Spaced Versus Massed Skill Learning
Condition: Healthy Volunteer
Study type: Observational

Summary: 
      This study will explore the optimum training schedule for stroke patients to learn motor
      skills. It will see if motor training is more effective when training sessions are
      distributed over time (spaced training) or when the sessions are scheduled close together
      (massed training). The results of this study may help researchers devise the best training
      schedule for patients to derive the maximum benefit from rehabilitation therapy.

      Healthy normal volunteers and people who have had a stroke may be eligible for this study.
      Patients must be 3 months post-stroke. All participants must be right-handed and between 18
      and 80 years of age.

      Participants practice a pinch motor task and receive transcranial magnetic stimulation (TMS).
      Hand muscle activity is measured using surface electromyography (EMG). Pinch training
      involves training the participant to pinch as strongly as possible, using a device that
      records the force. For TMS, a wire coil is held on the subject s scalp. A brief electrical
      current is passed through the coil, creating a magnetic pulse that stimulates the brain. The
      subject hears a click and may feel a pulling sensation on the skin under the coil. There may
      be a twitch in the muscles of the face, arm or leg. For surface EMG, electrodes (small metal
      disks) are filled with a conductive gel and taped to the skin over the muscle.

      Following one practice session of pinch task training and TMS, participants have four
      training sessions, which are scheduled 24 hours, 2 weeks, 1 month and 3 months after the
      practice session.

      For the 4- to 5-hour practice session, subjects do the following:

        -  Perform a single session of pinch motor task for familiarization

        -  Undergo TMS to measure brain activity

        -  Practice five 6-minute blocks of pinch motor task with rest periods between sessions and
           perform a calculation task (addition and subtraction tasks) during each rest period

        -  Receive TMS over 15 minutes. (Some sessions may have sham TMS.)

        -  Read books and magazines during a 45-minute rest period

        -  Perform a single block of the pinch motor task

        -  Undergo TMS to measure brain activity

        -  Complete a questionnaire that measures attention, fatigue and mood

      For the remaining four sessions, participants perform one practice block and TMS. Each
      session lasts about 2 hours.
    

Detailed description: 
      In cognitive psychology, practice is most effective when training sessions are distributed
      over time (spaced), rather than when they are close to each other (massed). This phenomenon,
      thought to engage long-term potentiation-like mechanisms in animal models and described as
      spacing effect, has not been investigated in the motor domain. It is not known if spaced
      motor training elicits longer lasting learning effects than massed motor training.

      Objective and Study Population:

      The purpose of this investigation is to assess the relevance of the spacing effect in motor
      skill learning in healthy volunteers and in patients with chronic stroke.

      Design:

      Experiment 1: Determination of long term learning in healthy volunteers with spaced and
      massed practice:

      The first hypothesis is that spaced practice will enhance long-lasting learning of a motor
      task (defined as performance improvements measured 1 and 3 months post training) to a larger
      extent than massed practice in separate groups of healthy volunteers. Healthy volunteers will
      practice a well-characterized pinch force task following spaced or massed schedules in a
      factorial design (n=26). If this hypothesis is proven correct, we will proceed as suggested
      by PIRC, to Experiments 2 and 3, to gain information on the mechanisms underlying the
      superior training strategy in healthy volunteers (Exp 2) and to determine if this training
      strategy is also superior to massed practice in stroke patients (Exp 3), an issue of crucial
      importance in neurorehabilitation.

      Experiment 2: Study of mechanisms underlying superior effects of spaced over massed practice
      in healthy volunteers, rTMS:

      Previous work demonstrated the involvement of the primary motor cortex (M1) in consolidation
      of motor learning and the importance of top-down attentional control by the prefrontal
      cortex. It is possible that an enhanced recruitment of these two regions mediates the
      superior performance levels reached with spaced training. Here, we plan to study the effects
      of inhibitory 1 Hz TMS applied to M1 and PFC on performance improvements with spaced
      training. We hypothesize that the superiority of spaced practice, relative to massed
      practice, will be cancelled by down regulation of activity in M1 and PFC but not by sham or
      posterior parietal cortex (PPC) stimulation (n=104).

      Experiment 3: Determination of long term learning in stroke patients with spaced and massed
      practice:

      We hypothesize that motor learning in chronic stroke patients will improve to a larger extent
      with spaced than with massed practice (n=42).

      This study is expected to delineate the role of the spacing effect on human motor learning
      and identify two of the possible neural cortical substrates in healthy volunteers and its
      possible beneficial effects on motor learning after stroke.

      Experiment 4: Determination of whether original findings with the spacing effect in explicit
      motor learning generalized to implicit/procedural motor learning:

      The ability to generalize to implicit motor learning is important because implicit learning
      (also known as procedural learning), which is defined as learning which occurs without
      awareness and without intention, underlies the development of automaticity which
      characterizes all well-learned motor skills (Reber, 1993; Squire, 2004). Hence, for the
      purposes of stroke rehabilitation, it is important to determine if and how the spacing effect
      occurs for implicit (procedural) learning which underlies the development of automaticity
      that characterizes all well-learned motor skills. In addition, using explicit motor
      sequencing tasks, it is difficult to determine if the spacing effect helps general motor
      skill or sequence-specific skill. In other words, performance benefits from the spacing
      effect can derive from improvements in the visuomotor transformation required to push the
      keys on the board independently of the presence or absence of sequence, or from motor
      sequencing improvements. Both of these issues can be addressed using the serial reaction time
      task (or SRTT), a well-studied implicit motor sequence learning task which is described in
      more detail in this protocol (Nissen and Bullemer, 1984).

      We hypothesize that the spacing effect occurs in a sequence-specific manner for implicit
      motor sequence learning. We hypothesize that an SMA-based motor network underlies the
      superiority of the spacing effect for implicit motor sequence learning. We will show this by
      using 1Hz TMS to create virtual lesions and establish a cause-effect link between the SMA (or
      M1 but not CZ or sham) and superior motor skill with Spaced over Massed training (n=80).

      Outcome Measures:

      The primary outcome measure will be improvement in pinch force. Secondary outcome
      measurements will be measures of motor cortical excitability including motor evoked potential
      amplitudes, intracortical inhibition and facilitation.

      For procedural/implicit motor sequence learning, the primary outcome measure will be an
      improvement in skill as seen by a difference in reaction time between sequenced and randomly
      ordered trials.
    

Keywords: Motor Practice; Magnetic Stimulation; Stroke; Spacing Effect; Massed Practice; Healthy Volunteer; HV