Somepatients in a vegetative or minimally conscious statehavelearning capacity, as revealed by a study published in the journalNature Neuroscience.
The authors, scientists from the universities of Buenos Aires (Argentina) and Cambridge (United Kingdom), have also determined that the patients who show the greatest learning capacity are those who normally achieve a greater recovery.
They reached this conclusion after conducting a series of experiments with 22 subjects admitted in a vegetative state in Buenos Aires hospitals, to whom they were connectedelectrodesaround the eye muscles and glasses with a small tube through which air was blown. By means of a computer, a sound signal was emitted for an instant and a half second, then air was thrown through the tube towards one of the eyes of the patients, most of which responded to the stimulus.
The experiment, similar to the “conditioned reflex” experiment carried out in animals by Russian physiologist Ivan Pavlov last century, showed that8 of the 22 patients learned very quickly that they had to close their eye following the sound signal. Of the rest, 6 patients offered partial answers, and the remaining 8 did not learn anything, he said. According to Tristán Bekinschtein, co-author of the study, the same experiment was carried out in patients under the effects of general anesthesia without detecting a response to the stimulus, which shows that this system does not work when the person is totally unconscious.
The patients who were able to learn the best were those who were in a vegetative or minimally conscious state after suffering a skull fracture in an accident, while those who suffered a cerebrovascular accident showed very little or no level of learning. The learning capacity in this type of patients would allowpredict the chance of recovery with 86 percent accuracy, according to Mariano Sigman, director of the Laboratory of Integrative Neuroscience of the Faculty of Exact and Natural Sciences of the University of Buenos Aires.
