Pulvinar regulates communication between clusters of brain cells

"For our study, we trained monkeys to play a video game in which they paid attention to visual cues in order to detect different target shapes. We simultaneously recorded brain activity in the pulvinar and two different areas of the visual cortex. We could see a clear connective path from one portion of the cortex to another, as well as connective paths from the pulvinar to the cortex. When the monkeys paid attention to the visual cues, the pulvinar sent electrical pulses to synchronize particular groups of brain cells in the visual cortex to allow them to communicate effectively.

"A challenge in this study was that we needed to record the activity of cells that were 'speaking' directly with each other so we could trace the line of communication. But there are billions of brain cells. Traditionally, finding a cell-to-cell connection is as likely as randomly selecting two people talking on cell phones in different parts of New York City and discovering that they were speaking to each other.

"To 'listen in' on a direct cell conversation, we developed a new approach of using electrodes to record groups of brain cells that were anatomically connected. We first mapped neural connections in the brain via diffusion tensor imaging, which uses an MRI scanner to measure the movement of water along neural connections. We then used these images to implant electrodes at the endpoints of the neural connections shared by the pulvinar and the visual cortex.

"Our mapping of these communication networks and our finding that the pulvinar is vital to attention prompts a new consideration of the mechanisms behind higher cognitive function. We challenge the common notion that these functions depend exclusively on the cerebral cortex, the outermost layer of the brain responsible for decision-making, attention and language, among other abilities. It also suggests that the prevailing view that visual information is transmitted solely through a network of areas in the visual cortex needs to be revised to include the pulvinar as an important regulator of neural transmission."

Source: Princeton University