Noticing familiar objects in real world scenes: The role of temporal cortical neurons in natural vision

During natural vision, the brain efficiently processes views of the external world as the eyes actively scan the environment. To better understand the neural mechanisms underlying this process, we recorded the activity of individual temporal cortical neurons while monkeys looked for and identified familiar targets embedded in natural scenes. We found a group of visual neurons that exhibited stimulus-selective neuronal bursts just before the monkey's response. Most of these cells showed similar selectivity whether effective targets were viewed in isolation or encountered in the course of exploring complex scenes. In addition, by embedding target stimuli in natural scenes, we could examine the activity of these stimulus-selective cells during visual search and at the time targets were fixated and identified. We found that, during exploration, neuronal activation sometimes began shortly before effective targets were fixated, but only if the target was the goal of the next fixation. Furthermore, we found that the magnitude of this early activation varied inversely with reaction time, indicating that perceptual information was integrated across fixations to facilitate recognition. The behavior of these visually selective cells suggests that they contribute to the process of noticing familiar objects in the real world.