The Brain Organizes Objects by Size

Previously unknown to neuroscientists, how the brain organizes object representation or perceives and identifies different objects has been a mystery. A new study in Neuron, by MIT researchers, has discovered that the brain organizes objects based on their physical size, with a specific region of the brain reserved for recognizing large objects and another reserved for small objects.

According to the authors, It is “obvious that all objects in the world have a physical size, but the importance of this factor is surprisingly easy to miss when you study objects by looking at pictures of them on a computer screen.” How we interact with objects in the world is deeply and intrinsically tied to their real-world size, and this matters for how our brain’s visual system organizes an object. For example, we grasp small things with our fingers or we may use big objects to support our bodies.

Prior to this study, it was unknown whether the size of an object was an important factor in the brain’s ability to recognize it. By looking at the arrangement of the responses, they found a systematic organization of big to small object responses across the brain’s cerebral cortex. Large objects, they learned, are processed in the parahippocampal region of the brain, an area located by the hippocampus, which is also responsible for navigating through spaces and for processing the location of different places, like the beach or a building. Small objects are handled in the inferior temporal region of the brain, near regions that are active when the brain has to manipulate tools like a hammer or a screwdriver.

The study’s findings are also important for understanding how the organization of the brain has evolved and suggests that the human visual system’s method for organizing thousands of objects may also be tied to human interactions with the world. The work could have major implications for the field of robotics, in particular in developing techniques for how robots deal with different objects, from grasping a pen to sitting in a chair.

Neuron June 2012