Specific EEG frequencies signal general common cognitive processes as well as specific task processes in man

Harmony, Thalı́a; Fernández, Thalı́a; Gersenowies, Jorge; Galán, Lı́dice; Fernández-Bouzas, Antonio; Aubert, Eduardo Henrik; Dı́az-Comas, Lourdes

doi:10.1016/j.ijpsycho.2004.04.006

Cited by 34 publications

(20 citation statements)

References 35 publications

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“…Delta results are in line with most calculation task studies, which have mainly used EEG and analyzed power distributions (Harmony et al 1996(Harmony et al , 2004Dimitriadis et al 2010;Giannitrapani 1971). Delta band activity is considered to increase during cognitive tasks requiring attention to internal processing and to decrease under conditions which demand attention to the external environment.…”

Section: Resting Vs Idics Tasksupporting

confidence: 72%

Synchronization during an internally directed cognitive state in healthy aging and mild cognitive impairment: a MEG study

López

Garcés

Cuesta

et al. 2014

AGE

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Mild cognitive impairment (MCI) is a stage between healthy aging and dementia. It is known that in this condition the connectivity patterns are altered in the resting state and during cognitive tasks, where an extra effort seems to be necessary to overcome cognitive decline. We aimed to determine the functional connectivity AGE (2014) pattern required to deal with an internally directed cognitive state (IDICS) in healthy aging and MCI. This task differs from the most commonly employed ones in neurophysiology, since inhibition from external stimuli is needed, allowing the study of this control mechanism. To this end, magnetoencephalographic (MEG) signals were acquired from 32 healthy individuals and 38 MCI patients, both in resting state and while performing a subtraction task of two levels of difficulty. Functional connectivity was assessed with phase locking value (PLV) in five frequency bands. Compared to controls, MCIs showed higher PLV values in delta, theta, and gamma bands and an opposite pattern in alpha, beta, and gamma bands in resting state. These changes were associated with poorer neuropsychological performance. During the task, this group exhibited a hypersynchronization in delta, theta, beta, and gamma bands, which was also related to a lower cognitive performance, suggesting an abnormal functioning in this group. Contrary to controls, MCIs presented a lack of synchronization in the alpha band which may denote an inhibition deficit. Additionally, the magnitude of connectivity changes rose with the task difficulty in controls but not in MCIs, in line with the compensation-related utilization of neural circuits hypothesis (CRUNCH) model.

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Section: Resting Vs Idics Tasksupporting

confidence: 72%

Synchronization during an internally directed cognitive state in healthy aging and mild cognitive impairment: a MEG study

López

Garcés

Cuesta

et al. 2014

AGE

View full text Add to dashboard Cite

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“…Frequency Domain VARETA has previously been used by our group to evaluate the topography of brain lesions , as well as to study cognitive processes (Fernández et al 1998Harmony et al 1999Harmony et al , 2001Harmony et al , 2004). …”

Section: Interview Of Parentsmentioning

confidence: 99%

Changes in EEG Current Sources Induced by Neurofeedback in Learning Disabled Children. An Exploratory Study

Fernández

Harmony

Fernández-Bouzas

et al. 2007

Appl Psychophysiol Biofeedback

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The objective of this work was to explore Neurofeedback (NFB) effects on EEG current sources in Learning Disabled (LD) children, and to corroborate its beneficial consequences on behavioral and cognitive performance. NFB was given in twenty 30-min sessions to 11 LD children to reduce their abnormally high theta/alpha ratios (Experimental Group). Another five LD children with the same characteristics received a placebo treatment (Control Group). In the Control Group no changes in behavior or EEG current source were observed. In the Experimental Group, immediately after treatment children showed behavioral and cognitive improvements, but current source analysis showed few modifications; however, 2 months after treatment many changes occurred: a decrease in current of frequencies within the theta band, mainly in left frontal and cingulate regions, and enhancement in current of frequencies within the alpha band, principally in the right temporal lobe and right frontal regions, and of frequencies within the beta band, mainly in left temporal, right frontal and cingulate cortex regions. In conclusion, NFB is a possibly efficacious treatment for LD children with an abnormally high theta/alpha ratio in any lead. The changes observed in EEG current sources may reflect the neurophysiological bases of the improvement that children experienced in their behavioral and cognitive activities.

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“…Alzheimer's disease (AD) is an age-related progressive, neurodegenerative disorder that is characterized by loss of memory and cognitive decline [1,2] and it is the main cause of disability among older people [3]. AD is ranked as the sixth leading cause of death in US [4].…”

Section: Introductionmentioning

confidence: 99%

Complexity Measures for Quantifying Changes in Electroencephalogram in Alzheimer’s Disease

et al. 2018

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Alzheimer's disease (AD) is a progressive disorder that affects cognitive brain functions and starts many years before its clinical manifestations. A biomarker that provides a quantitative measure of changes in the brain due to AD in the early stages would be useful for early diagnosis of AD, but this would involve dealing with large numbers of people because up to 50% of dementia sufferers do not receive formal diagnosis. Thus, there is a need for accurate, low-cost, and easy to use biomarkers that could be used to detect AD in its early stages. Potentially, electroencephalogram (EEG) based biomarkers can play a vital role in early diagnosis of AD as they can fulfill these needs. This is a cross-sectional study that aims to demonstrate the usefulness of EEG complexity measures in early AD diagnosis. We have focused on the three complexity methods which have shown the greatest promise in the detection of AD, Tsallis entropy (TsEn), Higuchi Fractal Dimension (HFD), and Lempel-Ziv complexity (LZC) methods. Unlike previous approaches, in this study, the complexity measures are derived from EEG frequency bands (instead of the entire EEG) as EEG activities have significant association with AD and this has led to enhanced performance. The results show that AD patients have significantly lower TsEn, HFD, and LZC values for specific EEG frequency bands and for specific EEG channels and that this information can be used to detect AD with a sensitivity and specificity of more than 90%.

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Specific EEG frequencies signal general common cognitive processes as well as specific task processes in man

Cited by 34 publications

References 35 publications

Synchronization during an internally directed cognitive state in healthy aging and mild cognitive impairment: a MEG study

Synchronization during an internally directed cognitive state in healthy aging and mild cognitive impairment: a MEG study

Changes in EEG Current Sources Induced by Neurofeedback in Learning Disabled Children. An Exploratory Study

Complexity Measures for Quantifying Changes in Electroencephalogram in Alzheimer’s Disease

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