Postlesion recovery of motor and sensory cortex in the early twentieth century.

This article addresses early work on partial recovery that followed small motor cortical lesions. Leyton and Sherrington (1917) studied the motor cortex in apes, hoping to learn more about the contralateral muscle representations. Then they placed small lesions within the precentral cortex, followed by a loss of the contralateral muscle twitches. The sudden loss remained for about one week, but recovery was observed and continued for weeks, up to a standstill. Sherrington and Graham Brown (1913) observed the same results in a serial, chronic experiment on a chimpanzee. The brain was sent to Monakow's Brain-Institute in Zurich for investigating the lesions and the degeneration pattern. Constantin von Monakow (1853-1930) had been a pioneer on recovery after acute lesions, coining the term "diaschisis." During WWI, Graham Brown and Stewart (1916) studied a soldier in a British army hospital who suffered from a cerebral gunshot wound, localized in the sensorimotor cortex. Early and prolonged rehabilitation was successful. In 1950, Glees (1909-1999) and Cole (Oxford) placed a small motor-cortical lesion in macaque monkeys; for a few days, the monkeys had difficulties and were slow for the task. Daily training was resumed and recovery was accelerated by alimentary reward. Finally, Lashley (1890-1958) understood that handicapped patients "achieved their goal with variable means." This demonstrated the value of active and prolonged rehabilitation, in addition to the (passive) recovery of function.