Fig. 1

Methods of measurements of the average thickness of PSD (a, b) and the index value of curvature of PSD (c, d). Sample on left was treated with control media, and sample on right was treated with 50 μM of NMDA for 5 min. (a, b) –The area of the PSD was demarcated by the postsynaptic membrane and the border of the visible dark materials that were distinct from the rest of the cytoplasm. The area enclosed by these outlines was then divided by the length of the postsynaptic membrane to yield the “average thickness of the PSD”. (c, d) –The index for the curvature of the PSD was calculated by first drawing a line between the two ends of the postsynaptic membrane (the horizontal line indicated by x), and then a second line (the vertical line indicated by y) from the highest point of the arch of the postsynaptic membrane to the first line. The value of “y” divided by “x” times 100 is the index value for the curvature of the PSD. A negative value indicates that the presynaptic terminal arches into the postsynaptic spine (c), and a positive value indicates the reverse (d). Scale bar = 0.1 μm