The effects of selective response preparation on corticospinal excitability.
OBJECTIVE
Both motor imagery and selective motor cues enhance performance. Motor cortex is activated during motor imagery. We wanted to learn if selective motor cueing also activates motor cortex.


METHODS
We gave normal right-handed subjects information about which hand to use to respond to an imperative stimulus (selective intention) or where in space an imperative stimulus would occur (selective attention). To minimize anticipatory responses, warning stimulus validity was 80%. During this choice reaction time task, we recorded magnetic motor evoked potentials. Imperative stimuli and transcranial magnetic stimulation were presented randomly to assess the effect of warning cues on reaction times and corticospinal excitability.


RESULTS
Selective intentional and attentional warning cues reduced reaction times, but neither stimulus altered motor evoked potentials.


CONCLUSIONS
These results suggest that unlike motor imagery, selective intention to respond to an imperative stimulus and shifting spatial attention to an imperative stimulus do not alter corticospinal excitability.
Young
M S
MS
Human Motor Physiology Laboratory, University of Florida, Gainesville 32610-0236, USA.
Triggs
W J
WJ
Pendergast
J F
JF
Heilman
K M
KM
D000328:Adult; D002755:Choice Behavior / Q000502:physiology; D003463:Cues; D019054:Evoked Potentials, Motor; D006225:Hand / Q000502:physiology; D006801:Humans; D007092:Imagination / Q000502:physiology*; D008280:Magnetics; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D009044:Motor Cortex / Q000502:physiology*; D011712:Pyramidal Tracts / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology