Classical views of information flow in primary visual cortex suggest that orientation information is encoded early in a feedforward architecture and passed to higher levels of cortex for further processing. More recent studies suggest that top-down information can modulate processing of even basic visual attributes. We investigated whether responses in primary visual cortex are modulated by top-down effects evoked by differential rewarding of oriented grating stimuli. Multiunit extracellular recordings were obtained using a microwire electrode array chronically implanted in rat primary visual cortex while grating stimuli were presented under different reward conditions. An awake headfixed animal viewed alternating +45° and -45° sinusoidal grating stimuli. During a control sessions, gratings were passively presented with no reward. In three subsequent sessions, one grating (CS+) was paired with a water reward while the other grating (CS-) remained unrewarded. On the third rewarded session, units showed a two-fold increase in firing that plateaued and then returned to baseline during the CS+, while firing rates for the CS- remained relatively constant across sessions. In addition, coherence among units reflected timing of an expected visual stimulus change. These results suggest a more complex model of visual processing where topdown contextual information strongly and continuously influences stimulus-specific bottom-up processes at even the earliest stages of visual processing.