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Abstract More than 100 years of research have passed by and still the human electroencephalogram (EEG) remains a puzzle to be solved. Starting from his studies on plethysmography until his theories on brain thermodynamics, Hans Berger was able to refine his method of recording cortical signs with the apparatus at his disposal in an ordinary neuropsychiatric yard towards an early account of human EEG. This review is an appraisal of his contribution to the field of modern neurophysiology.
Resumo Mais de 100 anos se passaram e o eletroencefalograma humano (EEG) continua sendo um enigma a ser desvendado. A partir de seus estudos sobre pletismografia até suas teorias sobre termodinâmica cerebral, Hans Berger conseguiu refinar seu método de registro da atividade elétrica cortical com os equipamentos a sua disposição em uma ala psiquiátrica comum produzindo uma descrição acurada do EEG humano. Esta revisão é um breve resumo de sua contribuição para o campo da neurofisiologia moderna.
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Abstract Introduction: This study aims to evaluate late postoperative neurophysiological outcomes in patients after coronary artery bypass grafting (CABG). Methods: Forty-five male patients with stable coronary artery disease aged 45-69 years underwent extended neuropsychological assessment using the software Status PF and electroencephalographical examination 3-5 days before CABG and 5-7 years after CABG. Postoperative decline in cognitive functions was determined by a 20% decrease in the cognitive indicator compared to that at baseline on 20% of the tests included in the Status PF battery. Statistical analysis was performed using the software STATISTICA 10.0. Multiple regression was used to identify demographic, clinical, and electroencephalographical variables associated with adverse cognitive outcomes. Results: Cognitive decline was observed in 54% of the patients in the long-term postoperative period. Five to seven years after CABG, all patients have shown an increase in the theta rhythm power compared to the preoperative values, which is most pronounced in the frontal and temporal areas of the right hemisphere (P=0.04), along with a decrease in the alpha rhythm in the posterior areas of the cortex (P=0.005). Multiple regression has reported that the main predictors of cognitive impairment are slower mean alpha frequency, decreased theta-2 rhythm with eyes closed in the right temporal area, and increased theta-2 rhythm with eyes open in the left temporal area (F(5.39)=8.81; P<0.00007; adjusted R-squared=0.57). Conclusion: Our findings indicate that 54% of the patients suffer from postoperative cognitive decline associated with increased theta and decreased alpha rhythms 5-7 years after CABG.
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Coronary Artery Disease/surgery , Cognition Disorders/etiology , Cognitive Dysfunction , Postoperative Complications/etiology , Coronary Artery Bypass , Neuropsychological TestsABSTRACT
Introdução: a meditação é uma técnica ancestral praticada por tradições religiosas e não religiosas, para alcançar benefícios espirituais e na saúde. É considerada um dos estados alterados de consciência. Estudos com ressonância magnética funcional e eletroencefalografia revelaram que existe diminuição da atividade cerebral no lóbulo parietal superior, durante a meditação. Na meditação, a frequência alfa aumenta no córtex cerebral quando comparada ao relaxamento e é caracterizada por ondas rítmicas associadas ao relaxamento e à diminuição de processo cognitivo. Objetivo: descrever e comparar a distribuição de potência da frequência cerebral alfa, nos estágios de MD e RL, nas regiões cerebrais frontal, central e occipital e, comparar as diferenças entre as regiões, de meditadores experientes da casa Brahma Kumaris, praticantes da meditação Raja Yoga, de Salvador BA-Brasil. Metodologia: participaram 14 voluntários neste experimento. A coleta de dados foi realizada com EEG (21 eletrodos). O protocolo utilizado envolveu 6 minutos de relaxamento e 12 minutos de meditação. Os voluntários precisavam ter tido uma noite de sono adaptada à sua rotina e não terem ingerido bebidas estimulantes antes da coleta de dados. Resultados: encontrou-se aumento da densidade alfa na região occipital, na meditação para a média (µV2 / Hz), quando comparada às regiões frontal e central. Obteve-se um tamanho de efeito médio para alfa em relação às comparações entre as regiões frontal e central e um tamanho de efeito pequeno para alfa, entre as regiões central e occipital, durante o processo meditativo. Para as outras regiões, nenhum tamanho de efeito significativo para alfa foi encontrado. Conclusão: não foram encontradas diferenças significativas para alfa, entre os estados de meditação e relaxamento, porém a densidade de potência alfa foi maior na região occipital, quando comparada com as regiões frontal e central; entretanto, essa diferença não apresentou um tamanho de efeito do d de Cohen de relevante magnitude.
