Estudo da coerência do eletrencefalograma para a banda de frequência alfa em indivíduos adultos normais e com provável demência do tipo Alzheimer

Anghinah, Renato; Kanda, Paulo Afonso Medeiros; Jorge, Mário Silva; Lima, Edson Erasmo Pereira; Pascuzzi, Luiz; Melo, Antonio Carlos de Paiva

doi:10.1590/s0004-282x2000000200011

Cited by 31 publications

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“…Concerning the inter-hemispheric coherence value found in the present study for each age bracket of the sample, no significant differences were observed between the 20-29 year, 30-39 year, and 40-49 year age groups. For the 20-50 year age group, EEG spectral characteristics tend to change little, in contrast to both younger (under 10 years) and elderly (over 60 years) groups, according to previous studies in our setting [17][18] . Marozi et al 19 , in an evolutive study, found increased coherence in the frontal region across all bands, except beta, in a population of 46 students followed for 3 years.…”

Section: Discussionsupporting

confidence: 80%

Study of interhemispheric coherence on healthy adults

Jorge

Botelho²,

Melo³

2007

Arq. Neuro-Psiquiatr.

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EEG coherence allows correlation between different brain areas to be ascertained by analyzing the mutual relationship between two EEG signals across different frequency bands. As this constitutes a normalized value for the power of a given frequency, it is independent from signal amplitude oscillations 1,2 Such a property makes coherence a relatively safe method for comparing groups of individuals in as far as differences in EEG powers do not impact estimated coherence values 3 . Reduced coherence between two regions is probably indicative of their decreased functional correlations. Ordinary coherence can be calculated between two cerebral electrodes, whether they be placed in the same hemisphere or in homologous areas, by means of a mathematical formula dividing the cross spectrum of these two channels by the product of self spectrum for each of these channels, as illustrated in the formula below:The Co value between two electrodes ranges from 0 to 1, where 1 denotes maximum correlation. When correlation is very low or null, the value approaches 0. Thus, coherence represents a measure of cortical interconnectivity. Studies concerning coherence have shown that coherence between closely-placed electrodes is determined mainly by local connections excited by intracortical interneurons (Martinotti and short axoned stellate cells), whereas between distant electrodes such coherence is determined by long axonal connections 4,5,6 . These two compartments compete with one another, influencing the same neuronal population in an alternate manner.The objective of the current investigation was to study the inter-hemispheric coherence between homologous areas in healthy individuals in the 20-50 year age bracket. METHODA total of 190 tests were carried out on individuals with no neurological complaints, where subjects were submitted to digital EEG and then assessed. Subjects had no prior history of neurological problems such as traumatic brain injury, epilepsy, alcohol or drugs use and abuse, or clinical com- ABSTRACT -The interhemispheric coherence of electroencephalogram was studied in a group of healthy individuals in the age range of 20-50 years. The results showed higher coherence for all bands in parietal regions (P3-P4). It was observed that individuals with high values of coherence for a certain frequency band in a pair of electrodes also showed high values of coherence for other bands across other pairs of electrodes. No significant influence on interhemispheric coherence was found for age, gender or hand dominance. STUDY OF INTERHEMISPHERIC COHERENCE ON HEALTHY ADULTSKEY WORDS: coherence, adults, EEG quantitative, normal pattern. Estudo da coerência interhemisférica em adultos normaisRESUMO -A coerência inter-hemisférica do eletrencefalograma foi estudada em uma população de indiví-duos normais, na faixa etária de 20 a 50 anos. Os resultados mostraram maior valor de coerência para todas as bandas nas regiões parietais(P3-P4). Foi observado que em indivíduos com alto valor de coerência para determinada banda em um det...

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Section: Discussionsupporting

confidence: 80%

Study of interhemispheric coherence on healthy adults

Jorge

Botelho²,

Melo³

2007

Arq. Neuro-Psiquiatr.

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“…In alpha (1-C), main effects of condition [F (2,267) = 7.537; p=0.001], moment [F (2,267) =4.825; p=0.009], and electrode site [F (2,267) =21.345; p=0.000] were found. No interactions were observed.…”

Section: Resultsmentioning

confidence: 99%

“…In this context, the EEG has been widely employed in the assessment of electrophysiological changes induced by distinct medications. Its sensibility in detecting alterations produced by a specific substance may be enhanced by methods of quantitative analyses (qEEG) 2,3 . Quantitative electroencephalography has become, throughout the years, a tool of great clinical utility in evaluating the effects of medications, predicting medication response, and in assessment of cognitive changes produced by such psychoactive substances.…”

Section: Palavras-chave: Bromazepam Eegqmentioning

confidence: 99%

Influence of bromazepam on cortical interhemispheric coherence

Sampaio

Puga

Veiga

et al. 2007

Arq. Neuro-Psiquiatr.

