Can brain stimulation improve memory?

 

Transcranial alternating current stimulation (brain stimulation) is a non-invasive method involving electrodes placed on the surface of the scalp. Brain stimulation of adults aged over 65 with weak electrical currents repeatedly over several days leads to memory improvements lasting for up to a month. Zapping the dorsolateral prefrontal cortex — a region near the front of the brain — with high-frequency electrical currents improved long-term memory. Stimulating the inferior parietal lobe, an area further back in the brain, with low-frequency electrical currents boosted working memory. Future studies will have to address whether the memory improvements can persist for longer than a month.

It also remains to be seen if treatment can help people with conditions such as Alzheimer’s disease.  

Read the article: Brain stimulation leads to long-lasting improvements in memory

Image by Gerd Altmann from Pixabay 

Copyright © 2022 by Eva Deli

Biological Age may be hidden in the DNA's "Epigenetic Clock"

 

In biological research, a clock for aging has been sought for a long time. Chronological age refers to the actual amount of time a person has been alive. Chronological age is the number of years a person has been alive. In contrast, biological age refers to relative aging, or life expectation, based on lifestyle factors and the predisposition to certain diseases.

In the nineteen eighties, researchers thought that telomeres might be the cell's clock's mechanism because telomeres, DNA-protein complexes at the ends of chromosomes, shorten each time a cell divides. Furthermore, the correlation of telomere length with age and mortality was thought to be related to age; when telomeres become critically short, cells die. However, scientists learned that telomere length does not track age.

The anti-aging researcher Steve Horvath has developed computational clocks that can estimate the biological ages of organisms and tissues from methylation patterns in their DNA. He found that biological age refers to epigenetic alteration and DNA methylation, which express a person's ability and functioning and whether she has diseases related to old age. Epigenetic modification alters the expression of the gene rather than the genetic code itself. It changes the chemical tags called methyl groups that hang on DNA and help control gene activity. 

The epigenetic age can differ from the biological age. Researchers discovered that when the epigenetic clock estimated that someone's age was greater than their chronological age, they faced a higher risk of disease and death. When the clock showed that someone was younger, their risk went down. Even though the epigenetic clock was derived from chronological age data, its algorithm predicted mortality better than age did. The methylation clocks may be the most accurate monitors of biological age today. 

Read the article in Nature, The relationship between epigenetic age and the hallmarks of aging in human cells.

Image by Edgar Romero 

Copyright © 2022 by Eva Deli

Why does extended cognitive demand compromise decision-making ability?

 

A new study examined the cognitive burden of mentally taxing assignments. The study examines the metabolic changes in the brain during exhaustion, thereby linking mental fatigue with neurometabolism. Participants working long hours on challenging projects had higher levels of glutamate in the brain's prefrontal cortex by the end of the day than those with more manageable tasks. Glutamate is an essential signaling molecule in the brain, but its accumulation can disrupt brain function.

At the end of the workday, exhausted people are likelier to opt for short-term, easy solutions than meaningful rewards that require a longer wait or involve more effort. Therefore, rests are necessary to restore the proper level and regulation of the molecule.

How does the recovery of glutamate occur in the brain? Some studies indicate that glutamate concentrations decrease during sleep, proportional to EEG slow-wave activity. It is speculated that the extracellular glutamate may be cleared during rest or sleep.

Read more: Wiehler, A., Branzoli, F., Adanyeguh, I., Mochel, F. & Pessiglione, M. Curr. Biol. https://doi.org/10.1016/j.cub.2022.07.010 (2022).

Photo by Ephraim Mayrena on Unsplash

Copyright © 2022 by Eva Deli