The objectives of this scientific expedition are: a/ Evaluation of temporal cognitive perception and collective synchronization in a temporally anomalous universe (underground environment), b/ Influence of group living on the endogenous circadian rhythmicity of the central biological clock and peripheral clocks in a "free-running" situation (absence of light/natural darkness), c/Evaluation of cognitive and physiological performance in response to exposure to an extreme environment in a natural underground cavity (cave) without access to a time indicator for 40 days, d/Correlation of cognitive, behavioral, psychological, social, neurophysiological and physiological parameters, e/ Determination of adaptation or maladaptation criteria (biological, genetic, physiological, neurophysiological, psychological and cognitive) in an isolation environment (underground) f/ Study of the evolution of collective organization, decision making and leadership in an extreme isolation and management situation.

This exceptional period has shown a significant desynchronization and loss of notion of time in a large number of people as well as important questions about human abilities to live in confined conditions. It is partly for this reason, but also to answer more fundamental questions on the perception of time that the extraordinary research expedition Deep Time was conceived: 40 days underground to know the links of our brain to time and synchronization within a group. A fundamental need for our future. This scientific expedition will take place entirely in France to ensure the feasibility and safety of the subjects and experimenters, under the direction of Christian Clot and the Institute of Human Adaptation, placed under the high patronage of the Ministry of Education, Research and Innovation.

The project addresses the fundamental question of human adaptation to the physical environment and the crucial role of the brain's neuroplasticity properties.

The present "Deep-Time" protocol naturally echoes the "out-of-time" isolation experiments conducted by the speleologist Michel Siffre starting in 1962 and its various components in the years that followed.

These "out of time" experiments led to certain conclusions. As curious as it may seem, in the absence of the time givers (synchronizers or Zeitgebers in German) that are the social rhythms and the day-night alternations, the spontaneous rhythm would settle on a rhythm of about 25 hours.

However, these experiments remained limited to isolated individuals, in conditions of spatial unity (no displacement outside of the work camps), leaving a whole field of research and questioning that the year 2021 has strongly emphasized.

The objectives of this scientific expedition are: a/ Evaluation of temporal cognitive perception and collective synchronization in a temporally anomalous universe (underground environment), b/ Influence of group living on the endogenous circadian rhythmicity of the central biological clock and peripheral clocks in a "free-running" situation (absence of light/natural darkness), c/Evaluation of cognitive and physiological performance in response to exposure to an extreme environment in a natural underground cavity (cave) without access to a time indicator for 40 days, d/Correlation of cognitive, behavioral, psychological, social, neurophysiological and physiological parameters, e/ Determination of adaptation or maladaptation criteria (biological, genetic, physiological, neurophysiological, psychological and cognitive) in an isolation environment (underground) f/ Study of the evolution of collective organization, decision making and leadership in an extreme isolation and management situation.

Inclusion Criteria:

Strictly right-handed Good health without any medical and psychiatric diseases No contraindications to MRI French or European nationality Not to be included in another biomedical protocol

Exclusion Criteria:

Being pregnant Minor, under guardianship or curatorship