Motor Imagery in Aphantasia

Official title

Probing and Modulating Motor Imagery Capacities in Aphantasia

Overview

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.

Detailed 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.

Interventions

• Procedure High-definition transcranial direct current (HD-tDCS), active condition
  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).
• Procedure 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 m

Primary outcome measures

• Gains in motor performance following mental training [Time frame: 2 times: immediately before tDCS (baseline) and immediately after tDCS]

Secondary outcome measures (11)

• Motor corticospinal excitability at rest and during kinesthetic motor imagery [Time frame: 1 time at baseline (Visit 1), in both groups]
• Heart rate variability [Time frame: through study completion, an average of 1 month]
• Skin conductance [Time frame: through study completion, an average of 1 month]
• Mental imagery abilities [Time frame: 1 time at baseline, in both groups]
• Mental imagery abilities [Time frame: 1 time at baseline, in both groups]
• Mental imagery abilities [Time frame: 1 time at baseline, in both groups]
• Mental imagery abilities [Time frame: 1 time at baseline, in both groups]
• Mental imagery abilities [Time frame: 1 time at baseline, in both groups]
• Source monitoring performance [Time frame: 1 time at baseline, in both groups]
• Implicit motor imagery capacities [Time frame: 1 time at baseline, in both groups]
• Performance of time-to-contact estimation [Time frame: 1 time at baseline, in both groups]

Eligibility criteria

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

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: Yes

Study design

Allocation

Randomized

Model

Crossover

Masking

Triple blind

Primary purpose

Basic science

Study locations

France · 1 center

• Centre Hospitalier le Vinatier — Bron

Identifiers

NCT: NCT06140940 · 2023-A00887-38

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