The mind of a human may be complex, but Pat Sharp’s research has figured out one of its nearly infinite functions: How do we know which way we’re going?
Sharp, who spoke last night in the Student Union Theater, studies head direction cells — neurons that give mammals a sense of direction.
People whose head direction cells were damaged in accidents couldn’t tell east from west afterward, even when near familiar landmarks, according to Sharp.
“One block away from their house, you could ask them, which way is your house?” she said. “They would not know.”
As part of the study, Sharp and her colleagues placed thinner-than-hair wires into the brains of live rats, which are similar to humans when it comes to perception of direction.
These wires, placed between the neurons that detect direction, were hooked to speakers. Whenever a rat faced a particular direction — east, for example — an electric charge would shoot between the neurons, causing the speakers to buzz.
“Neurons (store energy) like any battery you can buy at Radio Shack,” Sharp said.
She and her colleagues placed a wired rat into a small container with a white card on one side — the neurons would pick a direction at random, firing only when the rat faced that way. However, when they disoreinted the rat and moved the card, the neurons were tricked to fire when the rat faced a different way.
This means that a single group of cells lets humans and other mammals know which way they’re facing, even when their eyes are closed, according to Sharp.
“It tells us that, if you’re facing west and haven’t turned your head, you’re still headed west,” she said.
The research also helps disprove the idea that mammals use their cells like tiny compasses, detecting magnetism from the planet’s poles to sense direction.
“That’s just not the case,” Sharp said.
The idea that a rat’s brain activity can be predicted has sparked philosophical debate, even when that activity concerns something as simple as direction.
The notion that any thoughts could be predicted draws the concept of a human’s free will into question, according to Sharp.
Even if human thought could be simplified to reactions between cells, the brain’s billions of intertwined neurons create a network of thought so complex that predicting someone’s actions will probably always be impossibly complex, Sharp said.
“Anyone who has teenagers around the house is well in touch with this,” she said.
A few teenagers were actually in the audience, as the presentation was aimed at both the scientist and the lay-person. It was part of the A ‘ S Distinguished Faculty Lecture Series, which is targeted at a general audience, according to Donald Nieman, dean and professor of history in the college of arts and sciences. Though the presentations aren’t just for scientists, experts in the field could still learn something from Sharp and the other speakers in the series. Presenters are among the best researchers at the University, according to Nieman.
He was particularly impressed with Sharp’s accomplishments, which include 30 published articles and a book, he said before introducing her.
“I was prepared to be impressed when I saw her resume, but, my God, it was just extraordinary,” Nieman said.
Sharp has studied at universities across the nation, including Yale, where she started researching Head Directional Cells in 1990. She came to Bowling Green in September 2001, where she continues her research.
How that research might be used in the future is for the most part a mystery to Sharp. But, for now, Sharp is content just to know more about the brain.
“We can replicate the behavior of cells,” she said. “Thereby, we can explain one component of consciousness.”
