What if we could use brain waves to treat Alzheimer's? Professor and neuroscientist Li-Huei Tsai details a promising new approach to artificially stimulate gamma brain waves using light and sound therapy, to increase connectivity and synchrony and delay the onset of this deadly disease. This non-invasive therapy has already been shown to work in mice -- now it's on to human clinical trials, with the potential to usher in a brighter future for everyone. (Followed by a Q&A with head of TED Chris Anderson)

Dinosaur tracks can teach us more about the day-to-day behavior of creatures like T. rex or the Stegosaurus than their skeletons ever could, says paleontologist Martin Lockley. From a "dinosaur's lover's lane" in Colorado to the rocky shores of South Korea, Lockley explores what we can learn from the traces of some of the most impressive creatures ever to walk the Earth.

Could the next wonder drug be somewhere in Canada's snowy north? Take a trip to this beautiful, frigid landscape as chemist Normand Voyer explores the mysterious molecular treasures found in plants thriving in the cold. These scarcely investigated organisms could hold immense medical promise, he says – so long as we work quickly enough to discover them.

In the US, youth in foster care are nearly twice as likely as war veterans to suffer from PTSD. Placed in foster care at just 11 months old, 2023 Audacious Project grantee Sixto Cancel experienced the faults of the system firsthand. Now, he's the founder of Think of Us, an organization working to reform child welfare by centering kinship care, or placing a child with an extended family member or a familiar adult. Learn more about his plan to help thousands of kids searching for a loving home with one simple, systemic switch. (This ambitious idea is a part of the Audacious Project, TED's initiative to inspire and fund global change.)

Lots of people talk about the need to be physically fit, but mentally fit? Not as much. In a powerful talk, mental health advocate Gus Worland shares how an experience of deep grief from his own life sparked his mission to advocate for suicide prevention -- and shows why "looking after your own village" can be as simple as sending a text message, right now, to the person you cannot imagine living without.