Please use this identifier to cite or link to this item: http://localhost:8081/xmlui/handle/123456789/13987
Authors: H, Nagendra
Keywords: Cognition refers;non-invasive;human electroencephalogram;decision making
Issue Date: Jan-2016
Abstract: Cognition refers to the processes an individual uses to reorganize information and targeted at enhancing physical and mental capabilities through conventional or non-conventional methods. The cognitive abilities include attention, perception, concentration, memory, processing speed, decision making, and reasoning. Cognitive enhancement aims at the improvement of these core cognitive functions through interventions. The interventions can be non-conventional or conventional. Specific neurological changes can be achieved through either of these interventions. The use of non-conventional methods are generally invasive in nature and raise many safety and ethical issues; while the conventional methods are inherently non-invasive and they are widely accepted by the society. In this study three conventional methods, action video gaming, yoga, and physical exercises are used as intervention to evaluate the cognitive behaviour among three different groups of populations. In the first study, the positive impact of action video game on congenitally deaf and dumb subjects is investigated. In the second study, the effect of yoga practice on cognitive skills, autonomic nervous system, and heart rate variability are analyzed among healthy Engineering subjects. In the third study, the impact of physical exercise and range firing training on cognitive functions and heart rate variability (HRV) are investigated among newly recruited young and healthy Indian Jawans. The human electroencephalogram (EEG) reflects nervous system activity and is an important tool in the investigation of cognitive functions. The HRV derived from ECG signal indicate the neural regulation of the heart and is representative of the variations of several physiological activities. Thus the physiological parameters particularly EEG and ECG are better representative of the cognitive functions and mental health. In this study both EEG and ECG signals were simultaneously recorded with 500 samples/seconds. Study 1: Video game as intervention. In this study the Counter Strike which is the first Person Shooter Game was chosen to investigate the impact of cognitive functions among the deaf and dumb subjects. This game involves fast paced activity, making quick decision, and rapid hand eye coordination. Thirty deaf and dumb subjects (age=15.90±2.67) from school of Anusruti, formerly known as school for deaf and dumb participated in this study. Experimental group (Game Players) played First Person Shooter video game for 96 hours. The IQ levels of the subjects were evaluated using a Draw-A-Man Test and mean reaction time determined using simple stroop color word test. The IQ levels were scored from the draw a man test drawings of subjects using standard procedures by the experts. Subjects with high HRV performed faster with lesser number of mean errors than the low HRV subjects in stroop color word test. At the end of intervention period the mean reaction time was improved by 9.75%. The improvement in the mRTs means the improvement in certain cognitive performances; such as hand-eye co ordination, attention, working memory, ii decision making, and higher processing speed. These in turn indicate the better functioning of the brain. Certain cognitive functions such as memory or alertness (β/θ=21.05%), attention resource index (β/(α+θ)=27%), and executive functions ((δ+θ)/α=38.9%) were found improved among experimental group. The β band power increased in central (10.81%), parietal (21.29%) and occipital 61.73%) lobes where as α band power increased in occipital (8.32%) and temporal (3.71%) lobes. As the parietal and occipital lobes are associated with processing of sensory and visual signals, the increase of α and β band powers indicate the enhancement of these cognitive functions. The increase of α also indicate the improvement of attention, memory, and mean reaction time. On other hand the increase of β band power indicate the improvements in visual perceptions, hand eye coordination and other cognitive functions. The increase of band powers in parietal, occipital and temporal lobes indicate the improved visual and planning skills. The θ band power increased (13.95%) in parietal lobes, while γ band power in central (40.55%) and parietal 14.72%) lobes. The increase of θ reflects enhancement of certain cognitive performances such as visual perception, attention, memory, and motor skills. The α/β (106.54%) ratio which is indicator of arousal state of the person increased in frontal lobe, indicating enhancement in the reasoning and mental abilities. The central nervous system arousal index (θ/β) was decreased by 5.77%. The high HRV subjects who demonstrated significant improvements in mRTs had also higher level of IQs and displayed significant improvements on visual tasks. The results indicate that playing action video games can greatly enhance certain cognitive functions among deaf and dumb subjects; however there is significant reduction in the heart rate variability (5.88%), which may have negative impact on health. The ratio of SDNN/RMSSD was reduced by 12.89% and its surrogate LF/HF ratio was decreased by 72.48%. Also the ratio (δ+θ)/(α+β) was decreased by 46.55%. The index of well being (α/θ ) was decreased by 4.82% and the heart rate index (The index of well being (θ/α)) was decreased by 1.41%. These further substantiate the negative impact of video gaming among the players. Study 2: Yoga as intervention. Yoga is an ancient method and its growing research evidence supports its practice can provide both psychological and physiological benefits; and can enhance certain cognitive performances. In this study 30 young healthy engineering subjects (age=22.42±2.30) participated. The experimental group was provided same yoga training