A study of rats has been published (as a letter) in Nature that reportedly shows that strengthening or weakening of synapses “is the underlying basis for memory.” The researchers are from the University of California.
Sadegh Nabavi, Rocky Fox, Christophe D. Proulx, John Y. Lin, Roger Y. Tsien and Roberto Malinow Engineering a memory with LTD and LTP. Nature. 2014.
Alford, Justine Scientists Selectively Erase And Restore Memories. IFLS. June 2, 2014. http://www.iflscience.com/brain/scientists-selectively-erase-and-restore-memories#toJ8QVs2ykmGg2mv.99