Grant: Foundation Grant

<html> <body> <p>The vast lateral temporal region that lies below the auditory superior temporal gyrus and extends posteriorly into the inferior parietal lobule has expanded enormously in the human brain relative to that of other primates. This huge multisensory region has been implicated in the ability to infer the intentions of others and the enormously expanded ability to cooperate and communicate, perhaps largely based on the emergence of complex semantic categories in the human brain. Fronto-temporal interactions are often considered to subserve the high-level retrieval of specific category information. In the monkey, many areas with distinct cytoarchitectonic signatures have been identified in this multisensory region and distinct fronto-temporal circuits have been described in great detail. By contrast, in the human brain only a gross subdivision has been made. It is therefore surprising that, in the human brain, no effort has been made to establish the <i><u>cytoarchitectonic</u></i> homologues of these multisensory monkey areas and to examine similarities and differences between the two species. It is a major obstacle in research on the highest forms of cognition that these multisensory cytoarchitectonic areas <i>have not been identified in the human lateral temporal lobe and their extension into the inferior parietal lobule</i>. This program grant aims to change this unsatisfactory state: We shall carry out an exhaustive comparative examination of the cytoarchitecture and myeloarchitecture of the lateral and ventral parts of the temporal lobe, including the points of transition into the areas of the inferior parietal lobule in the macaque monkey, chimpanzee, and human brains in order to establish the various areas with common criteria and identify similarities and differences. Furthermore, we shall examine the connectional patterns of the to-be-identified areas in the human brain by using resting state connectivity and diffusion MRI methods to test specific predictions from the known and precisely established connections of these areas in the macaque monkey. The aim of this research is not only to provide modern and detailed cytoarchitectonic and connectional maps of the multisensory areas in this most complex part of the human brain, but primarily to provide the anatomical basis to explore in detail functional interactions between specific frontal and temporal modules. To do so the areas and the anatomical fronto-temporal and temporo-parietal sub-circuits must be established. We say sub-circuits because the focus of interest is not on global fronto-temporal functional interactions, but rather specific interactions that might underlie several related but distinct functional processes giving rise to the highest forms of cognition. The sub-circuits to be identified in the human brain will be explored with functional neuroimaging in the human, accompanied by comparable studies in the monkey brain. The similarity/differences (overlap/non-overlap) in the dynamic changes in the coupling involving particular fronto-temporal sub-circuits in the left (language-dominant) and right hemispheres of the human brain, as well as the comparison with findings of comparable dynamic coupling studies in the nonverbal monkey, will provide important insights on functional differentiation in this vast region and important insights into what makes the human brain special.</p> </body> </html>