Erol Basar

Istanbul Kültür University · Brain Dynamics and Cognition Research Center

The present study tested the hypothesis that cortical sources of resting state eyes-closed electroencephalographic (rsEEG) rhythms reveal different abnormalities in cortical neural synchronization in groups of patients with mild cognitive impairment due to Alzheimer's disease (ADMCI) and dementia with Lewy bodies (DLBMCI) as compared to cognitively...

Parkinson’s disease (PD) is a neurodegenerative disease that is characterized by loss of dopaminergic neurons in the substantia nigra. Mild Cognitive impairment (MCI) and dementia may come along with the disease. New indicators are necessary for detecting patients that are likely to develop dementia. Electroencephalogram (EEG) Delta responses are o...

Objective: This study tested the hypothesis that markers of functional cortical source connectivity of resting state eyes-closed electroencephalographic (rsEEG) rhythms may be abnormal in subjects with mild cognitive impairment due to Alzheimer's (ADMCI) and Parkinson's (PDMCI) diseases compared to healthy elderly subjects (Nold). Methods: rsEEG...

Previous evidence showed abnormal posterior sources of resting-state delta (<4 Hz) and alpha (8-12 Hz) rhythms in patients with Alzheimer's disease with dementia (ADD), Parkinson's disease with dementia (PDD), and Lewy body dementia (DLB), as cortical neural synchronization markers in quiet wakefulness. Here, we tested the hypothesis of additional...

The aim of this retrospective and exploratory study was that the cortical sources of resting state eyes-closed electroencephalographic (rsEEG) rhythms might reveal different abnormalities in cortical neural synchronization in groups of patients with mild cognitive impairment due to Alzheimer's disease (ADMCI) and Parkinson's disease (PDMCI) as comp...

Analysis of affective picture processing by means of EEG has invaded the literature. The methodology of event-related EEG coherence is one of the essential methods used to analyze functional connectivity. The aims of the present study are to find out the long range EEG connectivity changes in perception of different affective pictures and analyze g...

The aim of this retrospective exploratory study was that resting state eyes-closed electroencephalographic (rsEEG) rhythms might reflect brain arousal in patients with dementia due to Alzheimer's disease dementia (ADD), Parkinson's disease dementia (PDD), and dementia with Lewy body (DLB). Clinical and rsEEG data of 42 ADD, 42 PDD, 34 DLB, and 40 h...

Background Brain oscillatory responses can be used for non-invasive analyses of cortico-cortical connectivity, local neuronal synchronization, and coherence of oscillations in many neuropsychiatric conditions including Alzheimer's disease (AD). In the present paper, we examine sensory-evoked and event-related gamma coherences elicited by visual sti...

Parkinson’s disease (PD) is a common progressive neurodegenerative disorder. This study aims to compare sensory-evoked oscillations (SEOs) and event-related oscillations (EROs) of visual modality in cognitively normal PD patients and healthy controls. Sixteen PD and 16 age-, gender-, and education-matched healthy controls participated in the study....

The research related to brain oscillations and their connectivity is in a new take-off trend including the applications in neuropsychiatric diseases. What is the best strategy to learn about functional correlation of oscillations? In this report, we emphasize combined application of several analytical methods as power spectra, adaptive filtering o...

The aim of this report is threefold: (1) First, we accomplish a survey integrating the description of consciousness, perception, and memory according to the views of descriptions of Hermann Helmholtz, Sigmund Freud, Henri Bergson, and Gustav Jung. (2) In the second step, we present experimental results for defining the machineries of sensation and...

Objective Decreased delta event-related oscillations (ERO) have been reported in prior studies of Alzheimer’s disease (AD) and mild cognitive impairment (MCI); however no study has examined its utility in predicting disease progression. In this study, we examined the longitudinal changes in brain dynamics of MCI by using delta ERO and volumetric MR...

Objective Parkinson’s disease (PD) is the second most common progressive neurodegenerative disorder which affects both motor and cognitive functioning. This study aims to investigate the sensory evoked oscillations (SEO) and event-related oscillations (ERO) of visual modality in cognitively normal PD patients and healthy controls. Methods Sixteen...

