Charles Zucker fires lasers into brains to trigger sweetness

Sweetness is an illusion created entirely inside the human brain.

Food scientists long believed chemical potency was the key to replacing sugar. Synthetic compounds like lugduname activate taste receptors at hundreds of thousands of times the potency of table sugar. Yet high potency rarely translates to intense flavor. On Radiolab in September 2026, Rutgers professor Paul Breslin explained that human sweetness receptors act like dimmer switches with strict intensity ceilings.

Artificial molecules hit that ceiling almost immediately while frequently triggering bitter receptors that ruin the taste. Natural sugar wins because human evolution wired neural reward systems directly to glucose. When host Latif Nasser fed the high-potency compound adventame to his children, they gagged instead of enjoying it.

If chemical potency fails, multisensory hacks offer a temporary workaround. Psychologist Linda Bartoshik pointed out on the show that volatile odor molecules pushed into the nasal cavity during chewing boost sweetness signals inside the cortex. Visual cues like red dye and auditory frequencies like high-pitched tones trick the brain into anticipating sweetness, boosting perceived intensity by up to 10 percent without extra calories.

The real frontier skips the tongue altogether. Columbia University neurobiologist Dr. Charles Zucker mapped the exact neural pathway sweet signals travel from the tongue through the thalamus to the cortex. By engineering mice to express light-sensitive proteins in their sweet-sensing cortical neurons, Zucker demonstrated that firing a fiber-optic laser directly into the brain triggers pure sweetness without food present.

Direct neural activation circumvents every physical receptor limit built into human biology. A targeted beam of light creates an intense sensation of sweetness that no physical molecule can replicate.

Physical sugar may soon become obsolete.