Introduction: Novelty processing is one of the basic survival
mechanisms for living organisms. Among the various types of novelty,
stimulus novelty is the effect created by stimuli that are unlikely to be
encountered throughout one’s lifetime. However, the oddball design
mostly used in studying stimulus novelty also includes an obligatory
contextual novelty effect, which actually requires the presence of
schemas about sensory input in the memory. In this study, we aimed to
investigate the neural circuits related purely to the detection of stimulus
novelty using functional magnetic resonance imaging (fMRI) by applying
an experimental design that excludes any contextual novelty effect.
Methods: Fifteen right-handed healthy participants were included in the
study. The stimulus novelty effect was generated by the images of objectlike
structures that could not be named and did not correspond to a
real object. These stimuli were shuffled with images of familiar objects
frequently encountered in daily life. SPM12 and CONN were used for
the preprocessing stages and activation analysis of fMRI data. In the
analyses, the cluster formation threshold was determined as p <0.001
and the cluster level significance threshold with family-wise error (FWE)
correction was set at pFWE <0.05.
Results: The activity of the fusiform, middle occipital, inferior occipital
and superior occipital gyri increased during the processing of the
stimulus novelty, while the activity of the inferior parietal cortex and
supramarginal gyrus decreased.
Conclusion: With the experimental paradigm that excluded the
confounding effects of contextual novelty, anatomical regions that
respond specifically to stimulus novelty could be identified. Our results
suggest that, while stimulus novelty intensively activates brain areas
related with higher-order visual processing, the brain regions that
associate sensory inputs with the schemas in the memory are less active.
Keywords: Functional magnetic resonance imaging, novelty processing,
stimulus novelty, visual processing