Reference frame coding in primate frontal cortex

点击翻译按钮获取中文摘要

BACKGROUND: Our daily behavior involves the transformation of visual information into motor commands for the muscles that execute our actions. This visual-to-motor transformation requires mapping visual signals entering the retinas in an eye-centered reference frame into motor actions executed in other frames relative to body parts (e.g., head, body). The neural mechanisms underlying such reference frame transformation are not well understood. We have previously hypothesized that a cortical area of the frontal lobe, the Supplementary Eye Fields (SEF), in which visual and motor information coexist, performs the transformation, however this hypothesis has not been tested. OBJECTIVES: The experiments proposed here will test this hypothesis. The proposal has two main aims. First, to investigate whether during gaze shifts different neurons within the SEF encode visual and motor information in different reference frames as well as the temporal dynamics of reference frame coding within these neurons. Second, to determine whether SEF neurons perform reference frame transformations for different motor systems (i.e., gaze and arm movements). SCIENTIFIC APPROACH: We will measure eye and head movements in 3D of alert (head unrestrained) monkeys trained to perform two different tasks: a) to make gaze shifts toward a visual target from a fixation spot, and b) to signal the position of a target by touching a screen while keeping gaze on a fixation spot. By dissociating the initial eye, head and body pointing directions and recording neuronal responses using electrode microarrays implanted on the SEF cortical surface, we will determine the reference frame and temporal dynamic of neuronal activation within the area in both tasks. This should reveal whether reference frame transformations occur in the SEF. SIGNIFICANCE: The results of this project could be relevant to rapidly advancing fields such as neural motor prosthesis, since they will provide insight into how motor actions are encoded in the primate frontal cortex. Our results could also be used to build computational models of visuomotor transformations that will contribute to understanding the neural basis of motor control.