Jorge J Riera, Ph.D.
Department of Biomedical Engineering
Florida International University
10555 W. Flagler Street EAS 2673
Miami, FL 33174
Biophysical Foundations of Neuroimaging in Normal Aging and Brain Disorders
Brain imaging constitutes a powerful tool to study brain functions in both healthy individuals and patients with a variety of brain disorders. The temporal resolution achieved at the present by different modalities allows us to study brain processes occurring from milliseconds to even days. Although much progress has been made, the biophysical foundations of brain imaging are still elusive. In order to identify the fundamental mechanisms underlying the genesis of brain imaging data from a microscopic approach, an intermediate physical level, the mesoscale, needs to be properly described and modeled (Fig. 1). Interpreting a variety of neuroimaging modalities (e.g. EEG/MEG, fMRI, PET/SPECT) at the mesoscopic level from a fundamental neuroscience perspective has been one of the long-term scientific goals in Dr. Riera’s career. In three recent reviews (J Integrative Neuroscience, 5(2), 273-326, 2006; NeuroImage 40, 1436-1459, 2008; Current Opinion in Neurology, 23(4), 374-381, 2010), he has discussed the physiological, biochemical and physical working principles at the mesoscopic level in the cerebral cortex with the strongest impact on the genesis of brain imaging.
At FIU, Dr. Riera performs invasive experiments on rodents, as well as non-invasive studies in humans. The latter are in collaboration with other researchers inside/outside FIU. The animal experiments carried out in Dr. Riera’s group are based on the combinations of pharmacological manipulations (i.e. agonist/antagonist agents) and four main recording techniques (i.e. intracranial electrical potentials obtained with microelectrode arrays, large-scale EEG data, laser Doppler flowmetry and O2/NO amperometric measurements). Through pharmacological manipulations, his group aims to isolate crucial pathways within the neurovascular coupling route and to enhance the activity of particular cortical microcircuit networks both in normal rodents and in those used to model pathological situations. Of particular interest are dementias, epilepsy, hypertension and the cerebro-vascular trauma.
Riera J., Ogawa T., Goto T., Sumiyoshi A., Nonaka H., Evans A., Miyakawa H., Kawashima R. Pitfalls in the dipolar model for the neocortical EEG sources. Journal of Neurophysiology, in press, 2012.
Sumiyoshi, A., Riera J., Ogawa T., Kawashima R. A Mini-Cap for simultaneous EEG and fMRI recording in rodents. NeuroImage 54, 1951-1965, 2011.
Riera J., Hatanaka R., Uchida T., Ozaki T., Kawashima R. Quantifying the uncertainty of spontaneous Ca2+ oscillations in astrocytes: Particulars of Alzheimer’s disease. Biophysical Journal, 101(3), 554-564, 2011.
Ogawa T., Riera J., Goto T., Sumiyoshi A., Nonaka H., Jerbi K., Bertrand O., Kawashima R. Dissimilar schemes for a sparse and heterogeneous codification of sound attributes in the primary auditory cortex of rats. The Journal of Neuroscience 31(41):14639-14653, 2011.
Riera J., Hatanaka R., Ozaki T., and Kawashima R. Modeling the spontaneous Ca2+ oscillations in astrocytes: Inconsistencies and usefulness. Journal of Integrative Neuroscience 10:439-473, 2011.
Riera J., Ogawa T., Hatanaka R., Goto T., Sumiyoshi A., Enjieu Kadji H., Nakauchi S., Kawashima R. Concurrent observations of astrocytic Ca2+ activity and multisite extracellular potentials from an intact cerebral cortex. J. Biophotonics 3, 3, 147-160, 2010.
Riera J., Sumiyoshi A. Brain oscillations: Ideal scenery to understand the neurovascular coupling. Current Opinion in Neurology 23(4), 374-381, 2010. (Review)
Goto T., Hatanaka R., Ogawa T., Sumiyoshi A., Riera J., Kawashima R. An evaluation of the conductivity profile in the barrel cortex of Wistar rats. Journal of Neurophysiology 104, 3388-3412, 2010.
Riera J., Jimenez J.C., Wan X., Kawashima R., Ozaki T. Nonlinear local electro-vascular coupling. Part II: From data to neural masses. Human Brain Mapping, 28, 335-354, 2007.
Riera J., Valdés P.A., Tanabe K., Kawashima R. A theoretical formulation of the electrophysiological inverse problem: The spherical head model. Physics in Medicine and Biology, 51, 1737-1758, 2006.
Riera J., Aubert E., Iwata K., Kawashima R., Wan X., Ozaki T. Fusing EEG and fMRI based on a bottom-up model: Inferring activation and effective connectivity in neural masses. Phil. Trans. R. Soc. Lond. B., 360, 1457, 1025-1041, 2005.
Riera J., Watanabe J., Kazuki I., Naoki M., Aubert E., Ozaki T., Kawashima R. A state-space model of the hemodynamic approach: Non-linear filtering of BOLD signals. NeuroImage, 21, 2, 547-567, 2004.
Riera J., Bosch J., Yamashita O., Kawashima R., Sadato N., Okada T., Ozaki T. fMRI activation maps based on the NN-ARx model. NeuroImage, 23, 2, 680-697, 2004.