Covert actions are cognitive processes that involves the motor system. They include motor imagery, movement preparation, action observation or action language. They imply mental simulations, based on activations of neural networks, involved in specific operations such as perceiving or acting. These mental phenomena have intrigued and still intrigue philosophers, psychologists, and neuroscientists, as they are complex and introspective processes, which play a major role in human cognition.

To decipher similarities and differences between these types of covert actions, the investigators will focus on persons living with aphantasia, which is a neurocognitive specificity present in a small proportion of the population (5 to 8%). Aphantasia is characterized by the alteration or the absence of explicit mental representations.

This population offers an ideal testbed to disentangle the involvement of cognitive and motor processes in different forms of covert actions.

By means of magnetoencephalography, this study aims to identify and compare brain patterns and their temporal dynamics in alpha and beta bands during covert actions in two groups of healthy volunteers: aphantasics and non-aphantasics (i.e., having a non-altered imagery capacity).

If covert actions indeed share brain networks, the investigators expect aphantasics to present reduced neural and behavioral activation during the explicit (i.e., motor imagery) and implicit (movement preparation, action language and action observation) forms of covert actions.

Inclusion Criteria:

• Aged 18 to 60 years
• Willing to actively participate in the study
• Having signed an informed consent form to participate in the study

Inclusion Failure Criteria:

Identification of individuals with and without aphantasia based on responses to a questionnaire validated in the literature: Vividness of Movement Imagery Questionnaire, second version (VMIQ-2):

Scores required for inclusion in the aphantasic group

• VMIQ-2: internal visual imagery score = 55-60
• VMIQ-2: kinesthetic imagery score = 55-60

Scores required for inclusion in the non-aphantasic group

• VMIQ-2: internal visual imagery score = 20-36
• VMIQ-2: kinesthetic imagery score = 20-36

Exclusion Criteria:

• Neurological or psychiatric disorders
• History of neurological or psychiatric disorders
• Sleep disorders that may affect data variability or quality, or participant cooperation and retention, as assessed by the principal investigator or co-investigator during the inclusion interview
• Volunteers presenting standard contraindications to MEG and MRI examinations:
• Presence of incompatible metal in the body (pacemaker, implanted pump including insulin pump, neurostimulator, cochlear implants or other hearing devices, metallic prosthesis, intracerebral/surgical aneurysm clips, implantable defibrillator, ferromagnetic foreign bodies in the eyes or brain in the upper body, ventriculoperitoneal shunt valves, dental braces or steel posts in root canals, ferromagnetic foreign bodies in the upper body)
• Claustrophobia
• Pregnant or breastfeeding women
• Individuals under guardianship, curatorship, or legal protection
• Individuals deprived of liberty
• Individuals undergoing psychiatric care
• Individuals admitted to a health or social institution for reasons other than clinical research
• Individuals not affiliated with a social security system or not beneficiaries of such a system