The face inversion effect has been used as a basis for claims about the specialization of face-related perceptual and neural processes. One of these claims is that the fusiform face area (FFA) is the site of face-specific feature-based and/or configural/holistic processes that are responsible for producing the face inversion effect. However, the studies on which these claims were based almost exclusively used stimulus manipulations of whole faces. Here, we tested inversion effects using single, discrete features and combinations of multiple discrete features, in addition to whole faces, using both behavioral and fMRI measurements. In agreement with previous studies, we found behavioral inversion effects with whole faces and no inversion effects with a single eye stimulus or the two eyes in combination. However, we also found behavioral inversion effects with feature combination stimuli that included features in the top and bottom halves (eyes-mouth and eyes-nose-mouth). Activation in the FFA showed an inversion effect for the whole-face stimulus only, which did not match the behavioral pattern. Instead, a pattern of activation consistent with the behavior was found in the bilateral inferior frontal gyrus, which is a component of the extended face-preferring network. The results appear inconsistent with claims that the FFA is the site of face-specific feature-based and/or configural/holistic processes that are responsible for producing the face inversion effect. They are more consistent with claims that the FFA shows a stimulus preference for whole upright faces.

We investigated the neural substrates involved in visuo-haptic neuronal convergence using an additive-factors design in combination with fMRI. Stimuli were explored under three sensory modality conditions: viewing the object through a mirror without touching (V), touching the object with eyes closed (H), or simultaneously viewing and touching the object (VH). This modality factor was crossed with a task difficulty factor, which had two levels. On the basis of an idea similar to the principle of inverse effectiveness, we predicted that increasing difficulty would increase the relative level of multisensory gain in brain regions where visual and haptic sensory inputs converged. An ROI analysis focused on the lateral occipital tactile–visual area found evidence of inverse effectiveness in the left lateral occipital tactile–visual area, but not in the right. A whole-brain analysis also found evidence for the same pattern in the anterior aspect of the intraparietal sulcus, the premotor cortex, and the posterior insula, all in the left hemisphere. In conclusion, this study is the first to demonstrate visuo-haptic neuronal convergence based on an inversely effective pattern of brain activation.

Everyday experience affords us many opportunities to learn about objects through multiple senses using physical interaction. Previous work has shown that active motor learning of unisensory items enhances memory and leads to the involvement of motor systems during subsequent perception. However, the impact of active motor learning on subsequent perception and recognition of associations among multiple senses has not been investigated. Twenty participants were included in an fMRI study that explored the impact of active motor learning on subsequent processing of unisensory and multisensory stimuli. Participants were exposed to visuo-motor associations between novel objects and novel sounds either through self-generated actions on the objects or by observing an experimenter produce the actions. Immediately after exposure, accuracy, RT, and BOLD fMRI measures were collected with unisensory and multisensory stimuli in associative perception and recognition tasks. Response times during audiovisual associative and unisensory recognition were enhanced by active learning, as was accuracy during audiovisual associative recognition. The difference in motor cortex activation between old and new associations was greater for the active than the passive group. Furthermore, functional connectivity between visual and motor cortices was stronger after active learning than passive learning. Active learning also led to greater activation of the fusiform gyrus during subsequent unisensory visual perception. Finally, brain regions implicated in audiovisual integration (e.g., STS) showed greater multisensory gain after active learning than after passive learning. Overall, the results show that active motor learning modulates the processing of multisensory associations.

Recent fMRI studies have found that distinct neural systems may mediate perceptual category learning under implicit and explicit learning conditions. In these previous studies, however, different stimulus-encoding processes may have been associated with implicit versus explicit learning. The present design was aimed at decoupling the influence of these factors on the recruitment of alternate neural systems. Consistent with previous reports, following incidental learning in a dot-pattern classification task, participants showed decreased neural activity in occipital visual cortex (extrastriate region V3, BA 19) in response to novel exemplars of a studied category compared to members of a foil category, but did not show this decreased neural activity following explicit learning. Crucially, however, our results show that this pattern was primarily modulated by aspects of the stimulus-encoding instructions provided at the time of study. In particular, when participants in an implicit learning condition were encouraged to evaluate the overall shape and configuration of the stimuli during study, we failed to find the pattern of brain activity that has been taken to be a signature of implicit learning, suggesting that activity in this area does not uniquely reflect implicit memory for perceptual categories but instead may reflect aspects of processing or perceptual encoding strategies.