Daniel Albaugh¹, Garret Stuber², and Yen-Yu Ian Shih^3
1Curriculum in Neurobiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States, ²Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States, ³BRIC, Department of Neurology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States

Neurovascular coupling represents a central tenet of functional MRI research. However, in the rodent striatum, the directionality of vascular responses to neural activity is not always clear. Here, we employ optogenetic-fMRI to uncover two striatal circuit mechanisms of activity-induced vasoconstriction.

Jack A Wells¹, Isabel N Christie¹, Sergey Kasparov², Alexander Gourine³, and Mark F Lythgoe^1
1Centre for Advanced Biomedical Imaging, University College London, London, London, United Kingdom, ²Department of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom, ³Neuroscience, Physiology & Pharmacology, University College London, London, United Kingdom

Despite the widespread application of fMRI, questions remain regarding the link between the measured BOLD signal and the underlying changes in neural activity. Here, we present a novel technique to investigate spatial correlations of neurovascular coupling. We use a single pulse of light (10ms) to modulate the volume of optogenetically induced action potentials in the rat cortex with concurrent fMRI. A directly proportional relationship was observed between the volume of BOLD response and the estimated volume of light-activated brain tissue, a finding which has possible implications for the design of future fMRI studies.

Russell W. Chan^1,2, Alex T.L. Leong^1,2, Joe S. Cheng^1,2, Partick P. Gao^1,2, Shu-Juan J. Fan^1,2, Kevin K. Tsia², and Ed X. Wu^1,2
1Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong, China, ²Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong, China

Previous studies suggested that the intrahippocampal interactions may be governed by gamma oscillations, while hippocampal-cortical interactions might be directed by low frequency oscillation and/or sharp wave-ripple. However, exactly how different frequency contributes to large-scale intrahippocampal and hippocampal-cortical interactions remains largely unknown. In this study, optogenetic functional MRI was applied to investigate the frequency-dependent hippocampal network activity. Large-scale hippocampal and cortical activations were found during 40Hz and 1Hz stimulation, respectively. This is also the first study demonstrating large-scale and widespread hippocampal-cortical activity by driving CaMKIIa-positive cells in the dorsal hippocampus. This widespread hippocampal-cortical activity suggests that the generation of low frequency oscillation in the dorsal hippocampus can modulate cortical activity.

Zhifeng Liang^1,2, Glenn D.R. Waston^2,3, Kevin D. Alloway^2,3, Gangchea Lee¹, Thomas Neuberger¹, and Nanyin Zhang^1,2
1Dept. of Biomedical Engineering, Pennsylvania State University, University Park, PA, United States, ²Center for Neural Engineering, The Huck Institutes of Life Sciences, Pennsylvania State University, University Park, PA, United States, ³Neural and Behavioral Sciences, College of Medicine, Pennsylvania State University, Hershey, PA, United States

Medial prefrontal cortex (mPFC) plays a critical role in cognition and emotion. However, mPFC functional networks cross the whole brain remains elusive, particularly in awake rodents. Here we combined optogenetics and functional magnetic resonance imaging (opto-fMRI) to reveal mPFC functional networks in awake rodents. We found optogenetic stimulations in infralimbic cortex (IL, part of mPFC) generated robust, reliable and distributed activations in awake rats, which resembled efferent anatomical projections of IL. The results expanded the applicability of opto-fMRI from sensorimotor to cognition-related networks in awake rodents, which can be utilized to investigate circuit-level mechanisms underlying mPFC-related brain functions and behaviors.

Alex T.L. Leong^1,2, Russell W. Chan^1,2, Patrick P. Gao^1,2, Joe S. Cheng^1,2, Jevin W. Zhang^1,2, Shu-Juan J. Fan^1,2, Kevin K. Tsia², Kenneth K.Y. Wong², and Ed X. Wu^1,2
1Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong, SAR, China, ²Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong, SAR, China

Timing has been postulated as one of the most important aspects of information processing in the brain, and frequency is the most intuitive of the many timing parameters. Thalamocortical circuits present a good opportunity to comprehend the importance of timing due to their well-known relay pathways to the cortex in all sensory modalities. They have oscillations that are well characterized through multisite electrical recordings during wakefulness, sleep, anesthesia and task-driven activity. The advent of optogenetics coupled with fMRI enables an unprecedented opportunity to probe the dynamics of the somatosensory thalamocortical circuit of the rat in response to differing frequency stimulation.

