New Approach Simultaneously Measures EEG and fMRI Connectomes. / Il nuovo approccio misura simultaneamente i connettomi EEG e fMRI.
New Approach Simultaneously Measures EEG and fMRI Connectomes. The procedure of the ENEA patent RM2012A000637 is very useful in this application. / Il nuovo approccio misura simultaneamente i connettomi EEG e fMRI. Il procediemtno del brevetto ENEA RM2012A000637 è molto utile in questa applicazione.
Segnalato dal Dott. Giuseppe Cotellessa / Reported by Dr. Giuseppe Cotellessa
New research demonstrates how two vastly different methods of measuring brain activity can provide meaningful data on brain networks simultaneously.
Functional magnetic resonance imaging and electroencephalography are used to provide information on very different aspects of neural communication between brain areas. fMRI captures very slow aspects of this communication based on neurons' energy expenditure, whereas EEG directly measures neurons' rapid communication in real time from the electrical signals of the brain. Researchers from the Beckman Institute for Advanced Science and Technology have developed a new approach to look at both types to measure brain communication simultaneously.
The study "Concurrent EEG- and fMRI-derived functional connectomes exhibit linked dynamics" was published in NeuroImage.
"Over the last two decades it has become more common to look at how different regions across the brain communicate rather than focusing on activation of individual regions. The connectome describes the entirety of connections across all the brain regions," said Sepideh Sadaghiani, an assistant professor of psychology at the University of Illinois at Urbana-Champaign, who leads the CONNECT Lab at the Beckman Institute. "Unfortunately, it has been hard to look at fMRI and EEG connectomes simultaneously."
EEG measures the electrical signals that are generated by neurons across the brain. However, the MRI scanners that are used for fMRI measurements interfere with the EEG signals because the scanners use magnetic fields that generate their own currents. As a result, artifacts are produced.
"We looked at how the fMRI connectome changes over time and whether those changes are accompanied by changes in electrophysiological connectomes, as measured by EEG," Sadaghiani said.
The researchers saw that even though fMRI-derived connectomes have been criticized in the past for noise issues, the changes in the connectome over time relate to actual changes in the neural activity, which were measured by EEG. Similarly, EEG-derived connectomes, previously criticized for spatially imprecise measurements of brain communication, are also meaningful in studying whole-brain connectomes because they correlate with the fMRI connectome changes.
"The correlation confirms that the shortcomings of both methods can be overcome and we can obtain meaningful data," Sadaghiani said.
The researchers are interested in improving the limitations of the two methods further. "fMRI is used to look at very specific regions of the brain that are a couple of millimeters in dimension. On the other hand, EEG signals can only look at large regions of the brain," Sadaghiani said. "If we need to compare connectomes obtained from both sets of data, we lose the spatial precision of fMRI. Conversely, EEG measures very rapid changes in connectomes whereas fMRI is inherently slow. Consequently, when comparing connectomes changes in EEG and fMRI we may lose the temporal resolution of EEG."
"This new finding that both modalities can reliably track changes of brain communication provides a solid foundation for future studies exploring human cognition and brain pathologies," said Jonathan Wirsich, a postdoctoral research associate in the CONNECT lab.
The researchers will conduct future studies at the Biomedical Imaging Center at Beckman to obtain higher quality data. Combined with new analytic approaches, they plan to compare the EEG and fMRI connectomes without losing the advantages of either method.
Functional magnetic resonance imaging and electroencephalography are used to provide information on very different aspects of neural communication between brain areas. fMRI captures very slow aspects of this communication based on neurons' energy expenditure, whereas EEG directly measures neurons' rapid communication in real time from the electrical signals of the brain. Researchers from the Beckman Institute for Advanced Science and Technology have developed a new approach to look at both types to measure brain communication simultaneously.
The study "Concurrent EEG- and fMRI-derived functional connectomes exhibit linked dynamics" was published in NeuroImage.
"Over the last two decades it has become more common to look at how different regions across the brain communicate rather than focusing on activation of individual regions. The connectome describes the entirety of connections across all the brain regions," said Sepideh Sadaghiani, an assistant professor of psychology at the University of Illinois at Urbana-Champaign, who leads the CONNECT Lab at the Beckman Institute. "Unfortunately, it has been hard to look at fMRI and EEG connectomes simultaneously."
EEG measures the electrical signals that are generated by neurons across the brain. However, the MRI scanners that are used for fMRI measurements interfere with the EEG signals because the scanners use magnetic fields that generate their own currents. As a result, artifacts are produced.
"We looked at how the fMRI connectome changes over time and whether those changes are accompanied by changes in electrophysiological connectomes, as measured by EEG," Sadaghiani said.
The researchers saw that even though fMRI-derived connectomes have been criticized in the past for noise issues, the changes in the connectome over time relate to actual changes in the neural activity, which were measured by EEG. Similarly, EEG-derived connectomes, previously criticized for spatially imprecise measurements of brain communication, are also meaningful in studying whole-brain connectomes because they correlate with the fMRI connectome changes.
"The correlation confirms that the shortcomings of both methods can be overcome and we can obtain meaningful data," Sadaghiani said.
