What we seem to know about meaning in the brain
In this talk I will present some recent psychophysical and electrophysiological experiments on semantic processing from our laboratory. First, using visual motion adaptation and motion after-effects, I will provide evidence that semantic representations of motion VPs do not rely on sensory codes for directional movement, arguing against embodied views of meaning. Second, applying advanced data analysis methods from non-linear dynamical systems theory to EEG time series, I will show that visual word recognition and lexico-semantic processing, separated by a semantic memory access boundary, correspond to two dynamically distinct phases of cortical processing. Third, I will describe a specific and reproducible oscillatory signature for reference shifts in temporal indexicals, and suggest that this may be a manifestation of a basic semantic binding operation carried out by the cortex. Taken together, these findings return a view of meaning in the b
rain that appears to be not so distant from that of the formal/computational semanticist, thereby inviting the application of logical tools to the design and interpretation of neuroscience experiments.