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Öğe Investigation of hemispheric asymmetry in alzheimer’s disease patients during resting state revealed by fnirs(2024) Mızrak, Hazel Gül; Dikmen, Merve; Hanoğlu, Lütfü; Şakul, Bayram UfukAlzheimer's disease (AD) is characterized by the gradual deterioration of brain structures and changes in hemispheric asymmetry. Meanwhile, healthy aging is associated with a decrease in functional hemispheric asymmetry. In this study, functional connectivity analysis was used to compare the functional hemispheric asymmetry in eyes-open resting-state fNIRS data of 16 healthy elderly controls (mean age: 60.4 years, MMSE (Mini-Mental State Examination): 27.3 ± 2.52) and 14 Alzheimer's patients (mean age: 73.8 years, MMSE: 22 ± 4.32). Increased interhemispheric functional connectivity was found in the premotor cortex, supplementary motor cortex, primary motor cortex, inferior parietal cortex, primary somatosensory cortex, and supramarginal gyrus in the control group compared to the AD group. The study revealed that the control group had stronger interhemispheric connectivity, leading to a more significant decrease in hemispheric asymmetry than the AD group. The results show that there is a difference in interhemispheric functional connections at rest between the Alzheimer's group and the control group, suggesting that functional hemispheric asymmetry continues in Alzheimer's patients.Öğe Resting state electroencephalographic alpha rhythms are sensitive to Alzheimer's disease mild cognitive impairment progression at a 6-month follow-up(2024) Babiloni, Claudio; Jakhar, Dharmendra; Tucci, Federico; Del Percio, Claudio; Lopez, Susanna; Soricelli, Andrea; Salvatore, Marco; Ferri, Raffaele; Catania, Valentina; Massa, Federico; Arnaldi, Dario; Famà, Francesco; Güntekin, Bahar; Yener, Görsev; Stocchi, Fabrizio; Vacca, Laura; Marizzoni, Moira; Giubilei, Franco; Yıldırım, Ebru; Hanoğlu, Lütfü; Hünerli, Duygu; Frisoni, Giovanni B.; Noce, GiuseppeAre posterior resting-state electroencephalographic (rsEEG) alpha rhythms sensitive to the Alzheimer's disease mild cognitive impairment (ADMCI) progression at a 6-month follow-up? Clinical, cerebrospinal, neuroimaging, and rsEEG datasets in 52 ADMCI and 60 Healthy old seniors (equivalent groups for demographic features) were available from an international archive (www.pdwaves.eu). The ADMCI patients were arbitrarily divided into two groups: REACTIVE and UNREACTIVE, based on the reduction (reactivity) in the posterior rsEEG alpha eLORETA source activities from the eyes-closed to eyes-open condition at ? ?10% and ?10%, respectively. 75% of the ADMCI patients were REACTIVE. Compared to the UNREACTIVE group, the REACTIVE group showed (1) less abnormal posterior rsEEG source activity during the eyes-closed condition and (2) a decrease in that activity at the 6-month follow-up. These effects could not be explained by neuroimaging and neuropsychological biomarkers of AD. Such a biomarker might reflect abnormalities in cortical arousal in quiet wakefulness to be used for clinical studies in ADMCI patients using 6-month follow-ups.Öğe rTMS reduces delta and increases theta oscillations in Alzheimer's disease: A visual-evoked and event-related potentials study(Wiley, 2024) Velioğlu, Halil Aziz; Düdükçü, Esra Zeynep; Hanoğlu, Lütfü; Güntekin, Bahar; Aktürk, Tuba; Yuluğ, BurakBackground: Repetitive transcranial magnetic stimulation (rTMS) has emerged as a promising alternative therapy for Alzheimer's disease (AD) due to its ability to modulate neural networks and enhance cognitive function. This treatment offers the unique advantage of enabling real-time monitoring of immediate cognitive effects and dynamic brain changes through electroencephalography (EEG).Objective: This study focused on exploring the effects of left parietal rTMS stimulation on visual-evoked potentials (VEP) and visual event-related potentials (VERP) in AD patients.Methods: Sixteen AD patients were recruited for this longitudinal study. EEG data were collected within a Faraday cage both pre- and post-rTMS to evaluate its impact on potentials.Results: Significant alterations were found in both VEP and VERP oscillations. Specifically, delta power in VEP decreased, while theta power in VERP increased post-rTMS, indicating a modulation of brain activities.Discussion: These findings confirm the positive modulatory impact of rTMS on brain activities in AD, evidenced by improved cognitive scores. They align with previous studies highlighting the potential of rTMS in managing hyperexcitability and oscillatory disturbances in the AD cortex.Conclusion: Cognitive improvements post-rTMS endorse its potential as a promising neuromodulatory treatment for cognitive enhancement in AD, thereby providing critical insights into the neurophysiological anomalies in AD and possible therapeutic avenues.