Development of Brain Maps and Their Disorders
The cerebellum of fish, unlike that of humans, appears uniform without
visible folds or boundaries. However, the neural circuits in the fish cerebellum
are quite similar to those in humans, with only minor differences. We have
elucidated the efferent pathways of the zebrafish cerebellum using various
methods. By employing calcium imaging, we visualized neural activity specific
to swimming and nystagmus, demonstrating that the anatomical maps correspond
to maps of neural activity. Using optogenetics to intervene in neural activity
in these areas resulted in corresponding behavioral abnormalities. These
findings were published in PNAS in 2014, accompanied by editorial comments
from Dr. Hitoshi Okamoto of RIKEN (Matsuiet al., Proc. Natl. Acad. Sci. USA, 2014).
Through these efforts, we successfully mapped the functional areas of the
vestibulocerebellum and spinocerebellum in fish. However, there are still
unknown regions. In humans, the functional analysis of the vestibulocerebellum
and spinocerebellum has progressed, but the role of the cerebellum in higher
functions such as social behavior remains largely unexplored. We are currently
investigating the cerebellum of fish and humans, particularly the parts
involved with the cerebrum, to understand their potential deep connections
with various developmental disorders. We also aims to provide deeper insights
into autism and ADHD.