Room 255 BC

16:00 - 18:00

Moderators:

Galit Pelled, Robert Turner

John Robert Younce¹, Hsin-Yi Lai¹, and Yen-Yu Ian Shih^1
1Experimental Neuroimaging Laboraory, Department of Neurology and Biomedical Research Imaging Center, UNC Chapel Hill, Chapel Hill, NC, United States

This study demonstrates significant response in the motor cortex as a result of deep brain stimulation at the internal globus pallidus. The BOLD responses occur bilaterally in a frequency-dependent manner, with positive responses in the ipsilateral motor cortex peaking at high frequencies (100 Hz), and negative responses in the contralateral motor cortex peaking at low frequencies (40 Hz). These frequencies generally correspond to those producing improvement and exacerbation, respectively, of parkinsonian symptoms in humans and animal models, making this technique potentially powerful for exploration of cerebral changes in DBS in parkinsonian animal models.

Stephen Jones¹, Rafi Avitsian¹, Pallab K. Bhattacharyya¹, Juan Bulacio¹, Rei Enatsu¹, Jorge A. Gonzalez-Martinez¹, Dileep Nair¹, Imad Najm¹, Michael Phillips¹, and Myron Zhang^1
1Cleveland Clinic Foundation, Cleveland, OH, United States

We present the first study of simultaneous fMRI during direct electrical stimulation in the human brain of epilepsy patients. Spatial activation patterns and strengths in fMRI maps are compared to responses from electrical recordings from intracranial electrodes placed throughout the brain. We found significant positive correlation between strength of fMRI activation and electrical activity. Potential clinical applications include using electrically stimulated fMRI to plan for epilepsy surgery.

Rosa M. Sanchez Panchuelo¹, Rochelle Ackerley², Paul M. Glover¹, Bader Al Debasi¹, Richard W. Bowtell¹, Johan Wessberg², Susan T. Francis¹, and Francis McGlone^3
1Sir Peter Mansfield Magnetic Resonance Centre, University of Nottingham, Nottingham, United Kingdom, ²Physiology, University of Gothenburg, Göteborg, Sweden, ³Cognitive Neuroscience, Liverpool John Moores University, Liverpool, United Kingdom

We successfully performed microstimulation of single afferents in the environment of an ultra-high field (7T) MR scanner and collected high resolution fMRI data depicting the response to intraneural microstimulation. fMRI data were acquired for increasing current amplitudes during microstimulation of four different afferents in two subjects. Robust responses were found for all units, consistent with the activation pattern seen on applying vibrotactile stimulation to the receptive fields of the microstimulated units. Activation was not found for microstimulation at sub-sensation thresholds. High-resolution fMRI allowed the discrimination of the responses of microstimulation to single afferents located in the palm and middle finger.

Zhongming Liu¹, Jacco A. De Zwart¹, Catie Chang¹, Qi Duan¹, Peter van Gelderen¹, and Jeff H. Duyn^1
1Advanced MRI Section, Laboratory of Functional and Molecular Imaging, NINDS, National Institutes of Health, Bethesda, Maryland, United States

We propose a subspace method to analyze simultaneous EEG and fMRI at rest. It is based on the notion that the neuro-electrical activity underlying the fMRI signal may have EEG spectral features that report on regional neuronal dynamics and inter-regional interactions. We found characteristic spectral signatures in the EEG correlates of spontaneous fMRI signals at individual regions as well as the temporal correlation among regions. These spectral signatures not only allowed us to parcel the brain into clusters that resembled the established functional subdivisions, but also offered important clues for disentangling the involvement of individual regions in fMRI network activity.

Jeroen Cornelis Willem Siero^1,2, Dora Hermes^1,3, Hans Hoogduin², Peter R. Luijten², Natalia Petridou², and Nick F. Ramsey^1
1Rudolf Magnus Institute, University Medical Center Utrecht, Utrecht, Utrecht, Netherlands, ²Radiology, University Medical Center Utrecht, Utrecht, Utrecht, Netherlands, ³Stanford University, Stanford, California, United States

An often reported mismatch between expected and measured BOLD responses with increasing stimulus rates has led to the notion that neurovascular coupling is non-linear. We assess the neurovascular coupling of the sensorimotor cortex with a motor task by combining presurgical 7T BOLD fMRI and high density intracranial electrocorticography (ECoG) grids post-implant in the same subjects. With increasing movement rate the amplitude of both the BOLD and the ECoG broadband high frequency gamma response declined. The latter explained almost 80% of the apparent BOLD nonlinearity, indicating that in human sensorimotor cortex the BOLD response is tightly linked to neuronal activity.

