth in the direction that form a normal, functioning nervous system.

Determining how netrin1 specifically influences axon growth could help scientists use netrin1 to regenerate axons more effectively in patients whose nerves have been damaged.

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Miscellaneous

Using the gene-editing tool CRISPR/Cas9, researchers at University of California San Diego School of Medicine and Shiley Eye Institute at UC San Diego Health, with colleagues in China, have reprogrammed mutated rod photoreceptors to become functioning cone photoreceptors, reversing cellular degeneration and restoring visual function in two mouse models of retinitis pigmentosa. (via NeuroscienceNews)

Researchers propose that the world-famous painter Francisco Goya may have suffered from Susac’s syndrome, a rare autoimmune disease that robbed him of his hearing. A second possibility is syphilis. (24th Annual Historical Clinicopathological Conference)

Researchers from France and the University of Arkansas have created an artificial synapse capable of autonomous learning, a component of artificial intelligence. The discovery opens the door to building large networks that operate in ways similar to the human brain. (via NeuroscienceNews)

According to a new study from the Boston University School of Medicine, consuming more than one sugar beverage per day (e.g., soda, fruit juice) is associated with accelerated brain aging, smaller hippocampal volume and poor memory. (Alzheimer's & Dementia)

A newly discovered molecule increases appetite during fasting — and decreases it during gorging. The neuron-exciting protein, named NPGL – apparently aims to maintain body mass at a constant, come feast or famine. An evolutionary masterstroke, but not great news for those looking to trim down — or beef up for the summer. (via NeuroscienceNews)

A new study reveals the amygdala has distinct neurons that can judge ambiguity and intensity of facial expressions. One group, the emotion-tracking neurons, detects the intensity of a single specific emotion, such as happiness or fear. The other group, the ambiguity-coding neurons, indicates the ambiguity of the perceived emotion, irrespective of the nature of that emotion. (via NeuroscienceNews)

Yoga can reduce pain and enhance mood for women suffering from a range of menstrual disorders, a new study reports. (Journal of Alternative and Complementary Medicine)

Columbia scientists have identified a gene that allows neurons that release serotonin — a neurotransmitter that regulates mood and emotions — to evenly spread their branches throughout the brain. Without this gene, these neuronal branches become entangled, leading to haphazard distribution of serotonin, and signs of depression in mice. (via NeuroscienceNews)

Researchers from the University of Edinburgh have discovered a group of neurons in the retina that affect circadian rhythm by sending signals to the suprachiasmatic nucleus (SCN). This gives an insight into how the biological clock is regulated by light and could open up new therapeutic opportunities to help restore altered circadian rhythms through the eye. (Journal of Physiology)