Messages from Haruo Kasai


Synapses, especially spine synapses, are rich in hundreds of crucial molecules that play a role in intelligence and mental health disorders. More and more, we're understanding that these molecules do more than just contribute to basic learning processes like Hebbian learning. Our research has revealed additional learning rules, encompassing intrinsic dynamics (important for regularization, etc.) and mechanics (critical for the integration of neural circuits). In the cerebral cortex, learning and cognition are not merely parallel processes; they are deeply interconnected within the same neural structures. This points to a more profound role of synapses in the comprehensive cognitive functions that engage the entire brain. Traditionally, the study of cognitive functions and synaptic behavior has been conducted in separate research silos. However, our latest research shows that precise manipulation of synaptic functions, using specially designed probes, can profoundly alter cognitive processes. This advancement suggests a nearing convergence of these two fields of study. We are eagerly seeking collaborative partners to delve deeper into the complex world of synaptic mechanics and probe design. We welcome applications from doctoral researchers and graduate students who are enthusiastic about breaking new ground in this area.                                                              (2024.02.02)


One year has passed since our groundbreaking discovery of mechanical synaptic transmission at the spine synapse, where actin fibers are concentrated. Our investigation into this phenomenon has led us to establish several new approaches using cutting-edge technologies, which have shed light on key questions about the fundamental nature of memory and learning.

The mechanical transmission of information from postsynaptic learning to presynaptic terminals is a crucial aspect of cognitive function, not only for memory but also for the unification of various input modalities into a single, integrated experience. While artificial intelligence (AI) has made remarkable strides in recent years, it is important to note that there is a fundamental difference between the way AI and the human mind process information. AI relies solely on electrical signals for information transfer, whereas the human brain utilizes complex mechanical mechanisms in synapses to encode memory.

Our mind is unique in its ability to self-unify and integrate environmental input as a whole. Unlike AI, which assigns information to specific modalities, the coding of the brain does not disclose the mode of input. Instead, the diversity of neuronal structure allows for the display of numerous modes of input, such as vision, sound, and pain.

At our laboratory, we are dedicated to studying cognitive function at both the molecular and cellular levels. We welcome new collaborators from around the world to join us in this exciting research. Please feel free to contact us via email to learn more about our work and how you can get involved.


We have reported fascinating new properties of bran spine synapses in the end of the last year (Nature 600:686, 2021.11). We found the dendritic spine enlarges with a strength of muscle tension, and pushes the presynaptic terminal to promote exocytosis (PREST). This likely is a cellular basis of short-term and working-like memories, because PREST occurs rapidly, synapse specific, and lasting up to 20 min. We are now characterizing their molecular and cellular features so that we are able to identify the cognitive roles of PREST in various brain areas. Also, theoretical investigation of the role of rapid spine dynamics has been started in International Institute for Neurointelligence. Thus, we are studying both  molecular and cognitive functions, and welcome new collaborators to join in our laboratory from all over the world. Feel free to contact us via e-mail.



We have found the presynaptic actions of spine enlargement of spines whose proof  was technically demanding. Spine enlargement is destined to push the presynaptic terminals, but its proof has been extremely difficult. Using various recent technology, we have clarified the pushing effects are potent. It took 16 years after our discovery of spine enlargement. Fortunately we found unexpected features in the pushing, and it appears to me that he pushing effect is the most important discovery after mEPP (Fatt & Katz 1950). How its underlie the cognitive function?  

We are improving the synaptic memory probes to elucidate spacio-temporal distributions of memory synapses.

Another niche is monoamine functions in the Nucleus accumbens (the ventral striatum) and PFC in emotional behaviors, lead by Sho Yaghishita. 

We use new optogenetics, two-photon microscope, uncaging, electrophysiology, molecular biology, behavioral tasks to uncover the most mysterious aspect of brain functions, such as perception, learning & memory, emotion, and mental disorders (depression, schizophrenia, autism spectrum disorders). In achieving these, we have been based on the most prominent types of synapse, spine synapses, and we are heading for delineating the entire functional circuits underlying the brain functions and disorders. We welcome collaborators from abroad at various levels, master course and PhD students, post doctoral fellow and visiting professorships. If you are interested, do not hesitate to contact us with e-mail.                (2020.04.22)