Abstract
In order to shift gaze the visual system first identifies the location of an object in the visual scene and then directs the eyes accordingly. Therefore, the neural responses signaling the perception of the object need to be coupled to motor activity. Here we studied the role of the primary visual cortex in the integration of visual and motor processes.
We tested two monkeys (Macaca Mulatta) in a figure-ground detection task. Animals fixated a small dot on the center of the monitor where a textured figure-ground stimulus appeared. The animals maintained fixation until cued to saccade towards the figure location. During this task, we recorded multi-unit activity of neurons in the primary visual cortex. When the figure was overlying the receptive fields (RFs), responses to ‘figure’ were recorded, or else the background covered the RFs (‘ground’ responses). Previously we have shown that the responses to ‘figure’ are enhanced relative to the responses to ‘ground’. This modulated activity (figure-ground response) is the neural correlate of the perception of the figure.
We show that ∼100ms before the onset of the saccade the figure-ground response starts to increase. This pre-saccadic response enhancement is stronger when the saccade is directed towards the position of the recorded RFs compared with the situation when the saccade is directed away from the RFs. This difference is not related to the RFs stimulus (i.e. ‘figure’ or ‘ground’). In addition, the strength of the figure-ground response, before its pre-saccadic enhancement, correlates with the reaction time. Thus, the strength of the figure-ground activity predicts the moment of the saccade onset.
These observations indicate that the figure-ground responses include saccade related activity. We propose that the primary visual cortex participates in the coordination of perception and oculomotor behavior.