Abstract
What determines the preference we have for some scenes over others? Vessel & Biederman (2003) hypothesized that such preferences were mediated by a gradient of mu-opioid receptors (ligand termed “endomorphin”) in the macaque ventral cortical visual pathway. These receptors are sparse in the earliest stages, e.g., V1 and V2, but dense in the later stages (e.g., parahippocampal gyrus, pHg), where perceptual information activates the products of past experience. Experiences would be preferred that maximize the rate of endomorphin release. Such inputs will tend to be those that are richly interpretable (not just complex) insofar as they would produce high activation of associative connections in areas that have the greatest density of mu-opioid receptors. PHG was defined as a region where BOLD responses evoked when viewing images depicting places were larger than those evoked when viewing images of objects (Epstein & Kanwisher, 1998). The lateral occipital complex (LOC), a critical area for object recognition, was defined as a region where objects were larger than their scrambled versions. Preference ratings were obtained by button press for each scene while subjects were in the magnet. Scenes rated as highly preferred (above the subject's median rating) were associated with a greater hemodynamic response in the PHG compared to less preferred scenes. There was no difference in LOC as a function of preference, indicating that the larger hemodynamic response in the PHG was not a feed forward effect from LOC.