Motor Imagery in Aphantasia
ConditionAphasia
Trial statusRecruiting
Trial phaseNot applicable
Trial typeInterventional
Biological sexAll
Age18+
SponsorHôpital le Vinatier
About this trial
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.
Eligibility criteria
This trial accepts healthy volunteersQualifiers
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
Disqualifiers
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)
Trial design
Design model
Crossover
Treatments tested in this trial
High-definition transcranial direct current (HD-tDCS), active condition
Procedure/SurgeryParticipants 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).
High-definition transcranial direct current (HD-tDCS), sham condition
Procedure/SurgeryParticipants 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 groups
40 Participants
are divided into 2 treatment groupsGroup A: active stimulation group: 20 participants with aphantasia will receive a session of active HD-tDCSExperimental treatment 1 intervention
Group B: placebo stimulation group: 20 participants with aphantasia will receive a session of sham HD-tDCSPlacebo comparator 1 intervention
Trial outcomes
Primary outcomes
1
Gains in motor performance following mental training
Gains in motor performance following mental training combined with tDCS will be measured using a sequential finger tapping-task. Gains following training will be expressed as a percentage of the baseline performance.
Time frame
2 times: immediately before tDCS (baseline) and immediately after tDCSSecondary outcomes
1
Motor corticospinal excitability at rest and during kinesthetic motor imagery
Motor corticospinal excitability will be assessed with single-pulse transcranial magnetic stimulation (TMS) applied over the primary motor cortex representation of the non-dominant hand. Using electromyography, we will measure the peak-to-peak mean amplitude of motor evoked potentials (MEPs, measured in mV) in the contralateral first dorsal interosseous muscle both at rest and during kinesthetic motor imagery.
Time frame
1 time at baseline (Visit 1), in both groups2
Heart rate variability
Heart rate variability, including respiratory sinus arrhythmia measures, expressed in milliseconds (ms), will be assessed at rest and during kinesthetic motor imagery by recording the heart rate using three electrodes placed in the left chest area. These electrodes will be connected to the Biopac MP150 system and monitored with the Acqknowledge software
Time frame
through study completion, an average of 1 month3
Skin conductance
Amplitude of electrodermal response will be measured at rest, during actual movements and during kinesthetic motor imagery using the Biopac MP150 system with the Acqknowledge software. The ratio between amplitudes during imagined/actual movements will be computed (expressed in percent).
Time frame
through study completion, an average of 1 month4
Mental imagery abilities
Mental imagery abilities in different sensory modalities will be measured as scores at the following questionnaires: Vividness of Visual Imagery Questionnaire (VVIQ; range 16-80)
Time frame
1 time at baseline, in both groupsSponsors and contacts
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Source ClinicalTrials.gov