Severe traumatic brain injury (TBI) is the most common cause for death and chronic disability in young people. Serious post-traumatic impairments arise due to the multicomponent nature of brain injuries in these patients. Consequences of TBI are often associated with impairment in different spheres—motor, cognitive, psychological, behavioral, emotional deficits and etc. Interaction derangement of various afferent and efferent systems (visual, vestibular, sensori-motor, and others) may be the main reason for people after TBI being unable to perform different simple and complex behaviors including maintenance of vertical posture [1,2]. On the other hand, clear link of mental, cognitive and memory deficits in TBI and brain damaged patients was ascertained [3,4]. Moreover, mild traumatic TBI known as concussion as a rule also was accompanied by long-term memory and cognitive deficit [5,6]. In any cases, consequences of severe TBI may produce post-traumatic Korsakov syndrome (KS), which develops in the form of anteroand retrograde amnesia, disorientation in space and time, the emotional-personality sphere, etc. [7].

Recent advances in brain imaging methodologies have revealed important information regarding both structural and functional properties of the TBI patients [8-12]. Diffusion tensor imaging (DTI), which allows assessment of the severity of lesions to the white matter of the brain and conducting pathways of the brain, has been proposed as sensitive biomarker of TBI. A large number of researches using DTI studies in TBI patients compared with controls described reduction of fractional anisotropy of corticospinal tract, in the corpus callous and etc. [10-12].

However, traditional analysis of the brain-behavior correlation in healthy persons and in patients with different brain disorders is mostly implemented by focusing on alteration of brain signals—electroencephalogram (EEG) which is widely used in scientific researches and clinical practice [13]. Coherence analysis seems to be suitable for studying brain functions after TBI too, as it measures possible mechanisms of integration-disintegration). EEG coherence as a measure of spectral similarity may estimate cortical coupling between two signals as a function of frequency and reflect the structural connections and functional coupling between these regions [14-20].

Restoration of impaired functions in patients after severe TBI does require special rehabilitation techniques recruiting intact brain and body capacities and adaptivecompensatory potentials [21-24]. Memory and motor functions are known to be tightly interrelated as a rule. These deficiencies occur simultaneously in different types of brain pathology including TBI [25]. Neuropsychological approaches proposed by Luria and his followers are based on persisting functionality of impaired higher mental functions including memory and motor skills (especially professional) during rehabilitation [26]. Recent studies have shown that the inclusion of stabilotraining (ST) with feedback (voluntary postural training) into TBI rehabilitation programs is an effective operant approach promoting the recovery of postural skill [21-24]. Our previous data and results of other studies demonstrated restoration not only motor, but also memory functions due to ST as a special rehabilitation method [27,28]. This rehabilitation approach was based on Luria’s hypothesis that motor memory was the most ancient type of memory. The motor (or postural) training may build up the basement for the recovery of more complex forms of behavior [22-25].

In previous studies, we used complex evaluation of patients’ condition including quantitative clinical assessment scales, stabilographic and EEG coherence measures that were highly informative in following rehabilitation effects [27,28]. Now we’d like to seize neurophysiologic mechanisms of both motor and mental recovery of TBI patients with ST-based voluntary postural training. In view of the aforesaid, we set series of problem:

1) To compare ST and EEG features in primary motor deficit and primary mental impairment after severe TBI (Post-traumatic KS).

2) To analyse the peculiarities of restoration of motor and mental functions when voluntary postural training with ST is a considerable part of rehabilitation program.

3) To study main features of EEG reorganization in voluntary postural control in healthy volunteers. This part is available for understanding neurophysiologic mechanisms charged with rehabilitation effect of ST.

Jointly using of clinical-rehabilitation scales, stabilographic and EEG analysis before rehabilitation course current study has revealed some specific impairment in TBI patients with predominant motor or higher mental deficits. The rate of CPO fluctuations (stabilography) was higher in patients with primary motor deficit, thus reflecting their harder costs to maintain balance in compare with KS patients. These results are supported by previous findings of increased CPO values in patients surviving brain damage, and minimal CPO values in professional athletes [30,31]. On the other hand, stabilographic tasks requiring body displacement in three-dimensional space presented maximal problems for KS patients with minimal movement deficit. So, analysis of performance quality of stabilographic tasks experimentally confirmed space perception disorders found out in KS by previous clinic studies [7].

