Abstract
The direct corticomotoneuronal connection, which is highly developed in primates, is supposed to play a role in the control of individual finger movements. To clarify the neuronal mechanism of the functional recovery from the lesion of corticospinal tract (CST), we measured the regional cerebral blood flow (rCBF) by positron emission tomography (PET) using H215O in two monkeys before and after CST lesion at the C5 level. After CST lesion, pre-shaping with both the index finger and thumb was impaired and, therefore, precision grip was triggered by touching the object with the index finger. The dexterous finger movements such as precision grip started to recover in 1-4 weeks and success rate of precision grip totally recovered in 1-3 months. One month after the lesion, significant increases of rCBF in bilateral sensorymotor cortex, contralesional SMA, ipsilesional putamen and cerebellum were observed when the lesional hand was used. After 3 months, rCBF in bilateral ventral premotor cortex and bilateral senorymotor cortex were increased as compared with preoperation. These results indicate that individual finger movements such as precision grip could recover without direct corticomotoneuronal connection, and also suggest that bilateral sensorymotor cortex might be involved in compensatory mechanisms of functional recovery after the CST lesion at C5. [Jpn J Physiol 55 Suppl:S175 (2005)]
