The two studies reviewed above, in addition to our own work, provide evidence that motivation modulates fronto-parietal regions involved in attention. Additional evidence also supports the modulation of sensory cortex by motivation. For instance, Pantoja et al. (2007) investigated neuronal responses in the rat primary somatosensory cortex (S1) during a tactile discrimination task. Stimulus-related information encoded by S1 neuronal ensembles increased when the contingency between stimulus and response was crucial for reward, but not when reward was freely available. In addition, stimulus-related information was directly related to behavioral task performance. Related neuroimaging findings in humans were reported by Pleger et al. (2008, 2009), who used a tactile discrimination task coupled with financial rewards awarded for correct performance at the end of each trial. While reward improved discrimination performance and concordantly enhanced activity in the ventral striatum, the effect of reward on somatosensory responses was only observed in a post-stimulus phase between stimulus offset and reward delivery. Interestingly, the increase in somatosensory cortex responses varied parametrically as a function of reward magnitude. In addition, the effect of reward on somatosensory responses was mediated by the dopaminergic system, as evidenced via pharmacological manipulations (Pleger et al., 2009). As observed in our own study, the contribution of motivational signals to sensory processing extends to other sensory systems, with modulatory signals detected at the level of the primary visual cortex (V1) in both rats (Shuler and Bear, 2006) and humans (Serences, 2008). Thus, it appears that motivation not only modulates sensory processing, but that such influences are present at the first stages of cortical processing. Naturally, such effects likely reflect “late” contributions from other processing stages (see next section).