Scientists Discover Concept Cells for "Nest" in the Mouse Brain

March 27, 2007

A team of researchers led by Boston University School of Medicine (BUSM) neurobiologist Joe Z. Tsien, PhD, report they have identified brain cells in mice that are involved in the encoding of the concept of “nest” or “bed.” The discovery, published in this week’s early edition of National Proceedings of Academy of Sciences, provides crucial insight into how the brain generates concepts and abstract knowledge from daily experiences.

The ability to form abstract concepts and knowledge is believed to be one of the exclusive hallmarks for humans and perhaps, other primates, and is essential for guiding behaviors in dealing with novel and complex situations. For example, when we check into a hotel, the concept of ‘bed’ in our brains helps us identify the bed effortlessly among other various pieces of furniture in the room although the bed could be quite different from the one at our home.

To study how the brain encodes abstract concepts, the scientists investigated whether and how mice would recognize nests or beds. Tsien and his colleagues found that cells in the hippocampus, a region in the brain important for processing memory, selectively fire or cease to fire when the mouse perceives nests, regardless of their physical shape, style, color, odor, or construction materials. They further found that the abstract encoding of conceptual knowledge/awareness of nests is based on the functionality of nests, requiring physical explorations to determine the functionality of the objects.

According to Tsien, the nest cells would not respond to the nest if it were covered by a piece of glass, or if the nest were placed upside-down. This suggests that conceptual categorization of those objects is defined by the practicality and functionality of these items.

“This makes good sense since even a piece of flat rock can function as either a chair or table, depending upon its height or whether it is viewed from the perspective of a small child or an adult,” said Tsien, director of the Center for Systems Neurobiology in the Department of Pharmacology & Experimental Therapeutics at BUSM, and a joint professor in the Department of Biomedical Engineering at Boston University.

This study further illustrates that the memory system is an intrinsic part of the hierarchical architectures engaged in extraction, processing, and representation of abstract concepts and knowledge from daily behavioral experiences.

The first author of the paper is Dr. Longnian Lin, a former post-doctoral fellow in Tsien’s lab and now an associate professor at the Shanghai Institute of Brain Functional Genomics at East China Normal University in Shanghai. Authors Guifen Chen, Hui Kuang and Dong Wang, are currently graduate students in Tsien’s lab.

Source: Boston University