MCI, indicating delta responses may predict the conversion from MCI to AD. In conclusion, event-related brain oscillations are important correlates of cognitive processes and have the potential to be investigated as a candidate biomarker for screening of large populations at risk, as well as in the diagnosis and course of AD. doi:10.1016/j.ijpsycho.2016.07.073
476
Delta and theta oscillatory activity in aging Gorsev G. Yener
Department of Neurology, Faculty of Medicine, Dokuz Eylul University, Izmir, Turkey
Brain Dynamics Multidisciplinary Research Center, Dokuz Eylul Univer-sity, Izmir, Turkey
Department of Neurosciences, Institute of Health Sciences, Dokuz Eylul University, Izmir, Turkey
Brain Dynamics, Cognition and Complex Systems Research Center, Istanbul Kultur University, Istanbul, Turkey
The present study was undertaken to assess the effect of aging on visual delta and theta event-related oscillations (EROs) in younger and older healthy elderly subjects. We hypothesized that delta and theta EROs were affected by age-related changes, as resting-state EEG and event-related potentials (ERPs) undergo substantial change during aging.Twenty-five younger healthy elderly subjects (mean age: 63.88 ± 3.55 years) and 25 gender- and education-matched older healthy elderly subjects (mean age: 79.56 ± 4.72 years) participated. EEG was recorded from F3, Fz, F4, C3, Cz, C4, P3, Pz, P4, O1, Oz and O2 electrode sites using a classical visual oddball paradigm. Maximum peak-to-peak amplitudes of delta (0.5–3 Hz) and theta (4-7 Hz) EROs in response to target stimulation were measured. The repeated measures ANOVA analysis included 2-level GROUP (younger healthy elderly and older healthy elderly) as between-subject factors, and anterior-posterior distribution (AP [4 levels] = frontal, central, parietal, occipital), and lateral distribution (LAT [3 levels] = left, midline, right) as within-subject factors. Repeated measures ANOVAs were run separately for delta and theta ERO responses. Independent t-tests were applied for post-hoc analysis.
Repeated measures ANOVA revealed main GROUP effects on peak-to-peak amplitudes of delta [F(1.48) = 9.229; p = 0.004) and theta EROs [F(1.48) = 5.050; p = 0.029]. Peak-to-peak amplitudes of delta EROs were lower in older healthy elderly subjects compared to younger healthy elderly group over all frontal, central and parietal electrode sites (pb 0.008). Furthermore, older healthy elderly subjects showed lower amplitudes of theta EROs compared to the younger group over all frontal electrode locations (pb 0.02). Moreover, moderate negative correlations were observed between age and delta ERO responses in all frontal, central and parietal locations, indicating that diffuse reductions in delta responses occur with increasing age [-0.34b r b -0.44, all = "" p = "" N In the present study, older healthy elderly subjects demonstrated significantly lower delta EROs over all frontal, central and parietal locations and lower theta EROs in all frontal locations compared to younger healthy elderly subjects. Moreover, both frontal theta responses and widespread delta responses were negatively correlated with age.b/ rb -0.44,N
doi:10.1016/j.ijpsycho.2016.07.515
487
Source localization in human information processing via hybrid functional magnetic resonance imaging and electroencephalography Hakki M. Karakasa, Sirel Karakasb
aHealth Sciences University Istanbul Fatih Sultan Mehmet Research
Hospital, Atasehir, Turkey
bDogus University Department Of Psychology, Istanbul, Turkey
Traditionally, psychophysiological correlates of information pro-cessing are obtained by using electroencephalography (EEG). This technique have revealed the temporal dimension of information processing without being able to provide more than coarse information on the localization of the underlying generators. As the cortical network of information processing is likely to exhibit a high spatial and temporal complexity, low spatial resolution inherent to the surface EEG is one of the major constraints for brain mapping needed in cognitive studies. Functional imaging is based on the well-establised interrelation between physiological function, energy metabolism and, and localized blood supply. In that context, advances in functional magnetic resonance imaging (fMRI) has made it possible to map brain activity in response to neural activation. Rapid progress in fMRI has increased our capability for visualizing working brain uncovering cerebral areas participating in the information processing. Integration attempt of above-mentioned techniques is one of the major topics of brain mapping. Prior anatomical and functional information from MRI may be used to regularize the EEG inverse problem, giving an improved solution with high spatial and temporal resolution. fMRI weightings provide the best compromise between separation of activity from correctly localized sources and minimization of error caused by missing sources. These attempts necessitate the similarity of EEG and fMRI activations in terms of spatial location. This requirement is fulfilled by simultaneous EEG and fMRI recordings (MRI-EEG) to establish the similar states of cognition and arousal. MRI-EEG to analyze the cognitive potentials of the brain is a major challenge in brain mapping. MRI-EEG may be able to detect high resolution electrophysiological activity while recording fMRI measures of the ongoing cortical activation to constraint the source localization. It may, therefore, provide an integrated data with high spatial resolution, in the range of millimeters (MRI), and a high temporal resolution, in the range of milliseconds (EEG). Extensive researches that were conducted in our MRI-EEG laboratory showed that event related potentials may be obtained under hostile MRI environ-ment and are comparable to the data obtained in our standard EEG-ERP laboratory. Ourfindings also show that the hybrid MRI-EEG technique can be used for a valid description of the spatiotemporal characteristics of ERP components. This hybrid technique, therefore, may significantly enhance the accuracy of source-localization procedures, enabling patterns of activation to be followed throughout the brain, a prerequisite for examining stages of information processing.
doi:10.1016/j.ijpsycho.2016.07.074
39
Symposium B3
Neurobiological correlates of empathy processing
Organizer: Josanne D.M. van Dongen (Netherlands), Ana Seara-Cardoso (United Kingdom), Agustín Ibañez (Argentina), Yawei Cheng (Taiwan), Jean Decety (United States)
