Yuichi Kitaura

Differences in quantitative EEG between frontotemporal dementia and Alzheimer’s disease as revealed by LORETA

OBJECTIVE To determine the electrophysiological characteristics of frontotemporal dementia (FTD) and the distinction with Alzheimers disease (AD). METHODS We performed analyses of global field power (GFP) which is a measure of whole brain electric field strength, and EEG neuroimaging analyses with sLORETA (standardized low resolution electromagnetic tomography), in the mild stages of FTD (n = 19; mean age = 68.11 ± 7.77) and AD (n = 19; mean age = 69.42 ± 9.57) patients, and normal control (NC) subjects (n = 22; mean age = 66.13 ± 6.02). RESULTS In the GFP analysis, significant group effects were observed in the delta (1.5-6.0 Hz), alpha1 (8.5-10.0 Hz), and beta1 (12.5-18.0 Hz) bands. In sLORETA analysis, differences in activity were observed in the alpha1 band (NC > FTD) in the orbital frontal and temporal lobe, in the delta band (AD>NC) in widespread areas including the frontal lobe, and in the beta1 band (FTD > AD) in the parietal lobe and sensorimotor area. CONCLUSIONS Differential patterns of brain regions and EEG frequency bands were observed between the FTD and AD groups in terms of pathological activity. SIGNIFICANCE FTD and AD patients in the early stages displayed different patterns in the cortical localization of oscillatory activity across different frequency bands.

The Cross-Frequency Mediation Mechanism Of Intracortical Information Transactions

In a seminal paper by von Stein and Sarnthein (2000), it was hypothesized that “bottom-up” information processing of “content” elicits local, high frequency (beta-gamma) oscillations, whereas “top-down” processing is “contextual”, characterized by large scale integration spanning distant cortical regions, and implemented by slower frequency (theta-alpha) oscillations. This corresponds to a mechanism of cortical information transactions, where synchronization of beta-gamma oscillations between distant cortical regions is mediated by widespread theta-alpha oscillations. It is the aim of this paper to express this hypothesis quantitatively, in terms of a model that will allow testing this type of information transaction mechanism. The basic methodology used here corresponds to statistical mediation analysis, originally developed by (Baron and Kenny 1986). We generalize the classical mediator model to the case of multivariate complex-valued data, consisting of the discrete Fourier transform coefficients of signals of electric neuronal activity, at different frequencies, and at different cortical locations. The “mediation effect” is quantified here in a novel way, as the product of “dual frequency RV-coupling coefficients”, that were introduced in (Pascual-Marqui et al 2016, http://arxiv.org/abs/1603.05343). Relevant statistical procedures are presented for testing the cross-frequency mediation mechanism in general, and in particular for testing the von Stein & Sarnthein hypothesis.

1-A-D-16. The characteristics of resting-state EEG connectivity in patients with Alzheimer’s disease by the LORETA

Alzheimer’s disease (AD) is characterized by cognitive and memory dysfunctions, and is accompanied by default mode network (DMN) abnormalities. We investigated the neurophysiological basis of these dysfunctions by examining functional connectivity using standardized low resolution electromagnetic tomography (sLORETA). Resting, eyes closed EEGs were recorded from 19 patients with mild AD and 22 healthy control subjects. Electrophysiological connectivity maps between parahippocampal gyri and all other cortical regions were computed, as well as pairwise connectivity among DMN regions. Between-group comparisons in 7 frequency bands were carried out. Beta2 connectivity was marginally decreased between right parahippocampus and right superior frontal gyrus, right precentral gyrus, and right occipital lobe in AD patients. They also showed significantly decreased alpha2 and beta2 connectivity between posterior cingulate gyrus and right inferior parietal lobe within DMN. Previous fMRI studies have shown AD decreased connectivity between parahippocampus, where significant neurological degeneration appears, and other brain regions. The disconnection between the hubs of DMN in sLORETA connectivity suggest AD patients have an abnormal DMN, in agreement with previous fMRI resting state networks studies. sLORETA connectivity provides complimentary information on the neurophysiological dysfunction between parahippocampus and other cortical areas, and on the DMN aberrance in patients with AD.

