How cannabis affects the human brain has been hotly debated, both by proponents of medical and recreational marijuana, and by its detractors. Research scientists may be the ones to answer all the questions we have about what this natural plant does to the brain in the short term and with long-term use. While research into cannabis in humans has been limited by legal restrictions, there have been some important studies in recent years that reveal some surprising new findings about the effects of cannabis :

1. Cannabis improves cognitive function.

There have been many claims that marijuana makes you less intelligent, even some studies claiming that adolescent users can expect to see a drop in IQ. More recent research, on the other hand, has found that in adults, smoking marijuana may actually increase executive function in the brain. The study, from Harvard, found that after three months of using medical marijuana, participants were better able to complete certain mental tasks. The researchers hypothesized that the medical marijuana relieved participants’ symptoms—anxiety, pain and others—and that this allowed them to better focus on tasks.

2. Cannabis reduces anxiety.

This was discovered in a study in which multiple sclerosis patients were given cannabis as an experimental treatment. Nearly all of the participants—89 percent—experienced a beneficial side effect: significantly less anxiety. The finding may be explained by how THC—the main psychoactive compound in cannabis—acts in the brain. It binds to cannabinoid receptors in the amygdala, the part of the brain most connected to anxiety and fear. According to studies with mice, when these receptors are activated, fear and anxiety are reduced.

3. Cannabis deactivates pain in the brain.

Pain relief is one of the main uses for medical marijuana and for good reason: it’s effective at altering our perception of pain. Research has found that most of the nerve cells in our body, which carry pain signals from distant parts of the body back to the brain, contain cannabinoid receptors. In fact, one region of the brain, called the periaqueductal gray region and that is a primary route for pain signals, has a higher concentration of cannabinoid receptors than other areas. Cannabis compounds bind to these receptors and block the pain signal going to the brain, effectively reducing pain.

4. Cannabis stimulates appetite through the brain.

This fact may not be that surprising, but science has found an explanation for it. The classic stereotype of a marijuana user is someone who always wants a snack, especially a sweet or fatty snack. There is truth to this stereotype, though. Researchers have found that when cannabis compounds activate cannabinoid receptors in the hypothalamus, it causes a release of the hormones leptin and neuropeptide Y. Both of these hormones stimulate appetite.

5. Cannabis can stop seizures in the brain.

One of the most seemingly miraculous effects of cannabis is in the treatment of children with a rare but severe seizure disorder. Anecdotal evidence has existed for years, but only recently researchers confirmed what some parents know: cannabidiol can significantly reduce seizures in some children. These kids have Dravet syndrome and suffer multiple seizures every week, sometimes multiple seizures in one day. Exactly how it works is not known, but cannabidiol seems to reduce the excitability of neurons in the brain, reducing seizures.

How cannabis affects the brain is multi-pronged. There is much more research to be done to determine all the many ways the multiple compounds in this plant act in the brain and what the results are for individuals. For now, we know that cannabis does have some very specific, and often useful, effects.