S. Cugini

Publications of S. Cugini

• High-resolution spatio-temporal neuronal activation in the visual oddball task: a simultaneous EEG/fMRI study

  Authors: L. Marzetti, D. Mantini, S. Cugini, G.L. Romani, C. Del Gratta

  Noninvasive Functional Source Imaging of the Brain and Heart and the International Conference on Functional Biomedical Imaging, 2007. NFSI-ICFBI 2007. Joint Meeting of the 6th International Symposium on; 11/2007

  The combined use of EEG and fMRI allows for the fusion of electrophysiological and hemodynamic information in the study of human cognitive functions. In order to investigate cerebral activity duringThe combined use of EEG and fMRI allows for the fusion of electrophysiological and hemodynamic information in the study of human cognitive functions. In order to investigate cerebral activity during a visual oddball task, simultaneous EEG/fMRI recording from 10 healthy subjects was performed. A devoted data-analysis method based on trial-by-trial coupling of concurrent EEG and fMRI for the high-resolution spatio-temporal analysis of P300 neuronal activation was developed. Our results obtained from fMRI data showed the involvement of inferior and medial frontal gyrus, cingulated motor area, middle temporal gyrus, and inferior parietal lobule in the oddball task; furthermore, activations were generally right lateralized, in accordance with previous findings. Using the high temporal resolution of EEG, we could separate neuronal activations specifically related to P300 activity, and therefore study the activation timing. We found that the detection of rare targets, that is able to elicit the P300 component, stimulates a limbic-parietofrontal circuit, with latencies ranging between 300 and 400 ms. Our findings suggest that the proposed approach might be extended to other event-related experimental paradigms, and might represent an valuable tool for a clearer understanding of the cerebral mechanisms underlying a wide range of cognitive functions.

• Fusion of EEG and fMRI for the investigation of functional connectivity during a visual oddball task

  Authors: D. Mantini, S. Cugini, G.L. Romani, C. Del Gratta

  Noninvasive Functional Source Imaging of the Brain and Heart and the International Conference on Functional Biomedical Imaging, 2007. NFSI-ICFBI 2007. Joint Meeting of the 6th International Symposium on; 11/2007

  The combined use of EEG and fMRI allows the fusion of electrophysiological and hemodynamic information for the study of the human brain function. In order to investigate functional connectivityThe combined use of EEG and fMRI allows the fusion of electrophysiological and hemodynamic information for the study of the human brain function. In order to investigate functional connectivity during a visual oddball task, we performed simultaneous EEG/fMRI recording from 14 healthy subjects. A completely data-driven approach, based on trial-by-trial coupling of concurrent EEG and fMRI, was used for the retrieval of cerebral networks linked to P300. An ICA-based analysis of fMRI BOLD data allowed to characterize neuro-anatomically defined patterns, each of them with a definite spatial map and a specific time-course of activation. In addition, we performed single-trial analysis on EEG data, reconstructing the temporal evolution of the P300 amplitude. This time-course, convolved with a canonical HRF, was considered as an estimate of the P300-related activity in the BOLD signals, and allowed to identify two cerebral networks linked to target detection. They showed spatial maps already observed in previous studies, which could be respectively associated with the dorsal attention and the change-detection networks. Time-domain analysis of BOLD data suggested that the attention network might account for sustained activity reflecting amplitude modulations of P300, whereas the change-detection network for transient activity associated with the event-related P300 response.

• Complete artifact removal for EEG recorded during continuous fMRI using independent component analysis.

  Authors: D Mantini, M G Perrucci, S. Cugini, A Ferretti, G L Romani, C Del Gratta

  NeuroImage. 02/2007; 34(2):598-607.

  The simultaneous recording of EEG and fMRI is a promising method for combining the electrophysiological and hemodynamic information on cerebral dynamics. However, EEG recordings performed in the MRIThe simultaneous recording of EEG and fMRI is a promising method for combining the electrophysiological and hemodynamic information on cerebral dynamics. However, EEG recordings performed in the MRI scanner are contaminated by imaging, ballistocardiographic (BCG) and ocular artifacts. A number of processing techniques for the cancellation of fMRI environment disturbances exist: the most popular is averaged artifact subtraction (AAS), which performs well for the imaging artifact, but has some limitations in removing the BCG artifact, due to the variability in cardiac wave duration and shape; furthermore, no processing method to attenuate ocular artifact is currently used in EEG/fMRI, and contaminated epochs are simply rejected before signal analysis. In this work, we present a comprehensive method based on independent component analysis (ICA) for simultaneously removing BCG and ocular artifacts from the EEG recordings, as well as residual MRI contamination left by AAS. The ICA method has been tested on event-related potentials (ERPs) obtained from a visual oddball paradigm: it is very effective in attenuating artifacts in order to reconstruct clear brain signals from EEG acquired in the MRI scanner. It performs significantly better than the AAS method in removing the BCG artifact. Furthermore, since ocular artifacts can be completely suppressed, a larger number of trials is available for analysis. A comparison of ERPs inside the magnetic environment with those obtained out of the MRI scanner confirms that no systematic bias in the ERP waveform is produced by the ICA method.

• Complete artifact removal for EEG recorded during continuous fMRI using independent component analysis

  Authors: D. Mantini, M.G. Perrucci, S. Cugini, A. Ferretti, G.L. Romani, C. Del Gratta

  NeuroImage.

  The simultaneous recording of EEG and fMRI is a promising method for combining the electrophysiological and hemodynamic information on cerebral dynamics. However, EEG recordings performed in the MRIThe simultaneous recording of EEG and fMRI is a promising method for combining the electrophysiological and hemodynamic information on cerebral dynamics. However, EEG recordings performed in the MRI scanner are contaminated by imaging, ballistocardiographic (BCG) and ocular artifacts. A number of processing techniques for the cancellation of fMRI environment disturbances exist: the most popular is averaged artifact subtraction (AAS), which performs well for the imaging artifact, but has some limitations in removing the BCG artifact, due to the variability in cardiac wave duration and shape; furthermore, no processing method to attenuate ocular artifact is currently used in EEG/fMRI, and contaminated epochs are simply rejected before signal analysis. In this work, we present a comprehensive method based on independent component analysis (ICA) for simultaneously removing BCG and ocular artifacts from the EEG recordings, as well as residual MRI contamination left by AAS. The ICA method has been tested on event-related potentials (ERPs) obtained from a visual oddball paradigm: it is very effective in attenuating artifacts in order to reconstruct clear brain signals from EEG acquired in the MRI scanner. It performs significantly better than the AAS method in removing the BCG artifact. Furthermore, since ocular artifacts can be completely suppressed, a larger number of trials is available for analysis. A comparison of ERPs inside the magnetic environment with those obtained out of the MRI scanner confirms that no systematic bias in the ERP waveform is produced by the ICA method.