Jennifer Marie Walz¹, Michael Carapezza¹, Bin Lou¹, Robin Goldman¹, Truman Brown², and Paul Sajda^1
1Biomedical Engineering, Columbia University, New York, NY, United States, ²Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, United States

We investigate the variability of the fMRI BOLD response related to natural waxing and waning of attention during a simple auditory target detection task. We use the prestimulus alpha power in simultaneously-acquired EEG as a measure of attention, and contrast the BOLD response for high vs. low attention trials. We show that when task-engagement wanes, recruitment of brain areas becomes limited, involving only the minimum areas required for the task.

Aneurin James Kennerley¹, Laurentius Huber², Toralf Mildner², John Edward Mayhew¹, Robert Turner³, Harald E. Möller², and Jason Berwick^1
1Faculty of Science, University of Sheffield, Sheffield, South Yorks., United Kingdom, ²Nuclear Magnetic Resonance Unit, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany, ³Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany

This in-vivo study quantifies a slice-selective-saturation (SSS) vascular space occupancy (VASO) fMRI sequence for measurement of Cerebral Blood Volume (CBV), at high field (7T). We compare SSS-VASO signal contrast with concurrent measurements of total hemoglobin (HbT) using 2-dimensional optical imaging spectroscopy (2D-OIS) in rat somatosensory cortex. VASO derived CBV changes are in good agreement in terms of both magnitude and temporal dynamics with HbT changes during both electrical stimulation and hypercapnic challenge. We observe 5-10% changes in CBV to stimulation in the rodent model - much lower than previously reported changes in human visual cortex (30-40%).

Xin Yu¹, Stephen Dodd², and Alan P. Koretsky^1
1NIH, Bethesda, MD, United States, ²National Institutes of Health, Bethesda, MD, United States

Channelrhodopsins (ChRs) were expressed along thalamocortical and cortiocortical pathways in the rat brain. An implanted fiber optic was targeted to axonal fibers that input neural activity into cortical areas. This experimental design allowed us to control projection activity in a fiber-specific manner and to detect reliable fMRI signals at relatively low light intensities in cortex remote from the fiber optic-penetrated brain areas. Light-driven fMRI signal can also be detected due to antidromic activity from back-propagated action potentials. This work demonstrated the usefulness of fMRI to detect brain activation via optogenetics of specific neural fiber pathways.

Christin Y. Sander^1,2, Jacob M. Hooker¹, Bruce R. Rosen^1,3, and Joseph B. Mandeville^1
1A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States, ²Electrical Engineering, Massachusetts General Hospital, Cambridge, MA, United States, ³Health Sciences and Technology, Harvard-MIT, Cambridge, MA, United States

In this study, we applied simultaneous PET/fMRI for the first time to directly relate fMRI signal to receptor occupancies in vivo. Using varying doses of a dopamine D2 antagonist in non-human primates, we showed that function (as measured by fMRI) is linearly related to occupancy (derived from PET), that dynamic time courses are matched between fMRI and PET and that we can obtain a measure of basal dopamine levels with the combined PET/fMRI measurement.

Hsiao-Ying Wey¹, Ciprian Catana², Jacob M. Hooker¹, Darin D. Dougherty^1,3, Gitte M. Knudsen⁴, Bruce R. Rosen¹, Randy L. Gollub^1,3, and Jian Kong^3
1Athinoula A. Martinos Center, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States, ²Athinoula A. Martinos Center, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, United States, ³Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States,⁴Neurobiology Research Unit, Rigshospitalet and University of Copenhagen, Copenhagen, DK-2100, Denmark

Simultaneous fMRI-PET provides unique advantage to relate neurochemical events (signaled by changes in selective receptor for binding) to neural activity (indexed by changes in BOLD signals). In this study, we present the first simultaneous fMRI-PET in human to investigate the engagement of opioid system during experimental pain, and how it compares to functional responses. Both fMRI and PET show great activation in response to pressure pain. fMRI reveals more activation than PET, including S1, SMA, and anterior cingulate. While PET and fMRI demonstrates many overlapping activations in the basal forebrain, such as the caudate/nucleus accumbens and thalamus. These areas are part of the pain descending control system responsible medicating pain through releasing endogenous opioid peptides.