Illuminance impact on the hypothalamus subparts.
(A) Segmentation of the hypothalamus in five subparts in a representative participant. The nuclei encompassed by the different subparts are indicated in the right inset – according to 8. ARC: arcuate nucleus; DMH; dorsomedial nucleus; LH lateral hypothalamus; LTN: lateral tubular nucleus; MB: mamillary body; POA: preoptic area; PVN: paraventricular nucleus; PNH: posterior nucleus of the hypothalamus; SCN: suprachiasmatic nucleus; SON: supraoptic nucleus; TMN: tuberomammillary nucleus; VMN: ventromedial nucleus
(B-C) Estimates (beta; arbitrary unit – a.u.) of the collective impact of illuminance variation on the activity of each hypothalamus subpart. (Refer to Table 1 full statistics)
(B) Executive task: significant main effect of hypothalamus subparts (p=0.002), no significant main effect of task type (p=0.4) or subpart-by-task-type interaction (p=0.61).
(C) Emotional task: significant main effect of hypothalamus subparts (p<.0001), no significant main effect of stimulus type (p=0.053) or subpart-by-stimulus-type interaction (p=0.7).
(D-G) Whole brain analyses of the collective impact of the variations in illuminance over the hypothalamus area - for illustration.
A local positive peak (red; puncorrected<0.001) was detected over the posterior hypothalamus subpart (light blue) in executive (E) and emotional (G).
A local negative peak (red; puncorrected<0.001) was detected over the inferior-tubular hypothalamus subparts (light orange) during the executive task (D), while local negative peak (red; puncorrected<0.001) was detected over the inferior-anterior (yellow) and superior-anterior §blue) hypothalamus subparts during the emotional task (F) – insets correspond to enlargements over the hypothalamus area.
Arrows from panels B and C arise from and are colour coded according to the hypothalamus subpart that is displayed in panels D to G.
These results indicate that our finding does not arise from a nearby “leaking” activation/deactivation.
(I-L) Estimates of the impact of each illuminance on the activity of the hypothalamus subparts. (Refer for Table 2 and Suppl. Tables S3-S7 for full statistics)
Activity dynamics across illuminance for each subpart (colour code as in A). Results are displayed per task or stimulus type although no interactions with task or stimulus type were detected. Significant illuminance-by-hypothalamus-subpart interactions were detected for (I-J) the executive task (p=0.041) and (K-L) the emotional task (p=0.041).
Small letter indicate significant difference (p < 0.05) between the following subparts at illuminance: a. 92 mel EDI lux: posterior vs. superior-anterior; posterior vs. inferior-tubular; b. 190 mel EDI lux: posterior vs. superior-anterior; posterior vs. inferior-tubular; c. 0 mel EDI lux: posterior vs. superior-tubular; d. 92 mel EDI lux: posterior vs. superior-anterior; superior-anterior vs. inferior-tubular; e. 190 mel EDI lux: posterior vs. inferior-anterior; posterior vs. superior-anterior; posterior vs. inferior-tubular; superior-anterior vs. superior-tubular; inferior-tubular vs. superior-tubular.