To test whether the activity related to the hypothetical outcomes from a particular target changed with the animal’s choice (Figure S5), the following model was applied separately for each combination of chosen and unchosen targets Fulvestrant cell line in loss and tie trials for experiment I. M8i:y=bo+bhHwinFor experiment II, another regressor was included to factor out the effect of actual outcome from the chosen target. M8ii:y=bo+blossOloss+bhHwinThen, the correlation coefficient between the standardized regression coefficients (bh) estimated for two different choices was calculated for the same unchosen winning target. As a control analysis, we also calculated
the correlation coefficient between the regression coefficients associated with BKM120 the same chosen target but two different unchosen winning targets. The angular difference in the retinal positions of the unchosen targets during the feedback period was matched for these two analyses (Figure S5). Therefore, if the activity related to hypothetical outcome merely reflected the properties of visual receptive
fields, these two correlation coefficients would be similar. To test whether the neurons significantly modulating their activity according to a particular factor (e.g., AOC or HO) are anatomically segregated from the remaining neurons, MANOVA was applied to their anatomical locations with the statistical significance as the factor (Figure 3; Figure S3). For this analysis, neurons recorded in all the animals were combined separately for the DLPFC and OFC. We thank MRIP Irina Bobeica, Mark Hammond, and Patrice Kurnath for their technical assistance. This work was supported by Kavli Institute for Neuroscience at Yale University and US
National Institute of Health grants (DA029330 and EY000785). “
“Synapse formation and elimination are fundamental elements in both the initial construction of neural circuits and the experience-dependent modification of the mature nervous system (Sanes and Lichtman, 1999 and Trachtenberg et al., 2002). During development, refinement of neural connectivity after axon guidance and dendrite morphogenesis are characterized by dynamic, regulated synaptogenesis and synapse elimination (Cline, 2001 and Hua and Smith, 2004). Even in mature animals, a certain amount of “synapse turnover” is maintained, suggesting that a balanced synapse formation and elimination are likely required for the maintenance of circuit functions. It is generally believed that neuronal activity drives the modification of neural circuits through strengthening and weakening connectivity between neurons (Balice-Gordon and Lichtman, 1994 and Goda and Davis, 2003). Although a large body of work has focused on the molecular mechanisms of synapse formation, less is known about the process of synapse elimination. Very few studies have focused on the mechanisms that coordinate synaptogenesis and synapse elimination.