The processing of audiovisual information is an important aspect of object recognition since many objects are characterized by visual and auditory features. The images and sounds of everyday life objects are often associated with positive or negative emotions. There is evidence that emotional valence modulates the neural processing of object images and sounds presented in isolation. However, the impact of emotional valence on the neural processing of audiovisual objects is unknown. The aim of the present study was to investigate the influence of evaluative conditioning on cortical plasticity in human audiovisual object processing. We used functional magnetic resonance imaging (fMRI) to analyze changes in cortical audiovisual processing of unfamiliar artificial objects
and sounds in naive subjects (Pre fMRI) and after a behavioral evaluative conditioning session in which subjects acquired positive and negative emotional associations with the artificial stimuli (Post fMRI). Results from the Post fMRI showed that additional brain regions were recruited for the processing of positively and negatively conditioned stimuli compared to the Pre fMRI data. The processing of positive stimuli additionally involved the left caudate nucleus and the right medial prefrontal cortex whereas the processing of negative stimuli additionally recruited the left insula. Furthermore, a congruence effect for matching emotional stimulus pairs was found in the right transversal temporal gyrus. These results indicate that emotional valence modulates object-related audiovisual processing. Moreover, we were able to show that emotional valence can be induced by a behavioral evaluative conditioning procedure leading to plastic changes in the processing of audiovisual stimuli.

fMRI; audiovisual integration; valence; evaluative conditioning