Introduction: meditation is an ancient technique practiced by religious and non-religious traditions to achieve spiritual and health benefits. It is considered one of the altered states of consciousness and studies with fMRI and EEG revealed that there is decreased brain activity in the upper parietal lobe during meditation. In meditation, alpha frequency increases in the cerebral cortex when compared to relaxation and is characterized by rhythmic waves associated with relaxation and decreased cognitive process. Objective: to describe and compare the EEG alpha power density distribution during the stages of meditation and relaxation in the frontal, central and occipital regions of experienced Brahma Kumaris Rajayoga meditators. Methodology: volunteers in number of 14 participated in this experiment. Data collection was performed with EEG (21 electrodes). The protocol used involved six minutes of relaxation and 12 minutes of meditation. Volunteers needed to have had a night's sleep suited to their routine and had not inhaled stimulant drinks prior to data collection. Results: we found an increase in alpha density in the occipital region in meditation for the general mean (µV2 / Hz), when compared to the frontal and central regions. A mean effect size for alpha was obtained relative to the comparisons between the frontal and central regions and a small effect size for alpha between the central and occipital regions during meditative process. For the other regions, no significant effect size for alpha was found. Conclusion: no significant differences were found for alpha between the states of meditation and relaxation, but the alpha potency density was higher in the occipital region, when compared with the frontal and central regions; however, this difference did not present a Cohen's d effect size of relevant magnitude
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MeditationABSTRACT
BACKGROUND: One of the key issues in electroencephalogram (EEG) monitoring is accurate signal acquisition with less cumbersome electrodes. In this study, the L2 phase electro-deposited nanoporous platinum (L2-ePt) electrode is introduced, which is a new type of electrode that utilizes a stable nanoporous platinum surface to reduce the skin-electrode impedance. METHODS: L2-ePt electrodes were fabricated using electro-deposition technique. Then, the effect of the nanoporous surface on the surface roughness and the electrode impedance were observed from the L2-ePt electrodes and the flat platinum (FlatPt) electrode. The skin-electrode impedances of the L2-ePt electrodes, a gold cup electrode, and the FlatPt electrode were evaluated when placed on the hairy occipital area of the head in ten subjects. For the validation of using the L2-ePt electrode, a correlational analysis of the alpha rhythms was performed in the same subjects for simultaneous EEG recordings using the L2-ePt and clinically-used EEG electrodes. RESULTS: The results indicated that the L2-ePt electrode with a roughness factor of 200 had the lowest mean impedance performance. Moreover, the proposed L2-ePt electrode showed a significantly lower mean skin-electrode impedance than the FlatPt electrode. Finally, the EEG signal quality recorded by the L2-ePt electrode (r = 0.94) was comparable to that of the clinically-used gold cup electrode. CONCLUSION: Based on these results, the proposed L2-ePt electrode is suitable for use in various high-quality EEG applications.
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Alpha Rhythm , Electric Impedance , Electrodes , Electroencephalography , Head , PlatinumABSTRACT
0.05).(2) The entropy value of the ADHD with ODD group was significantly higher than that of the normal controls in the right frontal region,right central region,and bilateral occipital region(P
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Objective:To investigate methylphenidate response to different subtypes of attention deficit hyperactivity disorder(ADHD) boys by measuring the changes of the alpha competitive structure after administration of single dose of methylphenidate,explore the neuropathological mechanism and search for the sensitive index to predict methylphenidate response in this disorder.Methods:The study involved 88 ADHD boys(40 ADHD-C boys,48 ADHD-I boys) who met the DSM-Ⅳ diagnostic criteria of ADHD,and their continuous Electroencephalogram(EEG) data collected before and 2 hours after taking methylphenidate(10 mg) were analyzed with EEG-encephaloflutuographic technology(EEG-ET).Results:After taking methylphenidate,(1) The main frequency of alpha band obviously increased in ADHD-C boys and ADHD-I boys(from 9.05?0.96 Hz up to 9.72?0.99 Hz,P=0.000;from 8.90?0.93 Hz up to 9.25?0.86 Hz,P=0.002;separately),especially in ADHD-C boy group(Z=-2.111,P=0.035).(2) The dominant probability of 8 Hz was significantly decreased in ADHD-C boys and ADHD-I boys(from 24.34%?12.70% down to 20.74%?12.46%,P=0.002;from 28.82%?12.51% down to 25.64%?12.176%,P=0.003;separately).There was no significant difference in the changes of the dominant probability of 8 Hz between the two ADHD groups(Z=-0.494,P= 0.621).(3)The entropy value was significantly decreased in ADHD-I boys group(from 0.74?0.10 down to 0.70?0.13,t =3.579,P=0.001).There was no significant difference in the changes of the entropy value between the two ADHD groups(Z=-1.131 P= 0.258).Conclusion:After administra-tion of single dose of methylphenidate,slow ? wave decreased in ADHD boys,especially in ADHD-Cboy group;Single dose of methylphenidate can ameliorate the brain self-organization of ADHD-I boys.These findings suggest that the main frequency of alpha band may be the sensitive index to predict methylphenidate response in ADHD.
