Russian Scientists Suggest New Diagnostic Method for Patients with Disorders of Consciousness

12:55, January 22, 2018

The acquired results will help physicians and scientists better predict disease progression in patients, including those in vegetative state.

A team of scientists from Ural Federal University (UrFU) and University of Tübingen studied the peculiarities of classical conditioning in people with disorders of consciousness. The acquired results will help physicians and scientists better predict disease progression in patients, including those in vegetative state. The study was published in  Neurobiology of Learning and Memory journal.

Disorders of consciousness are conditions in which a person looses an ability to perceive the reality objectively. One of the most serious and life-threatening impairments of consciousness is vegetative state when all consciousness is lost, and there are no or almost no reflects or reactions to external stimuli. In an experimental study the team of scientists emulated the work with patients in VS.

“Usually we give a test participant a certain task, for example, to press buttons, to find an object on screen, or to solve a recognition problem. After a task is given, a person needs some time to learn how to do it properly. Judging by the number of mistakes or the speed of reaction, we can evaluate this person’s learning progress. But when we have to deal with patients that are incapable of conscious response, the training process may be traced only by brain reactions. We monitor their brain activity and conclude whether learning took place or not,” said Yuri Pavlov, a co-author of the study, head of scientific and training laboratory of neurotechnologies and teacher assistant of clinical psychology and psychophysiology department of UrFU.

63 healthy participants were involved in the study. They listened to a sequence of sounds, and there were no additional tasks for them to fulfill. The sounds differed by key and were associated either with a participant’s or other person’s name. The scientists assumed the one’s personal name may cause a positive reaction. During the experiment the specialists registered evoked brain potentials – small-amplitude changes in brain electrical activity that appear in response to a stimulus. The team found out that after a name in combination with a certain key sound was presented to a participant several times, learning took place (i.e. a classical conditioning association was built), and after that brain reaction appeared after the sound alone.

“Studying learning processes in people with disorders of consciousness including patients in VS or in minimally conscious state will help scientist produce more accurate diagnoses and outlooks of changes in a patient’s state. Studies of this kind are limited, and no similar experiments have even been conducted before. If after completing our tests patients show signs of learning, it would mean that their brains preserved the capacity for acquiring new information and cognitive activities. For doctors it is a great ground for a positive prognosis. Therefore, our new approach will help predict disease progression in patients,” commented Yuri Pavlov.