There were significant differences in response magnitudes to the five stimulus categories (F4,3327 = 26.67, P < 0.001). The face-like and eye-like patterns elicited stronger responses than the simple geometric patterns (Tukey tests, P < 0.001 and 0.01, respectively). These results indicate that the

pulvinar neurons responded well to face-related stimuli. Of these 68 visually responsive neurons, 23 neurons responded differentially VX-770 nmr to gaze direction in the frontal or profile faces of at least one of the facial models (gaze-differential), and 29 responded differentially to face orientation (face orientation-differential). Differential responses were exhibited by nine neurons to gaze direction of cartoon faces (cartoon face-differential), and

by four neurons to gaze direction of eye-like patterns (eye-like pattern-differential). Five and eight neurons responded differentially to face-like patterns (J1–4; face-like pattern-differential) and simple geometric patterns (simple geometric pattern-differential), respectively. Ratios of the gaze-differential and face orientation-differential neurons (23/68 = 33.8% and 29/68 = 42.6%, respectively) were significantly higher than those of the cartoon face-differential (9/68 = 13.2%), eye-like pattern-differential (4/68 = 5.9%), face-like pattern-differential (5/68 = 7.4%) and simple geometric BMS-777607 molecular weight pattern-differential neurons (8/68 = 11.8%; Fisher’s exact probability test, all P < 0.01). A previous study by our group demonstrated that the mean response magnitudes toward facial photos with direct gaze were significantly larger than those to facial photos with averted gaze in the monkey amygdala (Tazumi et al., 2010). We analysed the pulvinar

responses in the same manner. However, the difference in response magnitudes to these two different gaze directions was not statistically significant in the pulvinar nuclei (paired t-test, P > 0.05). Figure 6 shows the results of a cluster analysis of the 68 neurons based on the response magnitudes to the 49 stimuli during the 500-ms period after stimulus onset; although typical clusters were not observed, groups of neurons with similar response trends were identified. Units 1–34 (Cluster J) comprised neurons that responded best or second best CYTH4 to one of the face-like patterns, except for five neurons (units 15, 19, 28, 33 and 34). Units 35–39 (Cluster C/E) consisted of neurons that responded best or second best to one of the cartoon faces and eye-like patterns. Units 40–54 (Cluster W) responded best or second best to one of the facial photos of the female models, except for two neurons (units 43 and 46). Clusters Ma, Mb and Mc comprised neurons that responded best or second best to facial photos of the different male models. Cluster S consisted of neurons that responded best or second best to the simple geometric patterns.