TY - JOUR
T1 - Writing's shadow
T2 - Corticospinal activation during letter observation
AU - Nakatsuka, Masahiro
AU - Thabit, Mohamed Nasreldin
AU - Koganemaru, Satoko
AU - Nojima, Ippei
AU - Fukuyama, Hidenao
AU - Mima, Tatsuya
PY - 2012/5
Y1 - 2012/5
N2 - We can recognize handwritten letters despite the variability among writers. One possible strategy is exploiting the motormemory of orthography. By using TMS, we clarified the excitatory and inhibitory neural circuits of the motor corticospinal pathway that might be activated during the observation of handwritten letters. During experiments, participants looked at the handwritten or printed single letter that appeared in a random order. The excitability of the left and right primary motor cortex (M1) was evaluated by motor-evoked potentials elicited by single-pulse TMS. Short interval intracortical inhibition (SICI) of the left M1 was evaluated using paired-pulse TMS. F waves were measured for the right ulnar nerve. We found significant reduction of corticospinal excitability only for the right hand at 300-400msec after each letter presentation without significant changes in SICI. This suppression is likely to be of supraspinal origin, because of no significant alteration in F-wave amplitudes. These findings suggest that the recognition of handwritten letters may include the implicit knowledge of "writing" in M1. The M1 activation associated with that process, which has been shown in previous neuroimaging studies, is likely to reflect the active suppression of the corticospinal excitability.
AB - We can recognize handwritten letters despite the variability among writers. One possible strategy is exploiting the motormemory of orthography. By using TMS, we clarified the excitatory and inhibitory neural circuits of the motor corticospinal pathway that might be activated during the observation of handwritten letters. During experiments, participants looked at the handwritten or printed single letter that appeared in a random order. The excitability of the left and right primary motor cortex (M1) was evaluated by motor-evoked potentials elicited by single-pulse TMS. Short interval intracortical inhibition (SICI) of the left M1 was evaluated using paired-pulse TMS. F waves were measured for the right ulnar nerve. We found significant reduction of corticospinal excitability only for the right hand at 300-400msec after each letter presentation without significant changes in SICI. This suppression is likely to be of supraspinal origin, because of no significant alteration in F-wave amplitudes. These findings suggest that the recognition of handwritten letters may include the implicit knowledge of "writing" in M1. The M1 activation associated with that process, which has been shown in previous neuroimaging studies, is likely to reflect the active suppression of the corticospinal excitability.
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U2 - 10.1162/jocn_a_00205
DO - 10.1162/jocn_a_00205
M3 - Article
C2 - 22332804
AN - SCOPUS:84859150987
VL - 24
SP - 1138
EP - 1148
JO - Journal of Cognitive Neuroscience
JF - Journal of Cognitive Neuroscience
SN - 0898-929X
IS - 5
ER -