Haruo Kasai

National Institute of Physilogical Sciences, Okazaki, Japan

The Kasai Lab was the first to accomplish diffraction limited 2-photon photolysis of caged glutamate, which was developed in our lab. Using focal uncaging from MNI-Glu, they have been able to mimic quantal release, the fundamental chemical synaptic event in the CNS. Using this approach, they have developed techniques for producing maps of receptors in living cells (see below). Our work together is supported by a R24 grant from the National Institute of General Medical Sciences (only the 3rd such grant ever awarded), and by a Program Grant from the Human Frontiers Science Program (with Martin Bootman-this grant was ranked 11th out of 634 applicants.)

2D projections of 3D images of postsynaptic dendritic volume in CA1 neurons in slices and the AMPA-R density imaged by 2-photon photolysis of MNI-Glu in that space. Lateral and axial resolution of mapping are shown right. These results were reported in Nature Neuroscience (2001), 4, 1086.

The Kasai lab have now applied this 2-photon mapping technique to image long-term potentiation at single dendritic spine heads in CA1 hippocampal neurons in brain slices. They have shown definitely that Hebb's learning principle can apply to a single synapse, ie. they combine simultaneous postsynaptic depolarization with brief photochemical tetanus (720 nm, 2 Hz for 1 min, 5 mW per uncaging event), to induce profound morphological plasticity (upper panel shows fluorescent images of eGFP-filled dendrites imaged at 910 nm). These technically challenging experiments with their dual 2-photon microscope permit receptor imaging at normal resting potentials (over a period of more than 80 mins). These results have been published in Nature (2004) 429, 761).

I visited the Kasai lab in November 2004. We spent 4 days looking at Zen temples in Kyoto (An account of my trip with many photos is here). We did some work too (honest). Here I am with Kasai and Masanori Matsuzaki (left), and with Masanori and Jun Noguchi (right).