Öğe Poor reactivity of posterior electroencephalographic alpha rhythms during the eyes open condition in patients with dementia due to Parkinson's disease(Elsevier Inc., 2024) Babiloni, Claudio; Noce, Giuseppe; Tucci, Federico; Jakhar, Dharmendra; Ferri, Raffaele; Panerai, Simonetta; Catania, Valentina; Soricelli, Andrea; del Percio, ClaudioHere, we hypothesized that the reactivity of posterior resting-state electroencephalographic (rsEEG) alpha rhythms during the transition from eyes-closed to -open condition might be lower in patients with Parkinson's disease dementia (PDD) than in patients with Alzheimer's disease dementia (ADD). A Eurasian database provided clinical-demographic-rsEEG datasets in 73 PDD patients, 35 ADD patients, and 25 matched cognitively unimpaired (Healthy) persons. The eLORETA freeware was used to estimate cortical rsEEG sources. Results showed substantial (greater than ?10%) reduction (reactivity) in the posterior alpha source activities from the eyes-closed to the eyes-open condition in 88% of the Healthy seniors, 57% of the ADD patients, and only 35% of the PDD patients. In these alpha-reactive participants, there was lower reactivity in the parietal alpha source activities in the PDD group than in the healthy control seniors and the ADD patients. These results suggest that PDD patients show poor reactivity of mechanisms desynchronizing posterior rsEEG alpha rhythms in response to visual inputs. That neurophysiological biomarker may provide an endpoint for (non) pharmacological interventions for improving vigilance regulation in those patients.Öğe The effects of cognitive, physical, and somatosensory rehabilitation after right temporo-parietal tumor resection on cognitive, motor, somatosensory, and electrophysiological parameters: A case report(Taylor and Francis Ltd., 2023) Sarıcaoğlu, Mevhibe; Hanoğlu, Lütfü; Güntekin, Bahar; Özkara, ÇiğdemIntroduction: This report examines the effects of a multimodal rehabilitation program which includes cognitive, physical, and somatosensory rehabilitation after right temporo-parietal tumor resection on cognitive, motor, somatosensory, and electrophysiological parameters. Case Description: A 22-year-old patient presented with sensory loss in the dominant left hand and reduced writing ability after right temporo-parietal lobe resection. Cognitive, motor, and sensory evaluations were carried out pre and post-treatment. The patient’s spontaneous electroencephalo-gram (EEG) and an EEG during application of transcutaneous electrical nerve stimulation (TENS) (TENS EEG) were recorded. As a reference for the patient’s electrophysiological values, EEGs of 4 healthy individuals were also taken. Over a period of 1 year, the patient received multimodal rehabilitation which includes cognitive, physical, and somato-sensory rehabilitation on 2 days each week. Outcomes: An improvement of the patient’s cognitive capacities, motor strength, superficial, deep and cortical sensations was achieved. After rehabilitation, an increase in parietal and occipital alpha activity as well as in frontal and parietal beta activity was seen both in spontaneous EEG and in TENS EEG. With increasing TENS intensity, alpha and beta power increased as well. Conclusion: Our findings suggest that a multimodal rehabilitation program may improve cognitive, sensory, and motor effects after resection due to tumor surgery.