Synchronization between temporal and parietal cortex during multimodal object processing in man

A series of recordings in cat visual cortex suggest that synchronous activi ty in neuronal cell ensembles serves to bind the different perceptual quali ties belonging to one object. We provide evidence that similar mechanisms s eem also to he observable in human subjects for the representation of supra modal entities. Electroencephalogram (EEG) was recorded from 19 scalp elect rodes (10/20 system) in 19 human subjects and EEG amplitude and coherence w ere determined during presentation of objects such as house, tree, ball. Ob jects were presented in three different ways: in a pictorial presentation, as spoken words and as written words. In order to find correlates of modali ty-independent processing, we searched for patterns of activation common to all three modalities of presentation. The common pattern turned out to be an increase of coherence between temporal and parietal electrodes in the 13 -18 Hz beta1 frequency range. This is evidence that population activity of temporal cortex and parietal cortex shows enhanced coherence during present ation of semantic entities. Coherent activity in this low-frequency range m ight play a role for binding of multimodal ensembles.