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Abstract:
Learning to type involves the acquisition of a mental
representation of a keyboard "map." Previous functional
neuroimaging studies have emphasized the neural systems supporting
motor sequence learning using overlearned maps, i.e., skilled
typists using standard keyboards or simplified keyboards with
fingers identified with sequential numbers. In this whole brain,
event-related fMRI study, we examined motor sequencing in the
context of learning a novel keyboard. Fifteen subjects typed one of
four possible 4-letter consonant strings using a 4-button keyboard.
The keyboard map and letter strings were presented visually.
Subjects were imaged over 8 blocks of 24 trials each. Reaction time
(time from stimulus onset to first keypress) did not improve
significantly over the 8 blocks (p>0.05); in contrast, movement
time (sum of the inter-response times) improved significantly
(p<0.0001). Functional imaging results indicated
learning-related decreases in activation in the bilateral
somatosensory cortex, bilateral frontal eye fields, left inferior
frontal gyrus, and right posterior parietal cortex.
Learning-related increases in activity were observed in the right
anterolateral cerebellum, anterior cingulate, and posterior
cingulate. These findings suggest that early phases in the
acquisition of keyboard skills predominately involve cortical
regions mediating kinematic movements in extrapersonal space, eye
movements, subvocal rehearsal, and proprioception. As the knowledge
of the keyboard becomes overlearned, performance becomes more
reliant on the cerebellum and cingulate, two structures thought to
mediate the execution of automatized movement sequences.
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