Öğe Abnormal cross frequency coupling of brain electroencephalographic oscillations related to visual oddball task in parkinson's disease with mild cognitive impairment(SAGE Publications Inc., 2023) Bayraktaroğlu, Zübeyir; Aktürk, Tuba; Yener, Görsev; de Graaf, Tom A.; Hanoğlu, Lütfü; Yıldırım, Ebru; Hünerli Gündüz, Duygu; Kıyı, İlayda; Sack, Alexander T.; Babiloni, Claudio; Güntekin, BaharParkinson's disease (PD) is a movement disorder caused by degeneration in dopaminergic neurons. During the disease course, most of PD patients develop mild cognitive impairment (PDMCI) and dementia, especially affecting frontal executive functions. In this study, we tested the hypothesis that PDMCI patients may be characterized by abnormal neurophysiological oscillatory mechanisms coupling frontal and posterior cortical areas during cognitive information processing. To test this hypothesis, event-related EEG oscillations (EROs) during counting visual target (rare) stimuli in an oddball task were recorded in healthy controls (HC; N = 51), cognitively unimpaired PD patients (N = 48), and PDMCI patients (N = 53). Hilbert transform served to estimate instantaneous phase and amplitude of EROs from delta to gamma frequency bands, while modulation index computed ERO phase-amplitude coupling (PAC) at electrode pairs. As compared to the HC and PD groups, the PDMCI group was characterized by (1) more posterior topography of the delta-theta PAC and (2) reversed delta-low frequency alpha PAC direction, ie, posterior-to-anterior rather than anterior-to-posterior. These results suggest that during cognitive demands, PDMCI patients are characterized by abnormal neurophysiological oscillatory mechanisms mainly led by delta frequencies underpinning functional connectivity from frontal to parietal cortical areas.Öğe Evaluation of cognitive functions in adult individuals with COVID-19(Springer-Verlag Italia s.r.l., 2023) Akıncı, Büşra; Erkan Oğul, Özden; Hanoğlu, Lütfü; Kulaç, Betül; Ören, Damla; Ulu, Oğulcan; Basançelebi, BerkanBackground and Purpose: Cognitive deficits that are associated with coronavirus disease 2019 (COVID-19) and occur in the acute period are gaining importance. While most studies have focused on the elderly severely affected during acute infection, it remains unclear whether mild to moderate COVID-19 results in cognitive deficits in young patients. This study aims to evaluate the post-infection cognitive functions of young adults with mild to moderate symptoms of COVID-19. Methods: A total of 100 adults with similar age and educational background were included in the study. Half of those had been infected with COVID-19 in the last 60 days (N = 50), and the other half had not (N = 50). Global cognitive skills of the participants were evaluated through Montreal Cognitive Assessment Scale (MoCA) and Clock-Drawing Test; memory functions with Öktem Verbal Memory Processes Test (Ö-VMPT); attention span with Digit Span Test; executive functions with Fluency Tests, Stroop Test, and Trail Making Test; visual perceptual skills with Rey Osterrieth Complex Figure Test (ROCF); and neuropsychiatric status with Neuropsychiatric Inventory (NPI). Evaluations were performed in the experimental group for 21 to 60 days from the onset of the disease, and throughout the study, in the control group. Results: It was found that global cognitive skills, verbal memory, visual memory, executive function, and neuropsychiatric status were affected during COVID-19 (p < 0.05). Conclusion: When the cases were analyzed according to disease severity, no relationship was found between cognitive deficits and disease severity.Öğe Relationship between default mode network and resting-state electroencephalographic alpha rhythms in cognitively unimpaired seniors and patients with dementia due to Alzheimer's disease(Oxford University Press Inc., 2023) Babiloni, Claudio; Lopez, Susanna; Noce, Giuseppe; Ferri, Raffaele; Panerai, Simonetta; Catania, Valentina; Soricelli, Andrea; Salvatore, Marco; Nobili, Flavio; Arnaldi, Dario; Fama, Francesco; Massa, Federico; Buttinelli, Carla; Giubilei, Franco; Stocchi, Fabrizio; Vacca, Laura; Marizzoni, Moira; D'Antonio, Fabrizia; Bruno, Giuseppe; de Lena, Carlo; Güntekin, Bahar; Yıldırım, Ebru; Hanoğlu, Lütfü; Yener, Görsev; Yerlikaya, Deniz; Taylor, John Paul; Schumacher, Julia; Mckeith, Ian; Bonanni, Laura; Pantano, Patrizia; Piervincenzi, Claudia; Petsas, Nikolaos; Frisoni, Giovanni B.; del Percio, Claudio; Carducci, FilippoHere we tested the hypothesis of a relationship between the cortical default mode network (DMN) structural integrity and the resting state electroencephalographic (rsEEG) rhythms in patients with Alzheimer's disease with dementia (ADD). Clinical and instrumental datasets in 45 ADD patients and 40 normal elderly (Nold) persons originated from the PDWAVES Consortium (www.pdwaves.eu). Individual rsEEG delta, theta, alpha, and fixed beta and gamma bands were considered. Freeware platforms served to