Biology subjects

Beuter, A.

Publications and source records attributed to Beuter, A..

3 recordsLinked to original sources

bioRxiv2023

Cortical Adaptation Mechanism in the Delta Band of Post-Stroke Aphasic subjects during Naming Task

AO_SCPLOWBSTRACTC_SCPLOWThis study explores differences in spatiotemporal cortical dynamics between five people with chronic post-stroke aphasia and five healthy subjects. Electroencephalography was recorded during picture naming in both groups. Frequency-specific Global Field Power (GFP) results showed that the delta band has higher power to discriminate between healthy subjects and people with aphasia (PWA) than theta and alpha bands. EEG topologies computed at the time of GFP peaks in the delta band revealed strong activation oscillating between posterior and anterior areas in PWA. On the other hand, EEG topologies from healthy subjects were variable. Then, Spatial ERP (S-ERP) were developed to add spatial resolution to classical ERP analysis. S-ERP and associated analyses confirmed the previously observed oscillatory pattern in the delta frequency band among PWA during picture naming. This oscillating pattern was alternating between occipital and prefrontal areas with almost opposite phases, a characteristic not observed in healthy subjects. In addition, all PWA performed well on the picture naming task, suggesting that this oscillating pattern may be a cortical adaptation mechanism enabling them to succeed. The observation of large-scale oscillating delta activity across the scalp in all post-stroke subjects who have substantially recovered from aphasia holds the potential to inspire innovative rehabilitation methods employing non-invasive brain stimulation techniques such as transcranial alternating current stimulation (tACS).

neuroscience↗

bioRxiv2023

Investigating Spatiotemporal Dynamics of Cortical Activity During Language Production in the Healthy and Lesioned Brain

Efficient language production requires rapid interactions between different brain areas. These interactions can be severely affected by brain lesions. However, the neurophysiological correlates of the spatiotemporal dynamics during language production are not well understood. The current pilot study explores differences in spatiotemporal cortical dynamics between five subjects with post-stroke aphasia and five control subjects. Electroencephalography was recorded during picture naming in both groups. Average-based analyses (event-related potential (ERP), frequency-specific Global Field Power (GFP)), reveal a strong synchronization of cortical oscillations, especially within the first 600ms post-stimulus, with a time shift between participants with aphasia and control subjects. ERPs and the corresponding brain microstates indicate coordinated brain activity alternating mainly between frontal and occipital zones. This behavior can be described as standing waves between two main sources. At the single-trial scale, traveling waves (TW) were identified from both phase and amplitude analyses. The spatiotemporal distribution of amplitude TW reveals subject-specific organization of several interconnected hubs. In patients with aphasia this spatial organization of TW reveals zones with no TW notably in the vicinity of stroke lesions. The present results provide important hints for the hypothesis that TW contribute to the synchronization and communication between different brain areas especially by interconnecting cortical hubs. Moreover, our findings show that cortical dynamics is affected by brain lesions. Contribution to the FieldO_LISpatiotemporal cortical dynamics of individual trials reveals the presence of phase and amplitude traveling waves. C_LIO_LIExploration of traveling waves on the 2D cortical surface reveals the presence of interconnected epicenters or hubs in all subjects. C_LIO_LIThe spatiotemporal distribution of traveling waves shows a higher density in the prefrontal area for people with aphasia than for healthy subjects. C_LIO_LIFor subjects with aphasia, a sparser density of traveling waves is observed in the approximated lesion area. C_LIO_LIEvent-related potential analyses reveal a consistent alternating activity between the frontal and occipital regions. C_LIO_LISubjects with aphasia present a larger and/or delayed contribution in the delta range in the GFP patterns compared to control subjects. C_LI

neuroscience↗

bioRxiv2022

Characterization of spatiotemporal dynamics in EEG data during picture naming with optical flow patterns

We present an analysis of the spatiotemporal dynamics of the oscillations in the electric potential that arises from neural activity. Depending on the frequency and phase of oscillations, these dynamics can be characterized as standing waves or as out-of-phase and modulated waves, which represent a combination of standing and moving waves. We characterize these dynamics as optical flow patterns, in terms of sources, sinks, spirals and saddles. Analytical and numerical solutions are compared with real EEG data acquired during a picture-naming task. Analytical approximation of standing waves allows us to establish some properties of pattern location and number. Namely, sources and sinks have mainly the same location, while saddles are located between them. The number of saddles correlates with the sum of all the other patterns. These properties are confirmed in both the simulated and real EEG data.

neuroscience↗