The auditory and visual perception systems have developed special processing strategies for ecologically valid motion stimuli, utilizing some of the statistical properties of the real world. A well-known example is the perception of biological motion, for example, the perception of a human walker. The aim of the current study was to identify the cortical network involved in the integration of auditory and visual biological motion signals. We first determined the cortical regions of auditory and visual coactivation (Experiment 1); a conjunction analysis based on unimodal brain activations identified four regions: middle temporal area, inferior parietal lobule, ventral premotor cortex, and cerebellum. The brain activations arising from bimodal motion stimuli (Experiment 2) were then analyzed within these regions of coactivation. Auditory footsteps were presented concurrently with either an intact visual point-light walker (biological motion) or a scrambled point-light walker; auditory and visual motion in depth (walking direction) could either be congruent or incongruent. Our main finding is that motion incongruency (across modalities) increases the activity in the ventral premotor cortex, but only if the visual point-light walker is intact. Our results extend our current knowledge by providing new evidence consistent with the idea that the premotor area assimilates information across the auditory and visual modalities by comparing the incoming sensory input with an internal representation.

During language comprehension, readers or listeners routinely infer information that has not been stated literally in a given text or utterance in order to construct a coherent mental representation (situation model). We used a verification task in a behavioral study and in an event-related functional magnetic resonance imaging (fMRI) experiment to investigate the inference construction process. After having read sentences that mention the outcome of an event explicitly, implicitly, or not at all, participants verified the plausibility of short statements with respect to the context of the just read sentence. The results of the behavioral study established the verification task as a valid method for studying inferences. In the fMRI study, the dorsomedial prefrontal cortex was the most prominent area that was involved in the processing of inference statements. Regions in the left and right temporal lobes were associated with comparison processes that are based on the propositional representations of context sentence and test statements. The results are discussed with respect to levels of representations and the memory systems that underlie the verification process in the different sentence conditions.