Cerebellar tDCS on Motor Learning of Healthy Individuals
Condition: Healthy
Study type: Interventional

Summary: 
      A crossover trial with healthy volunteers will be conducted. Three sessions will be performed
      with at least 48 hours washout period to minimize carry-over effects. In each session,
      volunteers will be submitted to: fatigue and attention levels evaluation, handwriting test,
      serial reaction time task (SRTT) before and after ctDCS conditions and after session, a
      performance perception evaluation.
    

Detailed description: 
      A crossover, pseudo-randomized, sham-controlled and triple blind will be performed in order
      to evaluate ctDCS effects on motor learning, since evidence pointed to the crucial role of
      cerebellum on motor behavior. A non-involved research will conduct a pseudo-randomization
      (www.randomization.com) to warrant the counterbalanced sessions order and the allocation
      concealment. Volunteers, researchers and statistical analysis will be blinded to ctDCS
      condition.

      After given prior informed consent, volunteers will be submitted to three experimental
      sessions: anodal ctDCS, cathodal ctDCS and sham ctDCS. Fatigue and attention levels,
      handwriting test and SRTT will be performed before and after stimulation. In addition,
      performance perception evaluation will be assessed at the end of session.

      Electrical current will be delivered through a DC stimulator (NeuroConn Plus, Germany) using
      a pair of saline-soaked sponge electrodes (surface 35cm²). The active electrode (anode or
      cathode) will be placed over the left cerebellum (3 cm lateral to the inion) and the
      reference, over the left arm with current intensity of 2mA, fade in and fade out of 10
      seconds, during 20 minutes. Sham tDCS has been used in several studies to evaluate active
      tDCS effects.

      Sham ctDCS will be applied using the same electrodes placement and parameter settings of
      cathodal ctDCS however, stimulation will last only 30 seconds but volunteers will be with
      electrodes montage for 20 minutes. Because the device will be automatically turned off
      without volunteer's perception, early sensations (mild to moderate tingling) on stimulation
      site will be experienced without inducing any modulatory effects. Moreover, after each ctDCS
      session, an adverse effects questionnaire will be applied.

      Fatigue and attention levels will be measured through an analogue scale graded from 0 to 10,
      where 0 means lower fatigue or attention levels and 10, the higher fatigue or attention
      levels.

      Handwriting test: volunteers will be instructed to write six words with digital pen using the
      non-dominant hand on a tablet provided with analysis software system (MovAlyzer, EUA). The
      task will be performed spontaneously, without any instruction bias during writing activity.
      Each session has different word sequences but the difficulty level will be maintained (six
      words, two of them with 4, 6 and 8 letters).

      SRTT: will be performed through software with visual stimuli presented on a computer screen
      in four different positions. Volunteer must press, with the non-dominant hand, a
      corresponding key with a predetermined finger as soon as possible when a highlighted star
      appears on the screen. The test comprises eight blocks with 120 trials each. Implicit motor
      learning is measured by performance changes between the blocks 5, 6 and 7.

      Performance perception evaluation: in order to correlate stimulation type to the conscious
      improvement on motor task performance (SRTT and handwriting test) will be asked in the end of
      each session: "Regarding today's session, comparing your motor performance before and after
      cerebellar stimulation, you consider that you were better, worse or the same as before?"
    

Intervention name(s): tDCS; tDCS; tDCS
Intervention type(s): Device; Device; Device
Intervention description(s): Current will be applied by a DC stimulator (NeuroConn Plus, Germany).The active electrode (anode: 5x7 cm²) will be placed over the left cerebellar hemisphere (3 cm lateral to the inion) and the reference (5x7 cm²), over the left arm with current intensity of 2mA, fade in and fade out of 10 seconds, during 20 minutes.; Current will be applied by a DC stimulator (NeuroConn Plus, Germany). The active electrode (cathode: 5x7 cm²) will be placed over the left cerebellar hemisphere (3 cm lateral to the inion) and the reference (5x7 cm²), over the left arm with current intensity of 2mA, fade in and fade out of 10 seconds, during 20 minutes.; Sham ctDCS (NeuroConn Plus, Germany) will be applied at the same parameter settings used on cathodal ctDCS however, current duration will be only 30 seconds. Moreover, device automatically turned off without volunteer's perception, but volunteers will be with electrodes montage for 20 minutes.
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary purpose: Treatment
Keywords: Cerebellum; Transcranial Direct Current Stimulation; Motor Learning; Serial Reaction Time Task; Handwriting