derive (1) the (gray matter) volume of the DMN, dorsal attention (DAN), and sensorimotor (SMN) cortical networks and (2) the rsEEG cortical eLORETA source activities. We found a significant positive association between the DMN gray matter volume, the rsEEG alpha source activity estimated in the posterior DMN nodes (parietal and posterior cingulate cortex), and the global cognitive status in the Nold and ADD participants. Compared with the Nold, the ADD group showed lower DMN gray matter, lower rsEEG alpha source activity in those nodes, and lower global cognitive status. This effect was not observed in the DAN and SMN. These results suggest that the DMN structural integrity and the rsEEG alpha source activities in the DMN posterior hubs may be related and predict the global cognitive status in ADD and Nold persons.Öğe Classification of Parkinson's disease with dementia using phase locking factor of event-related oscillations to visual and auditory stimuli(IOP Publishing Ltd, 2023) Tülay, Emine Elif; Yıldırım, Ebru; Aktürk, Tuba; Güntekin, BaharObjective. In the last decades, machine learning approaches have been widely used to distinguish Parkinson’s disease (PD) and many other neuropsychiatric diseases. They also speed up the clinicians and facilitate decision-making for several conditions with similar clinical symptoms. The current study attempts to detect PD with dementia (PDD) by event-related oscillations (EROs) during cognitive processing in two modalities, i.e. auditory and visual. Approach. The study was conducted to discriminate PDD from healthy controls (HC) using event-related phase-locking factors in slow frequency ranges (delta and theta) during visual and auditory cognitive tasks. Seventeen PDD and nineteen HC were included in the study, and linear discriminant analysis was used as a classifier. During classification analysis, multiple settings were implemented by using different sets of channels (overall, fronto-central and temporo-parieto-occipital (TPO) region), frequency bands (delta-theta combined, delta, theta, and low theta), and time of interests (0.1-0.7 s, 0.1-0.5 s and 0.1-0.3 s for delta, delta-theta combined; 0.1-0.4 s for theta and low theta) for spatial-spectral-temporal searchlight procedure. Main results. The classification performance results of the current study revealed that if visual stimuli are applied to PDD, the delta and theta phase-locking factor over fronto-central region have a remarkable contribution to detecting the disease, whereas if auditory stimuli are applied, the phase-locking factor in low theta over TPO and in a wider range of frequency (1-7 Hz) over the fronto-central region classify HC and PDD with better performances. Significance. These findings show that the delta and theta phase-locking factor of EROs during visual and auditory stimuli has valuable contributions to detecting PDD.Öğe Enhancing memory capacity by experimentally slowing theta frequency oscillations using combined EEG-tACS(Nature Portfolio, 2022) Aktürk, Tuba; de Graaf, Tom A.; Güntekin, Bahar; Hanoğlu, Lütfü; Sack, Alexander T.he coupling of gamma oscillation (similar to 40+ Hz) amplitude to the phase of ongoing theta (similar to 6 Hz) oscillations has been proposed to be directly relevant for memory performance. Current theories suggest that memory capacity scales with number of gamma cycles that can be fitted into the preferred phase of a theta cycle. Following this logic, transcranial alternating current stimulation (tACS) may be used to adjust theta cycles (increasing/decreasing theta frequency) to decrease or increase memory performance during stimulation. Here, we used individualized EEG-informed theta tACS to (1) experimentally "slow down" individual theta frequency (ITF), (2) evaluate cognitive after effects on a battery of memory and learning tasks, and (3) link the cognitive performance changes to tACS-induced effects on theta-band oscillations as measured by post EEG. We found frequencyand task-specific tACS after effects demonstrating a specific enhancement in memory capacity. This tACS-induced cognitive enhancement was specific to the visual memory task performed immediately after tACS offset, and specific to the ITF-1 Hz (slowing) stimulation condition and thus following a protocol specifically designed to slow down theta frequency to enhance memory capacity. Follow-up correlation analyses in this group linked the