Table 2.
Brain areas | Side | X Y Z | Z score | P value |
---|---|---|---|---|
a. All stimuli types (irrespective of the light and prosody conditions) | ||||
SAD > Controls | ||||
Thalamus 1 | R | 14 −18 4 | 3.61 | 0.010 |
Brainstem 1 | L | −2 −28 −22 | 3.58 | 0.011 |
Controls > SAD | ||||
No significant voxel | ||||
b. Anger prosody stimuli | ||||
[Blue > dark] × [SAD > Controls] | ||||
Hypothalamus 2, 4 | L | −2 −2 −12 | 3.21 | 0.027 |
[Blue > dark] × [Controls > SAD] | ||||
No significant voxel | ||||
[Green > dark] × [SAD > Controls] | ||||
No significant voxel | ||||
[Green > dark] × [Controls > SAD] | ||||
Hypothalamus 3, 4 | L | −4 −2 −18 | 3.13 | 0.032 |
XYZ: relative coordinates (mm) in MNI space.
The same two significant clusters of voxel are obtained in the thalamus and brainstem if the analyses only included 1) all stimuli in darkness; 2) all stimuli under green light exposure; 3) all stimuli under blue light exposure; 4) emotional stimuli under blue or green light exposure ; 5) neutral stimuli in under blue or green light exposure (i.e. theses differences between groups are observed for every stimuli subgroups).
Clusters not affected by an exclusive mask (p=0.05) of the (Neutral × [Blue > dark] × [SAD > Controls]) contrast, indicating that the light condition effect was specific to the emotional (angry prosody) stimuli.
Clusters not affected by an exclusive mask (p=0.05) of the (Neutral × [Green > dark] × [SAD > Controls]) contrast, indicating that the light condition effect was specific to the emotional (angry prosody) stimuli.
Because of the difference in irradiance level between blue and green light (see technical issue in the methods section) the contrast computing the interaction between blue and green light conditions [(Blue > Green)] × [SAD > Controls] is not valid. However, if this contrast is nevertheless computed, it shows a single significant difference in the hypothalamus (−2 0 −18 mm; Z = 3.73; psvc = 0.006) which further strengthens the results obtained for each light condition separately.