Neuroimaging studies of the higher brain functions

Abstract

Neuroimaging studies of the human higher functions by using fMRI and MEG have been carried out in the author's laboratory. Simultaneous multi-dipole estimation could depict the detailed spatio-temporal structure of brain activities (frontal, parietal, temporal and posterior parahippocampal regions) related to the auditory selective attention, with the temporal resolution of msec-order. In addition, the studies of mental rotations using 3D-fugures, alphabetical characters and hands clearly showed the spatio-temporal structure of brain activities, that is, visual-related area =>premotor area ⇔ parietal area. This neural network found in the imagery tasks corresponds with the fronto-parietal network activated associated with visually-guided hand manipulation in the real world. Moreover, we investigated the compensative neural mechanisms in the network, which would compensate for the temporal disturbances caused by delayed visual feedback. Among the related brain regions, the right inferior parietal region would be specifically related to not only the internal forward model but also the self-other differentiation mechanism. Furthermore, the neural basis of maternal love and maternal behaviors, little of which has ever been known in the human mother's brain, could be recently clarified by detailed analysis of the fMRI data. The results showed that a limited number of mother' s brain areas were specifically involved in maternal love, namely orbitofrontal cortex, periaqueductal gray, anterior insula, and lateral parts of putamen, and suggested that there would be the highly elaborate neuronal mechanism for maternal behaviors for vigilant protectiveness.