Motor Imagery in Aphantasia (OLIPHANT)

Hôpital le Vinatier

Status: Enrolling

Conditions: Aphasia

Treatments: Procedure: High-definition transcranial direct current (HD-tDCS), active condition; Procedure: High-definition transcranial direct current (HD-tDCS), sham condition

Study type: Interventional

Funder types: Other

Identifiers

NCT06140940

2023-A00887-38

Details and patient eligibility

About

The present study aims to characterize and modulate motor imagery abilities in individuals with aphantasia. The investigators will characterize the neurophysiological and physiological underpinnings of mental imagery abilities in participants with aphantasia by investigating several indices of motor imagery abilities and comparing them to participants with typical mental imagery abilities. The investigators will investigate whether non-invasive brain stimulation applied to the primary motor cortex improves mental imagery abilities in participants with aphantasia.

Full description

The investigators will recruit 20 participants with aphantasia and 20 participants with typical mental imagery capacities (no-aphantasia groups). Participants in both groups will complete a 3-hour visit for inclusion and baseline measurements (Visit 1) which will include neurophysiological, autonomic nervous system, cognitive and behavioral measures.

Participants in the aphantasia group will complete 2 additional visits to receive active and sham tDCS sessions (Visit 2 and 3), according to a randomized, double-blind, sham-controlled, crossover design. Mental training will be done concurrently with tDCS using a sequential finger tapping-task (Truong et al., 2022). Participants will receive the instructions of trying to imagine themselves performing the motor task, by feeling their fingers moving as if they were actually moving it (kinesthetic modality of motor imagery).

Visits will be separated by at least 7 days.

Enrollment: 40 estimated patients

Sex: All

Ages: 18+ years old

Volunteers: Accepts Healthy Volunteers

Inclusion criteria

• For the aphantasia group only: congenital aphantasia defined as a life-long inability to generate mental imagery (confirmed by a total score of 32 or less on the VVIQ, which is the gold standard questionnaire for aphantasia)
• For the no-aphantasia group only: typical mental imagery capacities (confirmed by a total score of more than 32 on the VVIQ)
• Covered by public health insurance
• Understanding the French language
• Signed written informed consent after being informed about the study

Exclusion criteria

• Presence or history of a somatic, neurologic, or mental illness
• Actual pain or musculoskeletal disorders at the upper limb
• Having a regular musical activity (more than once a week) because of high manual dexterity
• Contraindication for noninvasive brain stimulation including the presence of ferromagnetic or magnetic sensitive metal objects implanted in the head or in close proximity (e.g., brain stent, clip, cochlear implants, or stimulator)
• Pregnancy (controlled by urine pregnancy test in females without reported contraception)
• Active seizure disorder or history of seizures
• Participants under curatorship/guardianship

Trial design

Primary purpose: Basic Science

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: Triple Blind

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40 participants in 2 patient groups, including a placebo group

active stimulation group: 20 participants with aphantasia will receive a session of active HD-tDCS

Experimental group

Description:

Participants will receive a session of active HD-tDCS at a current intensity of 4 mA for a duration of 15min. The placement of electrodes will be determined to specifically target the primary motor cortex (4 x 1 montage with the anode over C4). During the stimulation, participants will be engaged in a mental training task (sequential finger tapping-task).

Treatment:

Procedure: High-definition transcranial direct current (HD-tDCS), active condition

placebo stimulation group: 20 participants with aphantasia will receive a session of sham HD-tDCS

Placebo Comparator group

Description:

High-definition transcranial direct current (HD-tDCS), sham condition. Participants will receive a session of sham HD-tDCS, which will be delivered following the same procedures as active HD-tDCS but the intensity of the current will be set at 4mA during the 30 first seconds at the beginning of the 15-min period of the stimulation, and equal to 0 mA for the reminding period of stimulation to simulate the tingling sensation often experienced by individuals during active stimulation. The placement of electrodes will be determined to specifically target the primary motor cortex (4 x 1 montage with the anode over C4). During the stimulation, participants will be engaged in a mental training task (sequential finger tapping-task).

Treatment:

Procedure: High-definition transcranial direct current (HD-tDCS), sham condition