July 11, 2022 - Podcast

Episode 286 — Marijuana use during adolescence, and shrinking microchips

The legalization of marijuana in many states brings with it the greater possibility that younger populations will use it. Marijuana use during adolescence -- a critical period of brain development -- can impair working memory and increase the risk of psychosis later in life. Indiana University researchers are working to better understand the impact of cannabis use during adolescence, with a goal of developing therapies to treat its adverse effects in humans. IU neuroscientist Hui-Chen Lu says that today's cannabis strains are being bred for increased THC content, and it’s much riskier than the more traditional strains used in the past. Studies indicate that heavy use of cannabis with high THC -- particularly cannabis use that begins between ages 12 and 14 -- increases the risk of schizophrenia and other psychotic disorders from two- to five-fold, says IU researcher Ken Mackie. One of the functions of the prefrontal cortex is working memory, as well as processes like planning and impulse control, and that part of the brain is still developing in adolescence, he says. Developing brain structures are particularly vulnerable to environmental impacts, such as drug use or stress. Lu and Mackie have developed a new method to use mice to better understand the effects of cannabis use during adolescence. The researchers have chosen to work with mice with diverse genetic backgrounds to mimic human diversity. Unlike in past studies, they'll also be using both male and female mice to see if there are sex-dependent differences in THC effects. They will study the underlying molecular changes that account for behavior changes, like working memory deficits. They will also explore CBD because the consumption of marijuana may involve a mix of CBD and THC, and earlier research from IU Bloomington suggests that CBD might protect from THC's negative effects. The researchers will explore whether CBD has any harmful effects on its own and how it protects the developing brain from the adverse consequences of adolescent THC exposure. If cannabis disrupts prefrontal cortex development during the critical development period of adolescence, the impact can be huge and long lasting, Lu says, so it’s important to determine which therapies will work best based on a better understanding of what happens in the brains of young adolescents using cannabis.

In other news, microchips are everywhere, running computers and cars, and even helping people find lost pets. As microchips grow smaller, faster and capable of doing more things, the wires that conduct electricity to them must follow suit, but there's a physical limit to how small they can become. A team of physicists from IU and the University of Tennessee are working to solve this problem by designing a different system to accommodate ever-shrinking wires. In a traditional system, as you put more transistors on, the wires get smaller, says Paul Sokol, a physics professor at IU. Under newly designed systems, it's like confining the electrons in a one-dimensional tube, and that behavior is quite different from a regular wire, he says. The researchers used helium to create a model system for their study because its interactions with electrons are well known, and it can be made extremely pure, Sokol says. However, there were issues with using helium in a one-dimensional space, the first being that no one had ever done it before. The researchers nano-engineered a material by taking glasses that have one-dimensional channels and plating them with argon to coat the surface and make a smaller channel. They could then make samples that would hold a lot of helium and support the use of techniques like neutron scattering to get detailed information on the system. The researchers plan to next use this new model system to study helium at both high and low densities.