enhanced memory performance to increased left frontalparietal theta-band connectivity. Interestingly, resting-state theta power immediately after tACS offset revealed a theta power increase not for the ITF-1 Hz group, but only for the ITF group where the tACS frequency was 'optimal' for entrainment. These results suggest that while individually calibrated tACS at peak frequency maximally modulates resting-state oscillatory power, tACS stimulation slightly below this optimal peak theta frequency is better suited to enhance memory capacity performance. Importantly, our results further suggest that such cognitive enhancement effects can last beyond the period of stimulation and are linked to increased network connectivity, opening the door towards more clinical and applied relevance of using tACS in cognitive rehabilitation and/or neurocognitive enhancement.Öğe Reactivity of posterior cortical electroencephalographic alpha rhythms during eyes opening in cognitively intact older adults and patients with dementia due to Alzheimer's and Lewy body diseases(Elsevier Inc., 2022) Babiloni, Claudio; Lorenzo, Ivan; Lizio, Roberta; Lopez, Susanna; Tucci, Federico; Ferri, Raffaele; Soricelli, Andrea; Nobili, Flavio; Arnaldi, Dario; Famà, Francesco; Buttinelli, Carla; Giubilei, Franco; Cipollini, Virginia; Onofrj, Marco; Stocchi, Fabrizio; Vacca, Laura; Fuhr, Peter; Gschwandtner, Ute; Ransmayr, Gerhard; Aarsland, Dag; Parnetti, Lucilla; Marizzoni, Moira; D'Antonio, Fabrizia; De Lena, Carlo; Güntekin, Bahar; Yıldırım, Ebru; Hanoğlu, Lütfü; Yener, Görsev; Hünerli Gündüz, Duygu; Taylor, John Paul; Schumacher, Julia; McKeith, Ian; Frisoni, Giovanni B.; De Pandis, Maria Francesca; Bonanni, Laura; Percio, Claudio Del; Noce, GiuseppePlease modify the Abstract as follows:Here we tested if the reactivity of posterior resting-state electroencephalographic (rsEEG) alpha rhythms from the eye-closed to the eyes-open condition may differ in patients with dementia due to Lewy Bodies (DLB) and Alzheimer's disease (ADD) as a functional probe of the dominant neural synchronization mechanisms regulating the vigilance in posterior visual systems.We used clinical, demographical, and rsEEG datasets in 28 older adults (Healthy), 42 DLB, and 48 ADD participants. The eLORETA freeware was used to estimate cortical rsEEG sources.Results showed a substantial (> -10%) reduction in the posterior alpha activities during the eyes-open condition in 24 Healthy, 26 ADD, and 22 DLB subjects. There were lower reductions in the posterior alpha activities in the ADD and DLB groups than in the Healthy group. That reduction in the occipital region was lower in the DLB than in the ADD group.These results suggest that DLB patients may suffer from a greater alteration in the neural synchronization mechanisms regulating vigilance in occipital cortical systems compared to ADD patients.Öğe Therapeutic role of repetitive transcranial magnetic stimulation in Alzheimer's and Parkinson's disease: Electroencephalography microstate correlates(Frontiers Media SA, 2022) Hanoğlu, Lütfü; Toplutaş, Eren; Sarıçaoğlu, Mevhibe; Velioğlu, Halil Aziz; Yıldız, Sultan; Yuluğ, BurakIntroduction: The microstate analysis is a method to convert the electrical potentials on the multi-channel electrode array to topographical electroencephalography (EEG) data. Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive method that can modulate brain networks. This study explores the pathophysiological changes through microstate analysis in two different neurodegenerative diseases, Alzheimer’s (AD) and Parkinson’s disease (PD), characterized by motor and cognitive symptoms and analysis the effect of rTMS on the impaired cognitive and motor functions. Materials and Methods: We included 18 AD, 8 PD patients, and 13 age-matched controls. For both groups, we applied 5 Hz rTMS on the left pre-SMA in PD patients while 20 Hz rTMS on the left lateral parietal region in AD patients. Each patient was re-evaluated 1 week after the end of the sessions, which included a detailed clinical evaluation and measurement of EEG microstates. Results: At the baseline, the common findings between our AD and PD patients were altered microstate (MS) B, MS D durations and transition frequencies between MS A–MS B, MS C–MS D while global explained variance (GEV) ratio and the extent and frequency of occurrence of MS A, MS B, and MS D were separately altered in AD