Motor sequence learning with the nondominant left hand. A PET functional imaging study.

Area of Science:

• Neuroscience
• Motor Control
• Cognitive Neuroscience

Background:

• Hemispheric asymmetry exists in motor control, with the left hemisphere active for both contralateral and ipsilateral movements.
• The role of this asymmetry during motor learning, particularly implicit sequence learning, is not well understood.

Purpose of the Study:

• To investigate hemispheric involvement during implicit motor sequence learning using the nondominant left hand.
• To examine brain activity patterns associated with sequence learning and transfer.

Main Methods:

• Functional brain imaging (fMRI) was used to monitor brain activity during the serial reaction time (SRT) task.
• Subjects learned an implicit motor sequence with their left hand, followed by testing with the right hand using original and mirror-ordered sequences.

Main Results:

• Implicit sequence learning with the left hand increased activity in the left premotor cortex (PMC) and supplementary motor areas (SMA), with greater activation in the left hemisphere.
• Learning engaged widespread temporal and frontal regions, indicating involvement of cognitive and motor networks.
• Right-hand performance on the original and mirror sequences showed significant improvement over random stimuli.
• Mirror transformation during right-hand performance led to increased left motor cortex activity.

Conclusions:

• The left hemisphere, particularly the SMA, is critical for representing motor sequences independently of the effector limb.
• Motor skill learning with the nondominant hand involves integrated cognitive and motor networks.
• The left motor cortex plays a role in the sequential transformation of learned motor patterns.