**Author details**

in EEG acquisition due to electrodes placement, skull muscle movement, environment noises, limitations in hardware, and their calibrations. Two or more tasks need to be performed simultaneously in hybrid that might increase mental workload and cause discomfort to some users. Due to complexity, prior knowledge is required to use hybrid systems for target users. This demands for further research and hybrid BCI is still under development

Hybrid BCI has wider future scope and combining three or more signals may result better performances. Optimum combination of signals with high degree of compatibility may be obtained which is accessible to all [98]. Virtual environment-controlled applications [72] may turn to a real one which may provide easy access to target as well as healthy users. These applications may be broadened to people without disabilities too. Various researches are going on to calculate mental workload of armed soldiers, and brain automation control of wheelchair may be extended to control automobiles and airplanes [99]. Efficient algorithms need to be developed in future to make BCI practical with high accuracy and speed which act as a neurorehabilitation for stroke patients suffering from movement and language deficits. Human's intentions, emotions, and behaviors might be predicted in future using EEG which will ease for identifying fatigue in soldiers during war. It might be used in children to study various psychological measures such as behavior and learning tendency relative to age, and can be extended to animals besides human [97]. The laboratory experiment may be extended to the real world to ease our daily lives. Eventually, these might attract stakeholders to invest

Brain is a self-sustained oscillator where individual neurons oscillate at certain harmonics. Major rhythms of motor outputs generate through bifurcation. Several linear (spectral coherence and cross-correlation) and nonlinear (phase synchronization, mutual information and entropy) measures have been adopted to measure the oscillations [100]. Structural and functional connectivity of the brain works in coherence to perform a common action. Structural connectivity relates to the physical connection between different regions of the brain, while functional connectivity is the correlation between various regions over time that shows

During cognitive tasks requiring attention, certain brain regions become more active while the other regions activity decreases. A flashing or flickering visual stimulus eliciting event or evoked potential (P300 or SSVEP) increases activity in frontal and visual cortex. Due to more repetitive mental tasks, brain activity increases in the specific region, whereas activity in the other regions is reduced. The reason for reduction may be due to unrelated or difficult tasks [102]. This increase in brain activity corroborates growth in working memory of brain illustrating brain dynamic states. Brain changes its state according to the environment similar

in BCI industry to produce commercialized BCI products in future.

**8. Discussion and conclusion**

dynamic behavior [101].

inside laboratory [57, 70].

130 Evolving BCI Therapy - Engaging Brain State Dynamics

**7. Future scopes**

Bijay Guragain, Ali Haider and Reza Fazel-Rezai\*

\*Address all correspondence to: reza.fazelrezai@engr.und.edu

Biomedical Signal and Image Processing Laboratory, University of North Dakota, USA
