Article Figures & Data
Figures
- Figure 1.
Experimental paradigm. A, Visual stimuli with two attributes: degree of reality, i.e., monkey (Mon) or cartoon (Car), and reward size, i.e., large or small. B, Visually guided saccade task under different reality and reward contexts. After fixation on Fixation Point 1 (Fix1) for 500 ms, one of eight visual stimuli (A) was briefly presented (S1), followed by a delay (1,000 or 500 ms) and the presentation of Fixation Point 2 (Fix2). After fixation on Fix2, we presented a visual stimulus (S2), which was the same as S1 except for the gaze direction (Fig. S1), followed by a target. The animal was required to make a visually guided saccade toward the target to receive a large or small reward, as indicated by S1 and S2 (M1L, M2L, C1L, and C2L for a large reward; M3S, M4S, C3S, and C4S for a small reward).
- Figure 2.
A, Persistent focus of attention toward eye region of the monkey face stimuli. Heat maps of each animal's gaze during the early and late half of the 500 ms S1 presentation period are shown for the four types of visual stimuli: Monkey_Large, Monkey_Small, Cartoon_Large, and Cartoon_Small. B, Left, Temporal change in gaze position during the S1 presentation period. We analyzed gaze position for three areas, “Eyes,” “Face without eyes,” and “Outside of face.” The ratio of time spent in each area was calculated every 50 ms. Top right, Time spent looking around the eyes during the last 50 ms of S1. Bottom right, Regression coefficient βs of reality on the x-axis, and regression coefficient βs of reward on the y-axis, for duration of gaze toward eye region of the S1 (see Materials and Methods). C, SRT distributions. Top, Saccades after the presentation of monkey and cartoon faces. Bottom, Saccades after the presentation of faces associated with a large and small reward. Reaction times are z-normalized according to the mean and standard deviation of the reaction times for leftward and rightward saccades (see Materials and Methods). D, Preferences for monkey and large-reward–associated faces. Preferences were determined via a two-alternative forced–choice procedure as part of the stimulus-assessment task (Fig. S2). The chosen face in the assessment task was used as the stimulus in the following visually guided saccade procedure. Values on the x-axis denote the preference of each stimulus, such that “1:0” denotes a complete preference for the stimulus and “0.5:0.5” denotes equal preference for the stimuli. Box plots indicate median and 25th–75th percentiles.
- Figure 3.
The ratio of neurons with significantly larger excitatory or inhibitory responses during each task period, compared with the baseline activity measured 500 ms before Fix1.
- Figure 4.
Examples of excitatory single-neuron responses to the S1 and S2 showing reality, reward, or congruency information in different amygdala nuclei. We compared the neuronal activity elicited by the monkey versus cartoon face stimuli (reality effect, left column), the face stimuli associated with the large versus small reward (reward effect, middle column), or the congruent versus incongruent gazes with the future target positions (congruency effect, right column). A, Lateral nucleus. B, Basal nucleus. C, Central nucleus. The yellow area in each diagram indicates the periods considered in the analyses. The black dots inside the raster plots denote the time points at which the neuronal activity is significantly different between the stimuli.
- Figure 5.
The regression coefficient βs of “reality” and “reward” effects for neuronal responses to the S1 (left column) and S2 (right column) of neurons that showed significant excitatory responses during S1 and/or S2 periods (see Materials and Methods, 59 lateral, 60 basal, and 54 central neurons). Neurons with a significant effect for reality only or reward size only (p < 0.05, two-way ANOVA) are shown as red squares and blue circles, respectively. Neurons with a significant effect for both reality and reward size are shown as green triangles. Red and blue lines on the histograms denote the mean reality β and the mean reward β, respectively. A, Lateral nucleus. B, Basal nucleus. C, Central nucleus. S1, stimulus 1; S2, stimulus 2. Asterisks denote that the mean coefficients are significantly higher than 0 (*p < 0.05; **p < 0.01; Wilcoxon signed-rank test).
- Figure 6.
A, Segregated distribution of neurons that significantly discriminated the degree of reality and/or reward size (p < 0.05, two-way ANOVA) in the amygdala subnuclei. The number of neurons affected by the reality factor, reward factor, both, or neither is visualized as Venn diagram. B, The number of neurons showing the reality effect (M > C indicates a significantly stronger response to monkey versus cartoon faces) and reward effect (L > S indicates a significantly stronger response to faces associated with a large vs small reward). The ratios of the numbers of neurons, relative to the neurons modulated by either the reality or reward factors, are color-scaled.
- Figure 7.
A, Time course of reality- and reward-based signals in neuron populations showing excitatory responses to the S1 and S2 in the lateral, basal, and central nuclei. The AUC values of the ROC analysis enabled us to compare responses to monkey versus cartoon faces (monkey vs cartoon, magenta) or large versus small rewards (large vs small, cyan). A value over 0.5 denotes the degree of discrimination between monkey and cartoon faces or between large and small rewards. The magenta and cyan dots in the top part of the graphs denote the time points at which the AUC values for reality and reward, respectively, are significantly different from 0.5. B, Consistent reality (left column, M > C indicates a significantly stronger response to monkey vs cartoon faces) and reward (right column, L > S indicates a significantly stronger response to faces associated with a large vs small reward) information across the S1 and S2 periods. We plotted the coefficients of reality and reward of each neuron during the S2 period against those coefficients during the S1 period. Neurons with a significant reality or reward effect in S1 only, S2 only, or both (p < 0.05, two-way ANOVA) are shown by squares, circles, and triangles, respectively. The inserted histograms show the distributions of the coefficient markers across the diagonal dashed lines.
- Figure 8.
Distribution of Spearman's rank correlation coefficients between the mean neuronal responses to each stimulus during the S2 and the mean SRTs after each stimulus. The top row is for neurons showing reality effect, and the bottom row is for neurons showing reward effect. Black lines on the histograms denote 0 of the correlation coefficients, respectively.
- Figure 9.
A, The population neurons that discriminated the degree of reality only, reward size only, and both (p < 0.05, two-way ANOVA) showed characteristic temporal dynamics. The activity of each neuron is presented as a row of pixels above the histograms. The yellow area in each diagram indicates the periods used in the analyses in B. B, Mean normalized neuronal activity in the latter half of the Fix1 and Fix2 periods. Asterisks denote significant differences (*p < 0.05; **p < 0.01; one-way ANOVA with post hoc Tukey’s test). Error bars, 1 standard error. Real, reality; Rwd, reward.
- Figure 10.
A, Estimated locations of the recorded neurons in two monkeys, plotted onto serial coronal sections of MRI images obtained with the recording chamber and the grid system in this example, 2 mm apart, filled with gadolinium. The data are displayed in an anteroposterior order, from 1 mm posterior to 2 mm anterior for Animal P and from 1 mm posterior to 1.5 mm anterior for Animal C to the anterior commissure (AC), respectively. Excitatory-responsive neurons with a significant effect of reality only, reward only, or both (p < 0.05, two-way ANOVA) and nonsignificant effects of both reality and reward are shown by red squares, blue circles, green triangles, and black crosses, respectively. Inhibitory-responsive neurons are shown by small dots. La, lateral nucleus; Ba, basal nucleus; Ce, central nucleus. B, Mediolateral and dorsoventral distribution of neurons with different effects. The data from all the coronal sections of both monkeys are included. The x-axis indicates the distance from the edge of the lateral nucleus at the AC −1 section. The y-axis indicates the depth from the top of the amygdala at the AC −1 section.
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