for a period of 4months for 1.5 hours per day between 6p.m to 7.30p.m except Sundays and holidays. The regular practices of yoga for a period of four months resulted improvement of certain cognitive functions, in addition to improvement in heart rate variability. The subjects practiced simple physical exercises, pranayamas, mediation, and surynamaskar. The β band power increased (29.21%) indicating improvement in memory; α band power which is indicator of mean reaction times was enhanced by 43.54%, and δ band iii power improved by 37.21% indicating improvement in attention and concentration. The overall cognitive performance (θ/β) was increased by 64.83%. The executive load index ((δ+θ)/α=69.42%) was found decreased indicating activation of specific cortical network of the brain. The performance level ((δ+θ)/(α+β)=103.41%), engagement index ((β/(α+θ)=147.82%), memory were found enhanced. The mHRV increased by 7.41%, while the ratio SDNN/RMSSD which is surrogate of LF/HF was increased by 44.16%, while LF/HF decreased by 71.41% indicating improved nervous system activity. These indicate improvement in the heart rate variability and enhanced sense of wellbeing. Yoga group showed significant improvement (7.41%) in the HRV compared to baseline values. The global β activity was increased by 111.46%, α activity by 43.57%, δ activity by 37.36%. The central nervous system activity was decreased by 50%, attention resource index β/(α+θ) increased by 147.83%, and executive load index (δ+θ)/α was decreased by 40.98%. The heart rate index θ/α decreased by 48.24% and α/θ was increased by 93.11%. The results suggest that the practice of yoga modifies the sympathovagal balance towards parasympathetic activation. Therefore regular practice of yoga can result in improvements of physiological parameters, indirectly improving psychological parameters and certain cognitive functions. Study 3: Physical exercise and range firing as intervention. Physical exercise is an activity that is planned, structured, and purposive to improve specific physical and cognitive skills. In contemporary military strategies apart from physical strengths, cognitive aptness has become a necessary requirement to accomplish mission critical tasks. The enhancement of army personnel performance should, therefore discuss both body and brain. In this study thirty one subjects randomly selected from newly recruited Indian Army Jawans. All the subjects were in the age group of 18-22 years. Each participant took a same level of training session for a period of four months, which included physical exercises, drill, games, Tae Kwon(smashing and jumping), and rifle weapon firing. Physical exercise and range firing training intervention resulted significant improvement in mean heart rate variability (5.98%).The improved HRV reflect range of adaptability, better functioning of cardiovascular system and enhanced functioning of the brain. The global EEG band powers of β(36.48%), α(19.45%), δ(13.56%), γ(21.46%) were increased while θ band power decreased (4.85%). The increase of β power indicates improvement in mRTs, visual information processing capacity, and higher level of alertness; the increase of α activity is an indicator of improved memory, and other brain functions. The increase of δ, and γ band powers indicate synchronization of brain activity, autonomous nervous system activity, and high level information processing capacity. The engagement index (β/(α+θ)) which measures how a person is engaged in tasks is increased by 35.71%; while the arousal index(β/α) an indicator of concentration is increased by 14.5%. The iv improvements of these parameters reflect improvement in certain cognitive functions such as attention, vigilance, and motor action and balanced ANS activity. The neural activity (β/θ) enhanced by 43.91% while the central nervous system activity index (θ/β) was decreased by 30.27%. The heart rate index (θ/α) decreased by 20.36% while the performance index or index of well being (α/θ) was increased by 25.54%. The ratio of sum of low frequency to sum of high frequencies (δ+θ)/(α+β) which is equivalent to the ratio of LF/HF ratio of heart rate variability was lowered by 71.41%. The heart rate was decreased by 5.29% while the time domain ratio SDNN/RMSSD was increased by 7.14% and its surrogate in frequency domain LF/HF ratio was increased by 6.63%. The increase of the ratio LF/HF ratio may due to the decreased parasympathetic activity. These indicate the dominance of sympathetic activity due to anxiety or the stress experienced by the subjects during training intervention. In a nutshell, it can be verbalized that, with video game intervention except θ band power the other four frequency band powers have been increased indicating the positive impact of action video gaming on certain cognitive functions among the players. However the mean heart rate variability was decreased indicating negative impact on the health. On other hand the yoga intervention produced the increased α, β and δ powers while reduction in θ and γ band powers. The increased values of these band powers are associated with improvement in specific cognitive abilities among the subjects. Also the mean heart rate variability was improved indicating the more balanced autonomous nervous system activity. Similarly, the exercise intervention resulted in the increase of α, β, δ and γ band powers while reducing the θ activity. The increases of these band powers are also associated with improvements of particular cognitive functions. It also resulted improvement in heart rate variability. Thus a well designed experiment can enhances specific cognitive abilities, improved health and increased sense of well being. These interventions can also be used in the educational context, and for rehabilitation purposes.
Research Supervisor/ Guide: Kumar, Vinod
Mukherjee. S.
metadata.dc.type: Thesis
Appears in Collections:DOCTORAL THESES (Electrical Engg)

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