science

Exercise pumps up your muscles — but it might also be pumping up your neurons. According to a study published today in Neuron, repeated exercise sessions on a treadmill strengthen the wiring in a mouse’s brain, making certain neurons quicker to activate. This ‘rewiring’ was essential for mice in the study to gradually improve their running endurance.

Betley and his colleagues[...] decided to focus on the ventromedial hypothalamus, a brain region that regulates appetite and blood sugar. The team then zeroed in on a group of neurons in that region that produce a protein called steroidogenic factor 1 (SF1), which is known to play a part in regulating metabolism. A previous study found that the deletion of the gene that codes for SF1 impairs endurance in mice.

Betley’s team monitored the activity of SF1 neurons in mice running on a treadmill and found that these cells were indeed activated by exercise. Interestingly, one group of SF1 neurons became active only after exercise sessions ended. After several training sessions, the number of neurons that were activated post-run, as well as the magnitude of their activation, increased.

When the researchers examined brain slices from mice that had trained consistently over three weeks, they saw changes in the SF1 neurons’ electrical properties compared with mice that had not repeatedly exercised. These changes indicated that the neurons in the trained mice had become easier to activate. They also found that repeated exercise doubled the number of synapses — connections between the neurons — that were ‘excitatory’, or primed to fire off an electrical signal.

Finally, the authors used optogenetics — a technique that can activate or inhibit genetically engineered neurons with light — to ‘switch off’ SF1 neurons in the mice after they exercised. When these neurons were turned off, the mice didn’t improve their running performance over time, becoming exhausted more quickly than mice in which SF1 neurons were not switched off.

The research article itself (open access): Kindel et al.. Exercise-induced activation of ventromedial hypothalamic steroidogenic factor-1 neurons mediates improvements in endurance. Neuron. URL link. The graphical abstract does a very good job of explaining the research

The Trump administration on Thursday revoked a scientific finding that long has been the central basis for U.S. action to regulate greenhouse gas emissions and fight climate change, the most aggressive move by the Republican president to roll back climate regulations.

The rule finalized by the Environmental Protection Agency rescinds a 2009 government declaration known as the endangerment finding that determined that carbon dioxide and other greenhouse gases threaten public health and welfare. The Obama-era finding is the legal underpinning of nearly all climate regulations under the Clean Air Act for motor vehicles, power plants and other pollution sources that are heating the planet.

The repeal eliminates all greenhouse gas emissions standards for cars and trucks and could unleash a broader undoing of climate regulations on stationary sources such as power plants and oil and gas facilities, experts say. Legal challenges are near certain.

Ocean warming is increasing the frequency, extent, and severity of tropical-coral bleaching and mortality. During 2014–2017, marine heatwaves caused the Third Global Coral Bleaching Event. We analyze data from 15,066 reef surveys globally during 2014–2017. Across all surveyed reefs, 80% and 35% experienced moderate or greater (affecting >10% of corals) bleaching and mortality, respectively.

We assess the global extent of coral bleaching and mortality by applying bleaching response curves calibrated from surveyed reefs to predict bleaching globally, based on comprehensive remote-sensing of heat stress. These models predict that 51% and 15% of the world’s coral reefs suffered moderate or greater bleaching and mortality, respectively, during one or multiple years, surpassing damage from any prior global coral bleaching event. Our findings demonstrate that the impacts of ocean warming on coral reefs are accelerating, with the near certainty that ongoing warming will cause large-scale, possibly irreversible, degradation of these essential ecosystems. With heat stress levels during this event surpassing those observed previously, the National Oceanic and Atmospheric Administration developed more extreme Bleaching Alert levels that are now being used during the ongoing Fourth Global Coral Bleaching Event.

I think the most important remaining scientific question is whether this will give rise to pigra or pigzilla.

https://archive.md/KBCis

Some cuts from the article:

They found that individuals with very short sleep, high inactivity and low moderate to vigorous activity had the highest rates of dementia and evidence of accelerated brain ageing on MRI.

How to stave off dementia when you’re a short sleeper

To figure out your optimal ratio, we should start with a baseline understanding of our sleep.

For instance, are you a short sleeper (who gets less than six hours of sleep) or a normal sleeper (who gets between six and nine hours)?

If you’re a short sleeper, the study found that increasing sleep duration was associated with a lowering of dementia risk when at the expense of inactivity or light activity, but not when at the expense of moderate to vigorous physical activity.

Specifically, increasing sleep by 30 minute instead of engaging in inactivity or light activity was associated with a 9 per cent and 19 per cent reduction in dementia risk, respectively.

A key technique of cognitive behavioral therapy for panic disorder is interoceptive exposure, where patients learn to tolerate the physical effects of panic attacks through repeated simulated exposure. Now, scientists have shown in a randomized controlled trial that brief intermittent intensive exercise is more effective at reducing the severity of panic disorder than relaxation therapy.