From cellular self-digestion to the effects of exercise on the brain, our features editor picks her favorite art custom-made for the magazine.

It’s no secret that exercise is good for the brain. In looking for mechanisms that could underlie such cognitive benefits, researchers have found evidence of neuronal growth and maturation and an increased volume of the hippocampus. At the molecular level, rodent experiments point to the demethylation of the promoter region of Bdnf, a gene that encodes the neurogenesis-boosting signaling factor of the same name. There’s even evidence that male mice can pass on the cognitive benefits of physical activity to their offspring through microRNAs carried in the sperm.

The channels of pain pathways

Disruptions in the way the voltage-gated sodium channel Na_V1.7 regulates the entry of sodium ions into sensory neurons can cause extreme pain—or eliminate it altogether. When the channel is overactive, pain-sensing neurons fire more, causing agony. When it is missing, people and animals are largely numb to pain. Researchers are now targeting the voltage-sensing domains of Na_V1.7 to achieve analgesia.

The multifarious nature of muscle aging

People start losing muscle mass as early as their 30s. Muscle stem cells decrease in number, possibly as a result of DNA methylation that accumulates on some genes involved in the self-renewal of these cells. Mitochondria in the muscles develop abnormal morphology, number, and function. Old muscles undergo less autophagy and make less protein. And some signaling factors known as myokines decrease with age. Luckily, exercise can reverse many of the physiological changes associated with muscle aging, so don’t forego your New Year’s resolution.

Full fish move to the back of the pack

Minnows swimming at the front of a school will eat until they’ve had their fill, then move to the back of the pack where swimming and navigating require less energy.

Macrophages both help and hinder tumor growth 

Immune cells called monocytes and tissue-resident macrophages that enter the tumor microenvironment are known as tumor-associated macrophages (TAMs). These cells can support cancer cell survival and dissemination through a number of mechanisms. But they can also protect the body against malignant disease. For example, TAMs can present cancer cell antigens to T cells and produce cytokines that boost antitumor immune responses. They can also phagocytose the tumor cells.

How the cell eats itself

Fresh discoveries in the field of autophagy are revealing how this process, by which a cell digests and recycles spent molecules and organelles, is linked to health and disease. There are a number of steps involved, from the formation of a vesicle precursor known as the phagophore to its maturation into an autophagosome and its subsequent fusion with a lysosome.

Insights into cholesterol regulation from rare disease

Familial hypercholesterolemia is a rare disease in which low-density lipoproteins (LDLs) are less likely to bind to cells in the body. This finding, from the 1970s, was the first indication that cells carried LDL receptors on their surfaces and laid the groundwork for researchers to subsequently discover how cholesterol derived from LDL regulates fatty molecule production.