The researchers are interested in improving the limitations of the two methods further. "fMRI is used to look at very specific regions of the brain that are a couple of millimeters in dimension. On the other hand, EEG signals can only look at large regions of the brain," Sadaghiani said. "If we need to compare connectomes obtained from both sets of data, we lose the spatial precision of fMRI. Conversely, EEG measures very rapid changes in connectomes whereas fMRI is inherently slow. Consequently, when comparing connectomes changes in EEG and fMRI we may lose the temporal resolution of EEG."
"This new finding that both modalities can reliably track changes of brain communication provides a solid foundation for future studies exploring human cognition and brain pathologies," said Jonathan Wirsich, a postdoctoral research associate in the CONNECT lab.
The researchers will conduct future studies at the Biomedical Imaging Center at Beckman to obtain higher quality data. Combined with new analytic approaches, they plan to compare the EEG and fMRI connectomes without losing the advantages of either method.
ITALIANO
Una nuova ricerca dimostra come due metodi molto diversi per misurare l'attività cerebrale possano fornire simultaneamente dati significativi sulle reti cerebrali.
La risonanza magnetica funzionale e l'elettroencefalografia sono utilizzate per fornire informazioni su aspetti molto diversi della comunicazione neurale tra le aree cerebrali. La risonanza magnetica acquisisce aspetti molto lenti di questa comunicazione in base al dispendio energetico dei neuroni, mentre l'EEG misura direttamente la rapida comunicazione dei neuroni in tempo reale dai segnali elettrici del cervello. I ricercatori del Beckman Institute for Advanced Science and Technology hanno sviluppato un nuovo approccio per esaminare entrambi i tipi per misurare contemporaneamente la comunicazione cerebrale.
Lo studio "I connomi funzionali simultanei derivati da EEG e fMRI mostrano dinamiche collegate" è stato pubblicato su NeuroImage.
"Negli ultimi due decenni è diventato più comune osservare come comunicano le diverse regioni del cervello piuttosto che concentrarsi sull'attivazione delle singole regioni. Il connome descrive l'insieme delle connessioni tra tutte le regioni del cervello", ha affermato Sepideh Sadaghiani, un assistente professore di psicologia all'Università dell'Illinois a Urbana-Champaign, che conduce il CONNECT Lab presso il Beckman Institute. "Sfortunatamente, è stato difficile guardare contemporaneamente i fomi RM e EEG."
L'ELETTROENCEFALOGRAMMA misura i segnali elettrici che sono generati dai neuroni attraverso il cervello. Tuttavia, gli scanner MRI utilizzati per le misurazioni fMRI interferiscono con i segnali EEG perché gli scanner utilizzano campi magnetici che generano le proprie correnti. Di conseguenza, vengono prodotti artefatti.
"Abbiamo esaminato come il connettoma fMRI cambia nel tempo e se questi cambiamenti sono accompagnati da cambiamenti nei connettomi elettrofisiologici, come misurato dall'ELETTROENCEFALOGRAMMA", ha detto Sadaghiani.
I ricercatori hanno visto che anche se i connomi derivati dalla fMRI sono stati criticati in passato per problemi di rumore, i cambiamenti nel connettoma nel tempo si riferiscono a cambiamenti effettivi nell'attività neuronale, che sono stati misurati dall'ELETTROENCEFALOGRAMMA. Allo stesso modo, i connettomi di derivazione EEG, precedentemente criticati per misurazioni spazialmente imprecise della comunicazione cerebrale, sono anche significativi nello studio dei connettomi del cervello intero perché correlati con i cambiamenti del connoma fMRI.
"La correlazione conferma che le carenze di entrambi i metodi possono essere superate e possiamo ottenere dati significativi", ha detto Sadaghiani.
I ricercatori sono interessati a migliorare ulteriormente i limiti dei due metodi. "La risonanza magnetica viene utilizzata per esaminare regioni molto specifiche del cervello che hanno una dimensione di un paio di millimetri. D'altra parte, i segnali EEG possono guardare solo a grandi regioni del cervello", ha detto Sadaghiani. "Se abbiamo bisogno di confrontare i connettomi ottenuti da entrambi gli insiemi di dati, perdiamo la precisione spaziale della fMRI. Al contrario, l'EEG misura cambiamenti molto rapidi nei connettomi mentre la fMRI è intrinsecamente lenta. Di conseguenza, confrontando i cambiamenti dei connettomi in ELETTROENCEFALOGRAMMA e fMRI possiamo perdere la risoluzione temporale di ELETTROENCEFALOGRAMMA. "
"Questa nuova scoperta secondo cui entrambe le modalità possono tracciare in modo affidabile i cambiamenti della comunicazione cerebrale fornisce una solida base per studi futuri che esplorano la cognizione umana e le patologie cerebrali", ha dichiarato Jonathan Wirsich, un ricercatore post-dottorato associato nel laboratorio CONNECT.
I ricercatori condurranno studi futuri presso il Centro di imaging biomedico di Beckman per ottenere dati di qualità superiore. Combinati con nuovi approcci analitici, hanno in programma di confrontare i connettomi EEG e fMRI senza perdere i vantaggi di entrambi i metodi.
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