We also thank A. Scimemi for precious help and suggestions on STC recordings. This work was supported by grants from the Swiss National Foundation (3100A0-100850, 3100A0-120398, and NCCR Transcure) to A.V. and from the University of Lausanne, grant FBM 2006, and Novartis Foundation (26077772) to P.B. M.S. is recipient of a University of Lausanne FBM PhD fellowship. “
“A substantial part of the knowledge that we acquire in real life is a consequence of a one-time exposure to an event, yet the brain mechanisms that

underlie this type of rapid learning are largely unknown. While the prevalent example of single-event knowledge acquisition is episodic memory (Roediger et al., 2007 and Tulving, 1983), another type of real-life single-event learning is insight: the sudden realization BIBF-1120 of a solution to a problem (Hebb, 1949 and Köhler, 1925). Although insight is most often discussed in the context of cognitive tasks such as problem solving (Kaplan and Simon, 1990 and Sternberg and Davidson, 1995), abrupt improvements in performance, as well as the subjective “Aha!” experience characteristic of insight, can also be observed in perception (Porter, 1954, Rubin et al., selleck chemical 1997 and Rubin et al., 2002). The sudden realization of the solution may happen spontaneously, but it can also be induced by an external cue, both in cognitive problem solving (Maier, 1931) and in

perception. Readers may be able to experience induced perceptual insight for themselves by viewing Figure 1, which was generated by degrading a real-world picture, taking a few moments to try to identify

the underlying scene, and then turning to Figure 2 (next page), which shows the original image. Upon re-exposure to the degraded 4-Aminobutyrate aminotransferase image, or “camouflage” (Figure 1), many observers report perceiving a compelling depiction of the underlying scene—just moments after the very same image appeared as a meaningless collection of ink blots. In daily life, information that results from moments of insight is, almost by definition, incorporated into long-term memory: once we have realized a new way to solve a problem, or to perform a task better and faster, we are not likely to forget that insight easily. But what is the neural basis of this long-lasting nature of insight? Other forms of learning typically require long training periods and many repeated trials, as has been observed in sensory and perceptual learning (e.g., Gauthier and Tarr, 1997, Karni and Sagi, 1991 and Seitz and Watanabe, 2009), motor learning (e.g., Newell and Rosenbloom, 1981), and rote-learning in animals (e.g., Stevens and Savin, 1962). These timescales accord well with the long-held idea that incorporation of new knowledge into long-term memory involves synaptic modifications that require gradual processes, sometimes over weeks or months (Dudai, 2004, Hebb, 1949, Martin et al., 2000 and Squire and Kandel, 1999).