La Jolla, CA Every kid knows that moms have eyes in the back of their heads. We are adept at fixing our gaze on one object while independently directing attention to others. Salk Institute neurobiologists are beginning to tease apart the complex brain networks that enable humans and other higher mammals to achieve this feat.
In a study published in the July 5, 2007 issue of Neuron, the researchers report two classes of brain cells with distinct roles in visual attention, and highlight at least two mechanisms by which these cells mediate attention. This study represents a major advance in our understanding of visual cognition, because it is the first study of attention to distinguish between different classes of neurons, says system neurobiologist John Reynolds, Ph.D., associate professor in the Systems Neurobiology Laboratory at the Salk Institute.
In the experiments, animals learned how to play a sophisticated video game, which challenged their visual attention-focusing skills. During the game, the Salk researchers recorded electrical activity from individual neurons in part of the visual cortex that has been implicated in mediating visual attention. (Please see video.)
As illustrated in the demonstration, the neurons respond when a stimulus appears within a window (indicated by the circle) covering a small part of the visual field that the eye sees. This window is known as the neurons receptive field. Whenever the stimuli entered the neurons receptive field, the cell produced a volley of electrical spikes, known as action potentials, indicated by vertical tick marks in the demonstration.
On some trials, attention was directed to the stimulus that entered the neurons receptive field, while on other trials attention was instead directed to the other stimuli. The researchers recorded almost 200 differe
Contact: Gina Kirchweger