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Objective:To explore the alpha competitive structure in children with attention deficit hyperactivity disorder(ADHD)with/without learning disabilities(LD).Methods:According to DSM-Ⅳ diagnostic criteria,the study involved ADHD children with LD,pure ADHD children and normal controls.Each group consisted of 68 subjects.All subjects were between the ages of 7 and 14 years,and the groups were matched by sex,age and ADHD subtypes.EEG data were recorded during an eye-closed resting period and then were analyzed with EEG-encephaloflutuographic technology(EEG-ET).Results:(1)The pure ADHD children showed significantly more 8 Hz activity(25.84%?14.81%)than that of the normal control group(16.50%?11.42%,P=0.000);The main frequency of alpha band was 10 Hz in the pure ADHD children,while the energy distribution among alpha components was diffuse.(2)ADHD children with LD showed significantly more 8 Hz and 13 Hz activity(25.11%?11.88%,1.14%?1.14%,separately)than that of the normal control(16.50%?11.42%,0.74%?0.97%,P=0.000,P=0.009,separately);The dominant probability of 10 Hz(27.80%?13.28%)in this group was significantly lower than that of the control group(36.06%?17.21%,P=0.011);The energy distribution among alpha components was diffuse in ADHD children with LD,whose main frequency of alpha band was 9 Hz;The entropy value of the ADHD children with LD was significantly higher than that of the control group in the right brain and the left parietal region,temporal region,occipital region(P
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Objective:To investigate the effects of stimulant medications on the EEG of children with attention deficit hyperactivity disorder(ADHD) by measuring the changes of the alpha competitive structure after administration of single dose of methylphenidate,and to explore the neuropathological mechanism of ADHD.Methods:The study involved 110 ADHD children who met the DSM-Ⅳ diagnostic criteria of ADHD and 110 normal children matched by age and sex.Their continuous EEG data were collected before and 2 hours after taking methylphenidate(10 mg) and were analyzed with EEG-encephaloflutuographic technology(EEG-ET).Results:(1)After taking methylphenidate,the main frequency of alpha band obviously increased [(8.97?0.94) Hz vs.(9.40?0.99) Hz,P0.05].Conclusion:Single dose methylphenidate can ameliorate the brain self-organization in ADHD children and improve the lower efficient state,and produce changes in the EEG towards normalization.
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Objective To study the characteristics of EEG after tramsient ischemic attack and to offer reference for screening procedure of aircrew and astronaut selection. Method The dominant frequency uncertainty of alpha band EEG in 12 pilots(males; age 30±5) with transient ischemic episodes in middle cerebral artery(MCA) territories and in 20 normal healthy pilots was analyzed with frequency-fluctuation analysis. Result The dominant probability of the main frequency coinciding with sites affected by transient ischaemic attack(TIA) in patient pilots was higher than that in healthy pilots (P<0.01),and the dominant probability ratio logarithmic index I≥0 in all patient pilots with normal EEG, but I<0 in all healthy pilots. It was also found that not only I≥0, but the second component shifted to lower frequency(8 Hz) in patients with slight focal EEG alterations,i.e. slowing of frequency. The relative entropy values (percentage) were decreased significantly in pilots with TIA as compared with healthy pilots (P＜0.05). Conclusion The dominant frequency uncertainty analysis of alpha band showed clear superiority of computerized evaluation over routine visual assessment for the diagnosis of minor cerebral ischemia. It offers not only a possibility of studying pathophysiological functional parameter, but also the reference for screening procedure in aircrew and astronaut selection.