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-Benzodiazepines are among the most commonly prescribed medications due to their therapeutic efficacy in reducing anxiety and inducing sleep. Consequently, they have been widely employed in the pharmacological treatment of several disorders. Nevertheless, few studies have analyzed the effects of bromazepam in electroencephalographic activity (EEG). The present study aimed at investigating the modulatory effects of this drug on brain dynamics. Specifically, the effects of bromazepam (3mg) on EEG coherence were tested in a double-blind experiment. The sample, consisting of 10 healthy subjects (5 male and 5 female), was submitted to ten minutes of EEG recording. The electrophysiological measure (coherence) was analyzed across three experimental conditions: bromazepam, placebo 1, and placebo 2. Results indicate that bromazepam significantly increases cortical interhemispheric coherence.KEY WORDS: bromazepam, qEEG. Influência do bromazepam na coerência cortical inter-hemisféricaRESUMO -Benzodiazepínicos estão entre as medicações mais comumente prescritas devido à sua eficácia terapêutica para reduzir ansiedade e induzir sono. Conseqüentemente, eles têm sido amplamente empregados no tratamento de diversas desordens. No entanto, poucos estudos têm analisado os efeitos do bromazepam na atividade eletrencefalográfica (EEG). Assim, o presente estudo teve por objetivo investigar os efeitos modulatórios desta droga na dinâmica cerebral. Especificamente, os efeitos de 3 mg de bromazepam na coerência eletrocortical foram analisados em um experimento duplo-cego. A amostra consistiu de 10 sujeitos sadios (5 homens e 5 mulheres), submetidos a dez minutos de captação do sinal de EEG. A medida eletrofisiológica (coerência) foi analisada em três condições experimentais: bromazepam, placebo 1 e placebo 2. Os resultados sugerem que o bromazepam aumenta significativamente a coerên-cia cortical inter-hemisférica. PALAVRAS-CHAVE: bromazepam, EEGq.

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“…In this context, electroencephalography (EEG) has been used to monitor the effects of distinct medications on brain dynamics since cortical activity is responsive to the unique characteristics of psychoactive substances (Saletu et al 2002). The EEG sensibility in identifying changes produced by a specific substance may be improved by methods of quantitative analyses (qEEG) (Anghinah et al 2000, Veiga et al 2003. Once drugs have specific effects on wave morphology, changes in qEEG variables can be used to investigate Correspondence to: Isabel Sampaio E-mail: belsampaio@gmail.com mechanisms of drug action as well as to monitor and possibly predict efficacy (Fink 1978).…”

Section: Introductionmentioning

confidence: 99%

The influence of bromazepam on cortical power distribution

Sampaio

Puga

Veiga

et al. 2008

An. Acad. Bras. Ciênc.

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The EEG has been widely employed in the assessment of electrophysiological changes induced by distinct medications. Its sensibility in detecting alterations produced by a specific substance may be enhanced by methods of quantitative analyses (qEEG). The present study aimed at investigating the modulatory effects of bromazepam on brain dynamics. The effects of bromazepam (3mg) on EEG power distribution were tested in 10 healthy individuals, in a double-blind experiment. The electrophysiological measure was analyzed across experimental conditions, moments, and electrodes, in the delta, theta, alpha and beta frequency bands separately. A significant decrease of relative power was observed in delta and theta (main effect of condition). No interactions were observed. Although the expected anxiolytic EEG profile was not observed (increased beta and decreased alpha activity), this specific result may be related to other factors such as dosage used and the subjects' general physiological state, and not necessarily to the drug itself.

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Estudo da coerência do eletrencefalograma para a banda de frequência alfa em indivíduos adultos normais e com provável demência do tipo Alzheimer

Cited by 31 publications

References 18 publications

Study of interhemispheric coherence on healthy adults

Study of interhemispheric coherence on healthy adults

Influence of bromazepam on cortical interhemispheric coherence

The influence of bromazepam on cortical power distribution

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