The primary visual cortex (BA 17) encodes elementary features of visual stimuli such as local contrast, spatial location, spatial frequency, orientation, and ocularity (Hubel, 1982). An extensive body of work has shown that the representation of these basic visual features can be significantly modulated by attention as well as the association of stimuli with reward. Both attention and reward are thus potential candidates for mediating the effect of drug cues on visual cortical activity.