Hyperactivation of the Frontal Control Network Revealed by Symptom Provocation in Obsessive-Compulsive Disorder Using EEG Microstate and sLORETA Analyses

The aim of this study was to investigate the changes of brain electric field induced by symptom provocation in patients with obsessive-compulsive disorder (OCD) in comparison to healthy controls in the resting state. For this purpose, EEG recordings in conditions of initial rest, clean control, symptom provocation by imaginal exposure, and final rest were used for computing spatiotemporal activity characteristics based on microstate segmentation. Within-group comparisons were significant for the symptom provocation condition: OCD showed high global field power (GFP) and transition rates into a medial frontal microstate, whereas healthy controls showed high frequency of occurrence and high percent of dwelling time for a medial occipitoparietal microstate. Between-group comparisons demonstrated significantly lower GFP and dwelling time for the medial occipitoparietal microstate in OCD in several conditions including initial rest and symptom provocation. In addition, OCD compared to healthy controls showed significant instability of the medial occipitoparietal microstate, with high preference for transitions into the medial frontal microstate. In conclusion, during rest and symptom provocation, OCD patients make preferential use of a medial frontal brain network, with concomitant reduction of use of a medial occipitoparietal network, as shown by dwelling times, explained variance, and dynamic transition rates. These findings support the idea of a possible biological marker for OCD, which might correspond to pathological hyperactivation of the frontal control network.

Functional localization and effective connectivity of cortical theta and alpha oscillatory activity during an attention task

Highlights • sLORETA analyses performed on 14 healthy adults at rest and during an arithmetic task.• Theta and alpha directed connectivity revealed ACC and left IPL as hubs during task.• Information flow between left IFG and STG suggested a feedback loop.

P8.2 Quantitative EEG analysis in severe semantic dementia using low-resolution electromagnetic tomography (LORETA): 4 case series

Introduction: Hemichorea-hemiballisum (HBHC) in patients with hyperglycemia and striatal hyperintensity on T1-weighted MR images is now an accepted clinical entity. It frequently occurs in elderly women, and more than 80% of reported patients have been of Asian descent. A transient, reversible metabolic impairment within the basal ganglion has been considered a possible cause of this disorder. However, the pathogenesis remains unclear. In addition, periodic lateralized epileptiform discharge (PLEDs) on EEG usually indicates an acute and severe cerebral insult, such as CNS infection, tumor, epilepsy, and stroke. Hyperglycemia was not reported in the literature review. Objectives: We reported a rare case of hyperglycemia-related HBHC associated with striatal hyperintensity on T1-weighted MR and PLEDs on EEG. We also discuss the possible pathogenesis. Methods: We reported a 74-year-old with prolonged, uncontrolled DM with HBHC and striatal hyperintensity on T1-weighted MR images. The initial blood glucose, osmolality level and HbA1C were 312 mg/dl, 294 mmol/l and 9.0%, respectively. While aggressive sugar control (around 150 200 mg/dl) improved the severity of HBHC, medication showed poor response. When the PLEDs subsided, but hyperglycemia persisted, the HBHC, although much improved, but still existed. Conclusions: PLEDs on EEG can be found in patients with hyperglycemiaassociated HBHC and striatal hyperintensity on T1-weighted MR images. It may support to the possible “ischemic ” pathogenesis in this special clinical setting.

WS5-2 Pharmaco-EEG application for the evaluation of drug effects on mental disorders

whether acute or chronic, is predominantly demyelinating and is often associated with rapid and relatively complete recovery. However, nerve transection, stretch, or crush is followed by Wallerian degeneration, more delayed and incomplete recovery. The clinical neurophysiological examination may address four pertinent issues: Localization of the injury, pathophysiology of the injury, severity of the dysfunction, and progress of reinnervation The repair processes in peripheral nerve are sprouting of undamaged axons in close proximity of the denervated muscle and the axonal regeneration from the site of nerve injury. While the axonal regereration is only the repair process in complete nerve lesions, both the sprouting and axonal regeneration are the mechanism of recovery in partial traumatic lesions. The motor unit potentials (MUPs) observed in axonal regenerations are nascent MUPs or highly desynchronized MUPs of long duration followed by a separated linked complex subunits potentials and large, fairly normal looking MUPs followed by constituent intervals by small linked potentials are shown in partial lesions. In the application in clinical neurophysiology, the factor of favorable outcome are distal location, preponderance of demyelination, incomplete dysfunction, and prompt reinnervation. The pertinent variables in clinical neurophysiologys are compound action potentials (muscle and/or nerve), motor unit action potentials, and denervation potentials. Analysis of the CMAP in response to stimulation of the distal nerve is the best estimation of severity and also has prognostic information. MUPs of great instability indicates ongoing reinnervation, while high-amplitude MUPs with stable shape on repeated discharges imply that no reinnervation has taken place in this muscle during recent months. However, it is not possible to quantitate defect by the abundance of denervation potentials.