Our EEG data showed the lower coherence values in TBI patients than normal as reflection of coupling suffer especially between distant cortical areas in both patients’ groups before rehabilitation. There are some EEG findings related to damage cortical connectivity as a result of sport injury [32]. On the other hand, DTI data being a promising tool to detect axonal injury demonstrated a primary damage of long cortical-cortical and corticalsubcortical axonal ways especially of corpus callosum in TBI patients [8-10]. These data confirm the idea of conduction pathways damage being one of major consequences of brain injury that goes with disintegration (uncoupling) of functionally significant brain regions, and

after all with disabilities [8-10].

Furthermore we described peculiarities of EEG coherence changes in groups of patients with predominant motor or higher mental deficits. The lowest EEG coherence values were at the central and parietal cortical areas (zones of motor and postural presentation); it was a specific feature of patients with mainly motor deficit. While in KS patients EEG coherence was minimal between left frontal and right occipital-parietal cortical areas along so-called “cognitive axis”, going with disability to make appropriate spatial assessments, to switch attention from one type of activity to another, and to place events and actions on the time scale [27,28].

A comparison of the integrated parameters in TBI patients before and after courses of rehabilitation including voluntary postural training with visual feedback demonstrates recovery of motor (postural) as well as mental functions after rehabilitation. Some explorers found the similar results in brain-injured patients during rehabilitation course with ST [21-23,30,31]. At the same time, there is a problem of the direct role of ST as compared with other rehabilitation procedures after TBI and also with spontaneous recovery processes that can proceed for a long time after trauma. However some previous research showed that rehabilitation with ST gave a higher gain in recovery of patients with different form of brain pathology than programs without ST [24].

We proposed that positive effect of rehabilitation with postural training supports Luria’s hypothesis as motor training might serve a trigger of recovery both motor as well as higher mental functions [28]. Yet a patient faced immediately with results of postural task performance due to visual feedback attracting his attention and switching on his motivation.

It seems important that EEG coherence increased maximally after RC-ST in interhemispheric pairs with the highest values in central and parietal areas for different spectral bands. Taking into account genesis of EEG rhythms these data may reflect functional integration between different cortical and subcortical structures for provision of the postural control during this rehabilitation approach [33,34]. Data obtained in recent years using DTI directly confirm this EEG finding. So, EEG and DTI data allow supposing that functional integration emerges both due to new pathways’ formation and to recruitment of previously unused surviving structures and connections as a result of specific rehabilitation arrangement.

New data of mammals’ experi­ment have appeared recent years supporting the important role of motor training in neurogenesis. Particularly it should be noted the following: animal experiments have shown this process is more apparent in individuals with active seeking behavior combined with elevated motor activity [35]. Recent neuroimaging studies in TBI patients demonstrated fundamental potentialities of new axonal pathways forming associated with successful rehabilitation outcome [11]. On the whole the results of these studies are optimistic in terms of new neurorehabilitation approaches for patients surviving severe brain injury.

Successful outcome of rehabilitation with postural training may be explained by an important biological role in supporting vital functions during the formation of a human’s ability to stand upright during evolution. Comparison of EEG coherence increase for different spectral bands in healthy persons when standing up and performing of postural tasks with data of the EEG rhythm generation support the concept of dynamic interaction between the hierarchically organized brain structures, both cortical and subcortical [34,35]. In regard to our data EEG coherence was increased predominantly in right hemisphere in standing and postural task performance. It is known that morpho-functional properties of human brain are asymmetric with larger volume of white matter and density of axonal fibers in right hemisphere [36]. Besides, clinical and EEG studies showed the tighter functional connections of the right hemisphere with the vitally important diencephalon structures than of the left one. Numerous neurorehabilitation approaches are based on procedures promoting primary activation of right hemisphere: emotionally significant stimuli, music therapy, aromatherapy, etc. [37,38]. It may to mean particular important role of right hemisphere activation in recovery process after TBI.

At last, increase of EEG coherence at the frontal cortical areas during performance of voluntary postural tasks support the notion of the dynamic interaction between the hierarchically organized brain structures with the leading role of the brain’s cortex in executive functions [39].

Integral clinical, stabilographic, and EEG approach is an informative tool for estimation of different functional disorders in TBI patients before and after rehabilitation course. Specific alterations of stabilographic and EEG parameters may be markers of primary motor or higher mental deficit observed in different terms after TBI. EEG parameters may provide evidence of activating cortical and subcortical integration (interaction), mainly in right hemisphere during standing position and performance of postural tasks. We propose that rehabilitation approach including voluntary postural training with visual feedback serves as a trigger and an integrator in the recovery of impaired motor and higher mental function in TBI patients.