It has been suggested that the higher brain functions in primates including humans are regulated by the highly developed cerebral cortex. A large number of research studies using primates particularly macaque monkeys have been actively carried out to clarify the functions of each area and anatomical connections between areas. In contrast, the underlying circuit mechanisms of higher functions remain elusive, because of the difficulties in generating genetically modified macaque monkeys. A transgenic technology based on virus vector infection has been developed recently in order to overcome these problems, and the approaches for primates have been proposed.
We have thus far clarified functional differences among areas in the visual association cortex and prefrontal cortex of macaque monkeys by combining lesion studies with electrophysiology recordings; we have led the world in research on functions of the cerebral association cortex (e.g., Fujita et al., Nature, 1992; Tanaka, Science, 1993; Wang et al., Science, 1996; Matsumoto and Tanaka, Science, 2003; Mansouri et al., Science, 2007; Buckley et al., Science 2009). On the basis of such research, it has been considered that a specific function is rarely generated by information processing in one site of the brain, and is mainly regulated by functional interaction across multiple sites. Although methods of selectively manipulating the interaction between brain sites are necessary for further advancement of research, available methods are very limited. We are developing a method of blocking the projection of a specific site to another specific site by double-virus infection to study the interaction between areas in the visual association cortex, prefrontal cortex, and the two cortices.