Event-related oscillations (EROs) reflect cognitive brain dynamics, while sensory-evoked oscillations (SEOs) reflect sensory activities. Previous reports from our lab have shown that those with Alzheimer's disease (AD) or mild cognitive impairment (MCI) have decreased activity and/or coherence in delta, theta, alpha and beta cognitive responses. In...

Here we presented a single electroencephalographic (EEG) marker for a neurophysiological assessment of Alzheimer's disease (AD) patients already diagnosed by current guidelines. The ability of the EEG marker to classify 127 AD individuals and 121 matched cognitively intact normal elderly (Nold) individuals was tested. Furthermore, its relationship...

Introduction: The studies on EEG Brain Dynamics of affective picture processing are rapidly increasing. The methodology of event related EEG coherence is one of the essential methods used to analyze functional connectivity. In this study the long distance connectivity between different electrode pairs during affective picture viewing was analyzed b...

Since the beginning of the last century, the localization of brain function has been represented by Brodmann areas, or maps that are a result of anatomic organization. They are used in order to provide a global idea of cortical structures for given sensory cognitive functions. In recent decades, the analysis of brain oscillations has gained high im...

The aim of the present study is three fold, as follows: (1) We propose a new framework describing the neurophysiologic functioning and cognitive processing of neural populations, and we extend the neuron doctrine to the physiology of neural assemblies; (2) The extension from neurons to neural populations implies that the brain, with its connectivit...

The research related to brain oscillations and their connectivity is in a new take-off trend including the applications in neuropsychiatric diseases. What is the best strategy to learn about functional correlation of oscillations? In this report, we emphasize combined application of several analytical methods as power spectra, adaptive filtering of...

Amnesic mild cognitive impairment (MCI) represents a risk of developing Alzheimer's disease (AD), but not all MCI subjects progress to dementia of AD type. Magnetic resonance imaging (MRI) of cortical and hippocampal atrophy supports early diagnosis of AD in MCI subjects, while frontal event-related oscillations (EROs) at delta frequencies (<4Hz) a...

In the last decade, the brain's oscillatory responses have invaded the literature. The studies on delta (0.5-3.5Hz) oscillatory responses in humans upon application of cognitive paradigms showed that delta oscillations are related to cognitive processes, mainly in decision making and attentional processes. The present manuscript comprehensively rev...

Brain oscillations in the gamma frequency band, - i.e. oscillations greater than 25 Hz - have attracted increasing attention over the last few decades in the research of sensory-cognitive processes. In the neuroscience research literature, a great number of reports aim to describe the functional correlates of oscillatory responses in the gamma freq...

The application of the concept and methods of brain oscillations has been an important research area in neurosciences. In the last decades, besides the application in cognitive processes, the study of changes in brain oscillations in diseases has also became an important focal point of research. In the present paper, some remarkable examples in thr...

The present report is a trial to survey analysis and applications of brain oscillations in cognitive impairment for opening the way to a new take off in research on brain oscillation. Although the number of papers related to brain oscillations rapidly increases, it is important to indicate the common principles governing the functioning of brain os...

The effect of lithium on neurocognition is not still fully explored. Brain oscillatory activity is altered in bipolar disorder. We aimed to assess the oscillatory responses of euthymic bipolar patients and how they are affected by lithium monotherapy. Event-related oscillations in response to visual target stimulus during an oddball paradigm in 16...

The present research aims to show that the occurrence of alpha blocking or event-related desynchronization (ERD) strongly depends on the amplitude and also on the phase angle of alpha activity at the stimulus onset. Simple visual stimulation was presented to 17 healthy subjects during EEG recording. An O-2 electrode was used for analysis with a 32...

Decreased delta oscillation upon cognitive load is common in patients with Alzheimer‘s disease, mild cognitive impairment, and schizophrenia. However, there is no previous study analyzing the delta responses in euthymic medication-free patients with bipolar disorder. Participants comprised 22 euthymic medication-free patients with DSM-IV diagnoses...

Since the beginning of the last century, the localization of brain function is presented by Brodmann areas, or maps that are a result of anatomic organization. They are used in order to give a global idea of cortical structures for given sensory cognitive functions. In the last decades, the analysis of brain oscillations gained high importance for...

