演題番号 : S1-2-1-1
入來 篤史 / Atsushi Iriki:1
1:理化学研究所 BSI 象徴概念発達研究チーム / Lab. for Symbolic Cognitive Development, RIKEN BSI
The primate posterior parietal cortex (PPC) processes information related to environmental physical space. The human PPC has apparently expanded not only in size but also in its functional range to encompass certain abstract and higher-order conceptual spaces. Review of various forms of non-spatial representation in the PPC revealed that various kinds of non-spatial cognition can be grouped and ordered based on the levels of abstraction of the 'objects' and ideally defined spatial relations represented. Assumed coordinate systems for such 'spaces' vary depending on the abstraction level. These pseudo-spatial nature of the high-order cognition supported by the PPC may derive from the essential characteristics of the objects represented but alternatively may derive from the nature of the PPC's pre-existing information-processing mechanisms, namely as a hub for multisensory integration and representing physical environmental space. The meta-analysis illustrates that the PPC areas responsible for these novel forms of cognition are not necessarily clearly segregated, either in monkeys or humans, but does suggest a trend of gradual expansion toward the IPL as the level of abstraction proceeds. Thus, it seems that the PPC gradually incorporated high-order cognition as it expanded during hominid evolution while preserving its original principles of operation.