[Neural and molecular mechanisms of visual memory and imagery in the primate]

In this talk, I examined the cortical mechanisms involved in the memory formation and activation for visual images. Our ability to "see with the mind's eye" has been of interest to philosophers and scientists for a long time. Today we have a variety of approaches (including neuroimaging, electrophysiological, psychophysical and neuropsychological methods) to investigate where and how the images of objects, scenes and living beings are generated, stored and maintained in the brain. The aim of my study is to provide the solid neurophysiological basis for these studies. I first devised an animal model of imagery task: Macaque monkeys were trained to memorize visual objects in associative memory and to retrieve the image of an object from long-term storage according to an associative cue. I addressed the following basic questions, and described the answers we obtained: (1) Where in the brain is the mnemonic representation of visual images stored and how is it organized? (2) How is the representation created and what is the molecular basis of neural circuit reorganization? (3) Which neural circuits enable the reactivation of the image representation and the memory retrieval? (See for further details. http://www.physiol.m.u-tokyo.ac.jp/).