Throughout the past century, Cubs fans have been described as the best fans on Earth, boozy bleacher bums and sober baseball masochists, cockeyed optimists and eternal pessimists.

Aryeh Routtenberg, an expert on the brain, prefers to think of Cubs fans as being like mice.

"If you have an animal that touches a ball for food, and it gets fed every time he touches the ball, if the food stops, he'll stop right away," Routtenberg said. "But if you now change things to, every five guesses gets you a piece of food, the animal doesn't know what to expect. It's called a variable ratio, where the animal doesn't know when that food pellet is going to come. It's almost inextinguishable. The Cubs fan is almost like that. Throughout the seasons, they're loyal, and every now and again, hope is raised up to some level and then it decays, and then there's another win."

The avuncular Routtenberg, a neurobiology/psychology professor at Northwestern and self-avowed former Cubs fan (He declared any serious interest kaput after a particularly painful LaTroy Hawkins appearance in 2004), was one of the panelists earlier this month at a book release party at the Cubby Bear for "Your Brain on Cubs: Inside the Heads of Players and Fans," a look into the minds of sports fans and athletes by doctors, psychologists and medical experts who sometimes moonlight as baseball fans.

Routtenberg was a hit among the 80 or so in attendance at the Wrigleyville bar for the panel discussion on the book sponsored by the Illinois Science Council. At one point he livened up a fairly boring discussion by theorizing that a "toxic chemical" resides in the blades of grass at Wrigley Field and releases "negative karma" at crucial moments, like, say, in Game 6 of the 2003 National League Championship Series.

But half-baked theories like that aren't in the popular science book, which has seven chapters, written by 11 contributors, that link science and sports, from the mental reasoning behind superstitions to the neuroscience of hitting.

Despite the title, the book is not focused solely on the Cubs. It got its name from its editor, Dan Gordon, a longtime Cubs fan who had an epiphany at a game at Wrigley in 2004. Sitting in the bleachers during a break in a medical convention, he wondered why fans (like himself) kept coming back for more punishment, and what kind of joy they get out of loyalty to a team that wins so infamously and infrequently. While many fans would reach for another adult beverage when burdened by such weighty thoughts, Gordon started on this book.

Several themes that are addressed in the book are correlated to the Cubs, most memorably in the first chapter, "The Depths of Loyalty: Exploring the Brain of a Die-hard Fan." In this section, Jordan Grafman, a senior investigator for the National Institute for Neurological Disorders and Stroke, and a lifelong Cubs fan, explains why fans are loyal to "their" team and how their minds work in conjunction with their fandom. He has some good news for Cubs fans: They're better people than Yankees fans.

Grafman shares a theory that fans of perennially losing teams "turn out to be better decision-makers and deal better with divergent thought, as opposed to unreflective fans of winning teams such as those from New York City."

He theorizes that Cubs fans identify with the team in a personal way and use their devotion to bestow parts of their personality on it, and vice versa. This train of thought works especially well with people with identify themselves as "lovable losers."

In his chapter, Grafman clarifies that the Cubs fans' unyielding belief that every year is "next year" is attributed to activity in the prefrontal cortex, the region of the brain responsible for high-level cognitive activities, like planning, reasoning, establishing context and understanding of the infield fly rule (OK, just the first three).

The prefrontal cortex, the Mark DeRosa of brain regions, also is partially responsible for the joy fans get from experiencing Wrigley Field, because it controls the context of the trip. This region of the brain also controls our notion of self and links personal experiences to a broader context. For instance, Grafman notes that by watching the Cubs play at Wrigley Field, you are subconsciously reminded of playing games as a young child, and that makes you happy.

Grafman also observes that communal pride and a sense of belonging are linked with fans' devotion to both the Cubs and Wrigley Field. That line of thinking struck a chord with several fans in attendance at the Cubby Bear.

"That's absolutely true," said Stephanie Leathers, who has published a Cubs newsletter called the Bleacher Banter for the last 18 years. "We call [Wrigley Field] our home away from home. ... Cubs fans are different."

Leathers spoke during the discussion about the second family she has made in the bleachers and why that, almost as much as the baseball, keeps her coming back every year.

"The fact is, there is something very special about living in Chicago," Routtenberg said. "What is embodied [at Wrigley Field] doesn't happen in other baseball fields. There is a feeling that we're in it together."

But it's not just the sense of home that links fans and the Cubs. To some, being a Cubs fan is like being a fan of optimism.

"I think it's also, to a great extent, a sense of hope," said Al Cubbage, a longtime fan and the vice president of communications for Northwestern University. He attended the panel discussion with several of his friends. "Each year it is renewed, and you are hopeful that this year will be different than all other years that you will be successful. Last year, the Cubs won their division and it was remarkable re-affirmation of hope. There was no reason to expect it. The year before, they lost 98 games. So last year we had hope and the hope was realized."

And if that hope isn't realized this year, Routtenberg won't be too upset.

"What would happen if the Cubs win the World Series?" he said. "Of course everyone would be happy, but after the Red Sox won, there was something funny about them; they're not the same anymore. There's a sense of endowment and privilege. Someone once said suffering is the millstone that makes us special."