Barry Green and a team of researchers are mixing up drinks at the John B. Pierce Laboratory with the hopes of gaining a greater understanding of brain function.

The study, funded by the National Institutes of Health, is currently focusing its efforts on two major projects — studying the relationship between temperature sensitivity and pain, and investigating oral sensations and taste. Green, a professor at the Yale School of Medicine, said the intent of the research is to gain a deeper understanding of basic temperature, taste and pain mechanisms.

“The overarching theme that guides my research is that human sensory perception cannot be understood in terms of the classical five senses alone,” he said. “That’s been the way it has traditionally been pursued.”

Green said the interesting aspect of the temperature and nociception, or pain, study is that it does not focus on pain alone, but on the interactions between pain and temperature. The research’s goal is to determine the relationship between pain perception and neurons in the skin which detect hot and cold stimuli.

Hannah Collins ’06, the project’s only undergraduate research assistant, is determining how local skin sensitivity affects an individual’s reaction to temperature.

“We look at how different areas of a person’s skin respond according to what neurons and what sensors are in the area,” Collins said. “Two different people may have the same overall perception of cold or of a certain temperature, but if we zoom in on more specific areas of their skin, the two people might feel things very differently.”

Pierce Laboratories also houses research determining the relationship between taste and other oral sensations, including temperature and pain. These studies are conducted on human subjects using noninvasive, psychophysical methods. Subjects are exposed to stimuli — such as tasting a citric solution — under controlled conditions and then required to give responses according to the sensations experienced. Factors such as the temperature of the solution are then varied, and the differences in observed effects are analyzed.

“When we put something in the mouth, we stimulate more than just a sense of taste,” Green said. “We stimulate touch and temperature. One of the questions that is still unanswered is how the input from these various stimulations interact to give us the sensation of taste.”

The primary goal of Green’s research is to obtain a better understanding of brain function and the basic, underlying relationship between different sensory perceptions.

According to Kate Schoen, a full-time research assistant involved with thermal and nociceptive research, humans typically take the relationship between temperature and pain for granted. This research could offer a scientific interpretation for everyday sensations that impact personal comfort and well-being.

“In one sense, it’s basic research, which means that we’re doing our research just to gain knowledge about how the brain works and how we perceive different sensations,” Schoen said. “And so I think in that sense it’s just a way to have a better understanding of how the mind works and how we function.”

Oral and cutaneous sensitivity research has clinical applications. People who suffer from congenital insensitivity to pain with anhidrosis — a genetic disorder which renders the individual unable to feel pain — cannot detect situations that may be dangerous to their health. For example, they do not feel heat from stoves or fires, and they do not feel the impact of a hard fall or hit. Schoen said the understanding gained from research in the oral and cutaneous sensitivity laboratory has the potential to affect the study and treatment of this and similar disorders.