Project01
Recovery from brain & spinal cord injury
Project02
Neural mechanism of blindsight
Project03
Neural mechanism of flexible decision making
Project04
Eye movement and attention systems in common marmosets
Project05
Structure and function of the superior colliculus
Project06
Development of selective circuit manipulation techniques
Project07
Other projects -1-
Project08
Other projects -2-
Project 01
Using a macaque monkey model with lesion of the corticospinal tract is transected at the cervical cord, we are studying the neural mechanism of large-scaled neural network reorganization for recovery of dexterous hand movements which spans not only the spinal cord, but also bilateral motor cortices and even the meso-limbic structures such as the nucleus accumbens.
Project 02
Some patients with damage to the primary visual cortex (V1) were shown the ability to perform goal directed movements such as reaching and saccadic eye movements toward the objects presented in the blind field, called “blindsight. We apply multiple techniques to the macaque monkeys with unilateral lesion of .V1 to clarify the neural circuits for the blindsight and how much of the cognitive functions such as short term memory, decision making, attention and visual awareness are retained in blindsight condition.
Project 03
Our life is sustained by the ability of flexible decision making depending on the environment. Using “the hidden target search task with changing goals”, we are studying the neural basis of explorative and exploitive decision making, and using the “risk choice task”, we are studying the neural basis of decision making between high risk-high return versus low risk-low return conditions.
Ryo Sasaki, Yasumi Ohta, Hirotaka Onoe, Reona Yamaguchi, Takeshi Miyamoto, Takashi Tokuda, Yuki Tamaki, Kaoru Isa, Jun Takahashi, Kenta Kobayashi, Jun Ohta, Tadashi Isa (2023) Balancing Risk-Return Decisions by Manipulating the Mesofrontal Circuits in Primates. Science in press
Project 04
Common marmoset are considered as a new nonhuman primate model for life science studies in which techniques to generate genetically modified animals were developed. We take advantage of marmosets having a small and liscencephalic brain (having no sulci), and are studying the neural systems controlling eye movements and visual attention. The results are expected to contribute to establishing the novel biomarkers of the neuropsychatric disorders.
Project 05
The midbrain superior colliculus is a phylogenetically ancient brain structure, which is homologous to the optic tectum in fish, amphibians, reptiles and birds, and is involved in the processing of innate sensory and motor functions in vertebrates. Its superficial layer receives primarily visual inputs and its deeper layers receive non-visual sensory inputs and projects descending motor commands to the brainstem and spinal cord. We have been studying the structure and functions of its local circuits and functions of the input and output systems by integrating the multiple methods spanning from electrophysiology in acute in vivo slice preparations, in either awake or anesthetized preparations, circuit manipulation with optogenetic and chemogenetic techniques, 2-photon laser scanning microscopes and large-scaled network simulations.
Project 06
Recent development of circuit manipulation techniques with optogenetics or chemogenetics enabled us to demonstrate the functions of particular circuits selectively and causally by using genetically modified animals and viral vectors in model animals as represented by rodents. However, these cutting-edge techniques are not still fully available in nonhuman primates. To further advance our understanding of higher cognitive functions, it is critical to make these techniques fully available in nonhuman primates. We combined viral vectors and succeeded in manipulating a particular neural pathway in the spinal cord of macaque monkeys and affected the behavior for the first time in the world (Kinoshita et al. Nature 2012). We are further developing these techniques to be useful in a variety of neural circuits of the primate brain.
Project 07
(1) Species differences in the structure of sensori-motor systems
We have been studying the connectivity and gene expression of sensori-motor systems, especially the pyramidal systems in different animal species in health and disease.
Project 08
(2) Information processing in the sensorimotor systems revealed by decoding methods
We have been studying how the information is processed among the sensory and motor systems in macaque monkeys using multi-channel recording and decoding techniques.
