Outline of Research
"Elucidating general principle (common among genetic, neural and cognitive) that allows biological evolution and cultural creativity to happen." has been the goal of our research over past years. Our previous studies suggest some conceptual clues toward this goal including: (1) the polysemic (multiple meanings) and (2) inclusive nature of (genetic, neural and cognitive) dynamic information encodings; and (3) a phase transition caused through such dynamics in the respective system. The neuroscientific mechanism behind primates' intellectual evolution has been proposed as "triadic niche-construction" which is comprised of three classes of "niches" that are gradually expanding through dynamic, mutual interactions among them. Specifically, these are: (1) learning-induced brain expansion (neural niche), perhaps subserved by neurobiological mechanisms including neurogenesis and thereby induced modifications of neural circuits; (2) phase transition-like changes of brain functions that lead hominid brains to express human-specific cognitive capacities (the cognitive niche) subserved by those expanded brain areas; and (3) modification of environments (the ecological niche) made possible by expanded capabilities, which feed back on the brains to further expand the neural niche. The precursors for such triadic niche interactions can be found in non-human primate brains.
We identified modes of human-specific cognitive capacities, and the brain areas responsible for those capabilities. Next, the dynamics of the neural coding was detected through changes induced in trained macaque monkey brains. Finally the neurobiological mechanisms subserving such changes were studied in marmosets. Through these genetic-neural-cognitive integrative experimental paradigms, of which respective representative results are depicted below, we have been working to elucidate general neurobiological principles driving the evolution of human cognitive functions and resulting creativity.
1. Human Cognitive Neuroscience
The ability to accept ideas provisionally for reasoning and concept formation allows human thoughts to handle ambiguous, abstract, and symbolic events. Such information processing is likely handled by the higher association cortices, detached from the immediate physical environment. The nature of such human-associated cognition has been studied psychophysically, and by fMRI, to comprise a foundation for empirical investigations using primate models.
2. Macaque Neurophysiology
Neural coding in higher association cortices, compared to primary cortices, is less constrained by the physical laws of the environment. It tends to be more abstract, less contextual, and less history dependent; thus it may be characterized by a polysemic nature. As a result, conventional naive statistical analyzes are not sufficient -- nor appropriate -- for describing and understanding its coding principles. We propose that understanding the neurophysiology of higher cortices necessitates a more inclusive view. We have studied such modes of neural codings in three representative association areas under natural behavioral conditions (including social interactions).
3. Marmoset Neurobiology and Behavior
We studied the biological bases in marmosets of the changes in neural response properties and expansion by acquisition of higher cognitive functions (including tool-use) that were detected earlier in macaques. We also established a series of behavioral test batteries for studying the neural bases of human-associated traits in non-human primates in order to determine their origins through convergent evolution or shared precursors.
We shall extrapolate, reorganization, and unify our previous results to further elucidate common principles of the "triadic niche-construction" through two novel flagship projects:
1. Mind-brain-body interaction (human and non-human primate-specific brain-body links)
This will be the conceptual piece of the laboratory project, mostly using human subjects and macaque monkeys, but partly linking with marmoset neurobiology. Previous results indicate that human-associated cognition is subserved by expanded brains derived from thre unique body structure resulting from bipedalism. This, in turn, extended the capacity of primates to interact with their physical environments, including tool-use. This suggests a potential primate-specific mechanisms that directly interacts with internal organs in addition to somatovisceral and/or autonomic mechanism. This may include those controlling the immune system, endocrine system, and others. Also, this mechanism can potentially demonstrate how the problems of the mind (such as socially induced psychological stress) can alter one's physical state -- a puzzle that has been merely phenomenologically speculated without empirical evidence. We shall target this problem, by combining human TMS and fMRI together with psychophysical studies, macaque neurophysiology and neuroanatomy, and marmoset molecular genetics.
2. Autonomous cog-bio analyzer (long-term neuro-behavioral changes of cognitive functions)
This will be a technical piece of the flagship laboratory project, utilizing our recently patent-applied apparatus [特願2013-118178 (domestic)] & [#PCT/JP2013/006954 (international)] to integrate various disciplines and technologies, using mostly marmosets. This project includes (1) behavioral analyzes, (2) multiple neuronal wireless recording-stimulation technologies, (3) theories of complexity science, (4) novel data fusion and methods, (6) molecular genetics, (7) brain imaging, (8) psychiatric disorders, and other components. This hypothesis-free analyzer can spontaneously detect testable hypotheses, and thereby autonomously optimize (by adjusting parameters of each component) the whole system to demonstrate such hypotheses. It can be used to autonomously validate any variety of long-term neuronal manipulation (such as drug delivery, genetic manipulation, developmental behavioral alterations, stimulation, lesions, etc.). We expect the completed system to constitute a major breakthrough in the way neuroscientific studies of primate higher cognitive functions are conducted.