Spaced Versus Massed Skill Learning

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.

- INCLUSION CRITERIA: Healthy Volunteers

- Age between 18-80 years

- Able to perform tasks required by the study

- Willing and able to give consent

- Have a normal physical and neurological examination

- Right Handed as assessed by the Edinburgh inventory scale (Edinburgh, 1971)

EXCLUSION CRITERIA: Healthy Volunteers

- History of alcohol or drug abuse, and psychiatric illness such as severe depression.

- Receiving drugs acting primarily on the central nervous system, which lower the
seizure threshold such as antipsychotic drugs (chlorpromazine, clozapine) or tricyclic
antidepressants.

INCLUSION AND EXCLUSION CRITERIA FOR STROKE PATIENTS:

Patients must be between the ages of 18 and 80 years of age, inclusive. Included will be
those with chronic (more than 3 months) stroke who recovered motor function to the point of
being able to perform the ballistic pinch force task. Stroke patients will be recruited
through the NIH Clinical Research Volunteer Program. Assessment of severity of initial
hemiparesis will be taken either from patient report or medical records.

EXCLUDED FROM THE STUDY WILL BE PATIENTS:

1. with a history of severe alcohol or drug abuse, psychiatric illness like severe
depression, severe language disturbances, particularly of receptive nature or with
serious cognitive deficits (defined as equivalent to a mini-mental state exam
(Folstein, 1976) score of 23 or less)

2. with severe uncontrolled medical problems (e.g., cardiovascular disease, severe
rheumatoid arthritis, active joint deformity of arthritic origin, active cancer or
renal disease, any kind of end-stage pulmonary or cardiovascular disease, or a
deteriorated condition due to age, uncontrolled epilepsy or others)

3. with metal in the body (metal in the cranium, metal fragments from occupational
exposure, surgical clips in or near the brain, cardiac or neural pacemakers,
intracardiac lines, implanted medication pumps, blood vessel, cochlear or eye
implants)

4. with history of loss of consciousness or epilepsy

5. with history of hyperthyroidism or individuals receiving drugs acting primarily on the
central nervous system, which lower the seizure threshold such as antipsychotic drugs
(chlorpromazine, clozapine) or tricyclic antidepressants.