Just as promised, Leah Hanson lifted the red towel at the end of class.

See a Free Press photo gallery from the SCSC Science and Nature Conference.

And there it was for all to see: a real-life human brain.

“I’ve never seen a brain before,” said an incredulous Devon Tuma, a Montgomery-Lonsdale elementary student. “That was my favorite part.”

Suspended leisurely in an amber-colored preservative, its former shade of soft pink having faded into a ghostly gray, the donated organ was the undisputed showcase of South Central Service Cooperative’s Science and Nature Conference, held Tuesday at Gustavus Adolphus College.

Hanson, who is the director of the Alzheimer’s Research Center at Regions Hospital in St. Paul, used a brain donated anonymously to her research center to help present a session called “Brain Detectives.”

She talked about the various sections of the brain, as well as the five senses and how the brain perceives them. Students used red and green dots on folded paper to test their blind spots; they tasted seven different water solutions to test the sensitivity of taste receptors on their tongue.

For nearly an hour, Hanson covered the human brain from the sensory homunculus to the corpus collosum and back again — but all the while, she kept the centerpiece hidden.

But with a few minutes left before students shuffled on to their next destination, Hanson gave them what they were waiting to see.

Unveiling a large glass jar, she showed them where the corpus collosum joins the left and right hemispheres. She showed where the visual cortex sits at the rear of the brain. She even had some small sealed bags containing cross-sections of a brain for students to hold.

“We got to touch it,” said Eric Westland, who was among several students brave enough to give the brain matter a squeeze.

“It was really hard,” Tim Colwell added.

The Science and Nature Conference included 25 presentations given largely by area college faculty and industry experts.

Ron Spinosa, a past president of the Minnesota Mycological Society, taught students about growing their own edible oyster mushrooms in a roll of toilet paper and how the Reishi mushroom has been valued for centuries for its medicinal properties.

Jim Rife, a biochemistry instructor at Minnesota State University, gave a presentation on forensic science where students used the same methods seen on popular TV shows such as “CSI” to hash out a murder mystery.                                                                                                   

Diann Marten, a chemistry instructor at South Central College, showed students the properties of light by using “diffraction grating glasses” that show light in its rainbow pattern.

Julie Bartley, a geology professor at Gustavus, led a paleontology session where students examined fossils from several species and time periods — before having the opportunity to take one home.

As for Hanson and the donated brain? She said she was just happy it received such a warm welcome.“The kids seemed to be excited,” she said.