Outcome- and response-selective units in OFC before reward delivery. **A,** A diagram of contingencies in the instrumental odor-discrimination task. Each of four odors (Odors A, B, C and D) was associated with a distinct combination of a behavioral response (Left or Right) and an outcome (Sucrose or Water). **B,** Recording sites in OFC mapped onto the rat brain atlas (Paxinos and Watson, 1998). **C,** Proportions of outcome- and response-selective units during the intertrial interval, the odor-presentation phase, the response phase, and the reward-waiting phase. Proportions of units selective to the outcome, but not to the response (O), units selective to the response, but not to the outcome (R), and units selective to both the outcome and the response (OR) are shown. **D,** Comparisons of two selectivity indices of outcome- or response-selective units from trials with different responses or outcomes, respectively. The upper three plots show the outcome selectivity index in left trials (left sucrose trials (L-Suc) versus left water trials (L-Wat), abscissa) and that in right trials (right sucrose trials (R-Suc) versus right water trials (R-Wat), ordinate), with positive and negative values for higher activities in sucrose and water trials, respectively, than the other trial type. Green dots show individual units selective to the outcome in each behavioral phase. In the lower three graphs, the response selectivity index in sucrose trials (left sucrose trials (L-Suc) versus right sucrose trials (R-Suc), abscissa) and that in water trials (left water trials (L-Wat) versus right water trials (R-Wat), ordinate) were plotted, with positive and negative values for higher activities in left and right trials, respectively, than the other trial type. Red dots indicate individual units selective to the response in each behavioral phase. Units for which no spikes were obtained in a given comparison group were excluded. Solid and dotted lines indicate the linear fit and its 95% confidence interval. Degree-of-freedom adjusted coefficient of determination was also shown (“rsq”). The number in each quadrant is of units in the corresponding quadrant. Note that two selectivity indices of each type, response or outcome, show significant positive correlations in all behavioral phases. *** *P* < 0.001.

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