This report presents six cardinal results obtained with methods of oscillatory brain dynamics in euthymic and manic bipolar patients in comparison to healthy controls. Measurements include changes in oscillatory response activities in the theta, alpha, beta and gamma frequency ranges. The analysis shows that spontaneous and response activities in t...

Brain oscillations have gained tremendous importance in neuroscience during recent decades as functional building blocks of sensory–cognitive processes. Research also shows that event-related oscillations (EROs) in “alpha,” “beta,” “gamma,” “delta,” and “theta” frequency windows are highly modified in pathological brains, especially in patients wit...

This report presents six cardinal results obtained with methods of oscillatory brain dynamics in euthymic and manic bipolar patients in comparison to healthy controls. Measurements include changes in oscillatory response activities in the theta, alpha, beta, and gamma frequency ranges. The analysis shows that spontaneous and response activities in...

Alzheimer's disease (AD) is a devastating neurodegenerative dementing illness. Early diagnosis at the prodromal stage is an important topic of current research. Significant advances were recently made in the validation process of several biomarkers, including structural/amyloid imaging, cerebrospinal fluid measurements, and glucose positron emissio...

Method and concepts of brain oscillations pervade the neuroscience literature, especially in cognitive processes. Electrophysiological changes in patients with cognitive impairment will provide fundamental knowledge, not only for clinical studies but also, in turn, for understanding cognitive processes in healthy subjects. This review includes desc...

This survey covers the potential use of neurophysiological changes as a biomarker in four neuropsychiatric diseases (attention deficit hyperactivity disorder (ADHD), Alzheimer's disease (AD), bipolar disorder (BD), and schizophrenia (SZ)). Great developments have been made in the search of biomarkers in these disorders, especially in AD. Neverthele...

The term "brain (or neural) oscillations" refers to the rhythmic and/or repetitive electrical activity generated spontaneously and in response to stimuli by neural tissue in the central nervous system. The importance of brain oscillations in sensory-cognitive processes has become increasingly evident. It has also become clear that event-related osc...

Mild cognitive impairment (MCI) is considered as a prodromal stage for Alzheimer's disease (AD) in the majority of cases. Event-related oscillations might be used for detection of cognitive deficits. Our group's earlier results showed diminished delta visual and auditory target oscillatory responses in AD, and we investigated whether this prevails...

The aim of the present study was to investigate the role of beta oscillatory responses upon cognitive load in healthy subjects and in subjects with mild cognitive impairment (MCI). The role of beta oscillations upon cognitive stimulation is least studied in comparison to other frequency bands. The study included 17 consecutive patients with MCI (me...

Theta oscillations are related to cognitive functions and reflect functional integration of frontal and medial temporal structures into coherent neurocognitive networks. This study assessed event-related theta oscillations in medication-free, euthymic patients with bipolar disorder upon auditory oddball paradigm. Twenty-two DSM-IV euthymic bipolar...

This report presents six cardinal results obtained with methods of oscillatory brain dynamics in euthymic and manic bipolar patients in comparison to healthy controls. Measurements include changes in oscillatory response activities in the theta, alpha, beta, and gamma frequency ranges. The analysis shows that spontaneous and response activities in...

Export Date: 28 May 2013, Source: Scopus

Cited By (since 1996):1, Export Date: 28 May 2013, Source: Scopus

This report describes a new strategy to analyze and interpret the fine structure of the human brain's gamma oscillations between the frequency ranges of 28 to 48 Hz. There are at least 3-4 phase/time-locked gamma responses within the 28-45-Hz frequency window. Late responses starting around 300 ms are probably responses that are conveyed over retic...

Aim of the review: Questions related to the genesis and functional correlates of the brain's alpha oscillations around 10Hz (Alpha) are one of the fundamental research areas in neuroscience. In recent decades, analysis of this activity has been not only the focus of interest for description of sensory-cognitive processes, but has also led to trial...

AIM OF THE REPORT: In the companion report (Başar, this volume), the physiological fundaments of alpha activity in integrative brain function are described. The present report is a review of the significant role of alpha activity in memory and cognitive processes in healthy subjects, and in cognitive impairment. The role of neurotransmitters is als...