P27-6 Quantitative EEG analysis of electroconvulsive therapy response for senile depression: a case report

Objectives: Depressive patients show cognitive deficits and an impaired ability to modulate emotional states. In order to deeply understand the physiological mechanism of emotional cognitive process in patients with depression, it is important to investigate the activated cortical networks, especially to detect the interactions between different cortical sites. Methods: Granger Causality is one of best-established approaches which can express the direction of interrelation between different brain regions. Since the classical estimation of Granger Causality requires stationary signal, we introduced a windowing Granger causality in this study to detect the dynamic casual relations within the cortical network during cognitive process on facial emotion in slow bands (delta and theta). According to the ERP result in our previous study, we performed a successive set of 200 ms windows without overlap after stimulus onset, and in each window the underlying stochastic processes were considered to be locally stationary. Event-related electroencephalograms were recorded from 16 depressed and 16 healthy control subjects during their performing in the ‘study-judgment’ task of facial emotion. Results: Significant between-group effect occurs mainly in first and third time windows after stimulus onset on emotional cognition process. Depressive patients showed reduced activation between frontal hemispheres in both delta and theta bands, but more information flew into the left temporal sites than controls during the first time window (1 200 ms). While in the third time window (401 600 ms), controls showed increased activation and dense webs of directed interactions from anterior to posterior cortical sites in the delta band, but not in the theta band. Conclusion: Early time abnormal information inflow in left temporal region in depression may imply the overactivity of amygdala which is important for emotional modulation. The altered frontal interaction in depression with other brain region may contribute to impaired affect modulation.

P24-15 A change of the three-dimensional brain electric activity by the LI4 (Heku) acupuncture stimulation

Objective: Various activities have used to prevent dementia. We have not checked technique for effect of activities for subjects. Therefore, EEG analysis is useful methods to check brain activity. We measured two bands, alpha and beta wave and calculated those amount. The alpha band was divided into three subdivisions (slow; 7.8 9.8 Hz, middle; 9.8 11.8 Hz and fast; 11.8 13.7 Hz) which were analyzed separately. Methods: Subjects were healthy four men and four women (22.0±0.8 years old). Data is taken into the personal computer by sampling frequency 1 kHz by using the DAQ terminal-410 (INTERCROSS Co. Ltd. Tokyo). The electrode was put on F3, F4 point and C3, C4 point according to 10 20 international methods. The individual was asked to open their eyes and to pay attention to 10 figures which were presented on a computer screen for 30 seconds. Following 30 seconds, mentally review the figures which had just been displayed. The present study obtains approval through the examination of the Kanazawa University medicine ethics committee. Results: Amount of all three alpha bands have decreased during memory. The Most decreased band was middle wave, and the next was slow wave. After task, most of subjects EEG returned to the state before intervention. On the other hand, the beta wave increased during memory. Conclusions: When the healthy adult memorizing, slow and middle alpha wave decreased especially. On the other hand, beta wave increased. This result shows that memorizing cause the modulation in the high frequency element of the brain activity. Because of this modulation, we can say that whether stimulation is being input to the healthy elderly adult and the patient with dementia or not, can be judged from the EEG.

P37-8 Comparison between mild Alzheimer's disease and frontotemporal dementia using quantitative EEG

F. Vecchio1, C. Babiloni2,3, G. Frisoni4, M. Pievani4, C. De Carli5, R. Ferri6, F. Vernieri7, R. Lizio8, P.M. Rossini3,7 1A.Fa.R., Dip. Neurosci. Osp. FBF; Isola Tiberina, Rome, Italy, 2Department of Biomedical Sciences, University of Foggia, Foggia, Italy, 3Casa di Cura San Raffaele Cassino, Italy, 4IRCCS “S. Giovanni di Dio-F.B.F.”, Brescia, Italy, 5Department of Neurology and Imaging of Dementia and Aging Laboratory, Center for Neuroscience, University of California at Davis, Sacramento, USA, 6IRCCS Oasi, Troina, Italy, 7Clin. Neurol. University “Campus Biomedico” Rome, Italy, 8IRCCS San Raffaele Pisana, Rome, Italy