patients. Although no specific microstate parameter adequately differentiated between AD and PD patients, we observed significant changes in MS B and MS D parameters in PD patients. Further, we observed that Mini-Mental State Examination (MMSE) performances were associated with the transition frequencies between MS A–MS B and MS C–MS D and GEV ratio. After left parietal rTMS application, we have observed significantly increased visual memory recognition and clock drawing scores after left parietal rTMS application associated with improved microstate conditions prominent, especially in the mean duration of MS C in AD patients. Also, pre-SMA rTMS resulted in significant improvement in motor scores and frequency of transitions from MS D to MS C in PD patients. Conclusion: This study shows that PD and AD can cause different and similar microstate changes that can be modulated through rTMS, suggesting the role of MS parameters and rTMS as a possible combination in monitoring the treatment effect in neurodegenerative diseases.Öğe The multifactorial role of pre-supplementary motor area stimulation in the freezing of gait: An alternative strategy to the classical drug-Target approach(Bentham Science Publishers, 2022) Sarıcaoğlu, Mevhibe; Hanoğlu, Lütfü; Toprak, Güven; Helvacı Yılmaz, Nesrin; Yuluğ, BurakIntroduction: The pre-supplementary motor area (Pre-SMA) plays a pivotal role in the control of voluntary motor control and freezing of gait (FOG) pathophysiological mechanism. Here, we aimed to modulate if the pre-SMA would have beneficial effects on motor and behavioural outcomes in freezing of gait. To test this hypothesis, we examined the left pre-SMA stimulating effect of repetitive Transcranial Magnetic Stimulation (rTMS) on motor, cognitive and behavioural parameters in Parkinson's patients with FOG. Method: The study included 20 Parkinson's patients with FOG (3 females, 17 males) who received the left Pre-SMA rTMS procedure. The clinical assessments were performed on all patients at the baseline and the patients were re-evaluated under the same clinical conditions one week after the end of the sessions. Results & discussion: We found significant improvements in motor, cognitive and behavioural symptoms (p<0.05). The main finding of our study is that Pre-SMA is an attractive stimulation area leading to critical improvement of symptoms of Parkinson' s patients with FOG. Conclusion: The high-frequency rTMS stimulation over the left preSMA has a restorative effect on the motor, cognitive and behavioural symptoms of Parkinson' s patients with FOG.Öğe The therapeutic role of repetitive transcranial magnetic stimulation (rTMS) in parkinsonian visual hallucinations: Electrophysiological correlates(Elsevier Science Ltd, 2019) Hanoğlu, Taha; Hanoğlu, Lütfü; Güntekin, Bahar; Aktürk, Tuba; Yuluğ, BurakWe have evaluated an 82 years old PD patient who has acutely developed VH secondary to acute visual loss that was associated with increased electroencephalographic activity in the gamma range over the parietal, occipital and frontal regions. In this respect, we have tested the therapeutic effect of occipital lobe oriented rTMS application and its electrophysiological correlates that led to significant improvement in the hallucinatory symptomatology of the patient after two weeks. We have revealed that the improved hallucinatory symptoms after rTMS application resolved completely after switching from the pramipexole treatment to L-Dopa indicating that there could be a combined therapeutic effect of L-Dopa and rTMS. Furthermore, Quantitative-Electroencephalography analysis has shown that the therapeutic effects of rTMS and L-Dopa were seen with the improvement of impaired gamma power spectrum. Although the main limitation of this report is that this a single case study and that these findings need to be replicated in a larger sample, e.g., as part of a controlled trial, our present findings help us to enlighten the unknown pathophysiological overlapping between the visual hallucinations in PD and Charles Bonnet Syndrome. Finally, our study revealed increased gamma coherence and power spectrum which is seen with visual hallucinations and improved after the application of 1 Hz rTMS on the occipital lobe. These findings together suggest that rTMS could be used as a therapeutic tool for parkinsonian complex VH and probably due affecting gamma coherence and power spectrum.
