Neuroscience

One in 10 individuals above the age of 65 develops an age-related neurological disorder like Alzheimer’s or Parkinson’s, yet treatment options for those patients remain sparse. Scientists have begun exploring whether cannabinoids—compounds derived from the cannabis plant, like well-known THC (tetrahydrocannabinol) and CBD (cannabidiol)—may offer a solution. A third, lesser-known cannabinoid called CBN (cannabinol) has recently piqued the interest of researchers, who have begun exploring the clinical potential of the milder, less psychoactive substance. In a recent study, Research Professor Pamela Maher, postdoctoral researcher Zhibin Liang, and colleagues explained how CBN protects the brain against aging and neurodegeneration, and used their findings to develop potential therapeutics.

Recalling each vocabulary word in a flashcard set faster with each flip through is evidence that our neural connections, called synapses, can grow stronger or weaker over time—a feature known as synaptic plasticity. Quantifying the dynamics of individual synapses can be a challenge for neuroscientists, but recent computational innovations from Professor Terrence Sejnowski, postdoctoral researcher Mohammad Samavat, and colleagues are changing that. To understand how the brain learns and retains information, scientists try to quantify how much stronger a synapse has gotten through learning, and how much stronger it can get. Synaptic strength can be measured by looking at the physical characteristics of synapses, but it is much more difficult to measure the precision of plasticity (whether synapses grow weaker or stronger by a consistent amount) and the amount of information a synapse can store. The new computational method can do all three, opening the door for new studies on human learning and memory and how those processes evolve or deteriorate with age or disease.

The human brain’s message-sending neurons can behave differently with age. At the root of these changes are shifts in the regulation of neuronal genes—how and when these cellular instructions are read can change the identity of individual neurons. This in turn changes the ratio of different neuronal cell types in the brain. Research Professor Margarita Behrens, Professor Joseph Ecker, Salk colleagues, and collaborators at UC San Diego looked at human frontal cortexes from young adult and aged donors and found widespread age- and sex-related variation in neuronal cell types: both the amount and type of neuronal cells changed with age. Cells in older frontal cortexes expressed fewer genes involved in the active message-sending function of neurons but expressed more subtelomere genes, which help protect the ends of chromosomes from age-related damage. Their findings describe changes in gene regulation in the aging human brain with unprecedented detail. This will ultimately help researchers understand what happens to brain cells in both healthy aging and age-related diseases like Alzheimer’s.