Brain's alpha activity and alpha responses belong to major electrical signals that are related to sensory/cognitive signal processing. The present study aims to analyze the spontaneous alpha activity and visual evoked alpha response in drug free euthymic bipolar patients. Eighteen DSM-IV euthymic bipolar patients (bipolar I n = 15, bipolar II n = 3...

Visual delta event-related (ERO) and evoked oscillations (EO) of Alzheimer patients (AD) are different than healthy. In the present study, the analysis is extented to include auditory ERO and EO in AD. The rationale is to reveal whether the auditory ERO delta responses are also reduced, and whether this is a general phenomenon in Alzheimer patients...

Purpose – The conceptual ideas of Hebb, Heisenberg, and Feynman are embedded in the framework Hayek's so-called New Psychology. The present survey tries to bridge these concepts. Methodology – A theoretical and empirical informed approach. Findings – The theory of D. O. Hebb opened the way to “Neurobiology of Learning” in the past century. The S-Ma...

What is the importance of the Cartesian system in the development of science? What is the importance of philosophy in today’s science? Who are the philosophers? Charles Darwin was a philosopher. Einstein was a philosopher. Norbert Wiener and Werner Heisenberg were philosophers, but they were new Cartesian philosophers. Bergson and von Weizsäcker ar...

Some of the important new features of the present book related to ­physical-mathematical frameworks/models are described in Chaps. 14, 15 and 16. We propose new Cartesian frameworks in the twenty-first century. The aim of this chapter and Chap. 24 is to propose new models of thought on ­brain-body-mind integration. The first model is an adaptation...

The brain is the most complex system known to us in the universe, and previous chapters have presented empirical evidence related to the dynamics of the brain, i.e., a biological system that is continuously changing. Assuming that the brain is an organ that also controls our mind and body, the understanding of brain dynamics should help in the sear...

By proposing the nebulous Cartesian system it is necessary to accumulate knowledge on electrophysiology, anatomy, learning processes, and all physiological settings and store them on several levels of a multiple coordinate system of the nebulous Cartesian system. During the work of the brain several parameters and entities related to brain function...

Brain research is one of the last great frontiers in the biological sciences. The unraveling of its mysteries is comparable in complexity and intellectual challenge to the research in elementary particle research or astrophysics.

Chapter 6 provided an analysis of the essentials of dynamics in the sensory and cognitive processes of the brain. This includes basic studies in the both the human and animal brain, demonstrating that oscillatory activities in the delta, theta, alpha, beta, and gamma bands govern control and communication processes in the brain. Accordingly, these...

Chronological evolution of our conceptual framework evolved in the last 20–25 years and is based on empirical foundations from several laboratories.

Chapter 14 explained the view of Einstein related to quantum physics. According to this view, as in quantum physics, laws in cognitive processing are valid for great congregations of individual units. They are valid not for single neurons, but for neural populations. What applies to quantum mechanics also applies to the dynamics of chaotic systems....

The autonomic nervous system, which regulates what we usually call our innards, is the part of the body linked with the brain. The autonomic nervous system regulates our vital functions without conscious control. We breathe, our heart beats, our stomach digests, and our bladder muscles contract. Further, we secrete saliva, insulin, and digestive en...

According to Fuster (1995a), the cognitive functions of the frontal cortex, as with any part of the neocortex, consist of the activation and processing within and between networks of representation, or memory networks. Those networks are widely distributed and highly specific, defined by their synaptic structure and connectivity. Thus, the memory c...

According to the encyclopedia, mind refers to the collective aspects of intellect and consciousness that are manifest in some combination of thought, perception, emotion, will, and imagination.

In physics, two perfect clocks at two distant points should show exactly the same time. However, there are, according to Einstein, good clocks and bad clocks. “Good” clocks are synchronized and always show exactly the same time even when they are spatially separated. In the brain, various clocks are oscillating with several discrete frequencies. Th...

Previous chapters have shown how one can approach functional correlates of brain oscillations; that the oscillations in alpha, beta, theta, etc., are dependent on the modality of sensory–cognitive events; that, depending both on topology and input modality, the brain response oscillations react with various ensembles of multiple oscillations. Chaps...