Endogenous modulation of human visual cortex activity improves perception at twilight

• Published in: Nature communications Vol. 9; no. 1; pp. 1274 - 9
• Main Authors: Cordani, Lorenzo, Tagliazucchi, Enzo, Vetter, Céline, Hassemer, Christian, Roenneberg, Till, Stehle, Jörg H, Kell, Christian A
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 10.04.2018; Nature Publishing Group UK; Nature Portfolio
• Subjects: Adult; Brain; Brain Mapping; Circadian rhythm; Circadian rhythms; Cortex (somatosensory); Functional magnetic resonance imaging; Humans; Magnetic Resonance Imaging; Male; Modulation; Parietal Lobe - anatomy & histology; Parietal Lobe - diagnostic imaging; Parietal Lobe - physiology; Perception; Photoperiod; Signal quality; Somatosensory Cortex - anatomy & histology; Somatosensory Cortex - diagnostic imaging; Somatosensory Cortex - physiology; Temporal Lobe - anatomy & histology; Temporal Lobe - diagnostic imaging; Temporal Lobe - physiology; Time of use; Twilight glow; Visual cortex; Visual Cortex - anatomy & histology; Visual Cortex - diagnostic imaging; Visual Cortex - physiology; Visual perception; Visual Perception - physiology; Visual signals; Visual thresholds
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-018-03660-8

Perception, particularly in the visual domain, is drastically influenced by rhythmic changes in ambient lighting conditions. Anticipation of daylight changes by the circadian system is critical for survival. However, the neural bases of time-of-day-dependent modulation in human perception are not yet understood. We used fMRI to study brain dynamics during resting-state and close-to-threshold visual perception repeatedly at six times of the day. Here we report that resting-state signal variance drops endogenously at times coinciding with dawn and dusk, notably in sensory cortices only. In parallel, perception-related signal variance in visual cortices decreases and correlates negatively with detection performance, identifying an anticipatory mechanism that compensates for the deteriorated visual signal quality at dawn and dusk. Generally, our findings imply that decreases in spontaneous neural activity improve close-to-threshold perception.