Rosa Maria Sanchez Panchuelo¹, Rochelle Ackerley², Paul Glover¹, Richard Bowtell¹, Francis McGlone³, Johan Wessberg², and Susan Francis^1
1University of Nottingham, Nottingham, United Kingdom, ²University of Gothenburg, Gothenburg, Sweden, ³Liverpool Johns Moore 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 (INMS). fMRI data were acquired during INMS of 11 different afferents across four subjects. We compare the cortical responses elicited by INMS of single afferents with those produced by mechanical stimulation of each afferent’s receptive field. We show that INMS and vibrotactile stimulation engage sensory related brain areas, and that INMS activates additional brain networks. INMS responses were localized within the expected area of digit representation in primary somatosensory cortex.

Basavaraju G Sanganahalli¹, Michelle R Rebello², Peter Herman¹, Gordon M Shepherd³, Justus V Verhagen^2,4, and Fahmeed Hyder^1,5
1Diagnostic Radiology, Yale University, New Haven, CT, United States, ²The John B. Pierce Laboratory, Yale University, New Haven, CT, United States,³Neurobiology, Yale University, New Haven, CT, United States, ⁴Neurobiology, Yale University, CT, United States, ⁵Biomedical Engineering, Yale University, New Haven, CT, United States

To improve functional understanding of odor-evoked glomerular activity patterns revealed by BOLD signal and to relate how input activities of glomeruli reflected by calcium imaging relate to bulk neuropil activity of fMRI, we designed a study to image the same rats with fMRI first and then with calcium imaging. Excellent correspondence between odor-evoked fMRI maps and calcium-sensitive dye imaging patterns of input activity suggests input activity is a dominant part of neuropilar activity in glomeruli. In conclusion, multi-modal functional imaging of rat olfactory bulb with odorant stimulation provides new opportunities for gaining insights into complexities of neuropilar activities.

Markus Weichenberger¹, Rüdiger Brühl², Martin Bauer², Robert Kühler², Albrecht Ihlenfeld², Johannes Hensel², Christian Koch², Bernd Ittermann², Simone Kühn¹, and Tilmann Sander^2
1Max Planck Institute for Human Development, Berlin, Germany, ²Physikalisch-Technische Bundesanstalt (PTB), Braunschweig und Berlin, Germany

Infrasound is a potential hazard to human health. This multimodal study is targeting the perception of infrasound and low-frequency sound in humans. Sinusoidal acoustic stimuli of seven frequencies (8, 12, 20 , 40, 63, 125, 250 Hz) were individually calibrated for 15 volunteers and applied while conducting a MEG and fMRI study. Location and amplitude of the activated brain area were analyzed for both modalities showing different frequency dependencies. Although the reception of the infrasound is mainly tactile only brain activation in the region of the auditorial cortex was found.

F. Molaei-Vaneghi^1,2, Jonas Bause¹, Philipp Ehses¹, Klaus Scheffler¹, and Andreas Bartels^2
1High Field Magnetic Resonance, Max-Planck Institute for Biological Cybernetics, Tübingen, Baden-Württemberg, Germany, ²Center for Integrative Neuroscience (CIN), Vision and Cognition Lab, Tübingen, Baden-Württemberg, Germany

Here we propose to use ultra-high-field (9.4T) human fMRI in order to answer two questions: firstly, is there a differential involvement of cortical layers in the processing of retinal motion and of objective motion in high-level visual areas? Second: is there a columnar organisation segregating retinal and objective motion processing? A differential laminar response profile to the two motion types would provide important cues with regards to the hierarchy of processing involved in different areas, with modulation of upper, middle, or lower layers speaking for feedback, bottom-up or output sources of the different signals, respectively. A columnar segregation would indicate specialized and segregated circuits within a given area.

Mark Mikkelsen¹, C. John Evans¹, Alan J. Stone^1,2, Esther A. H. Warnert¹, and Krish D. Singh^1
1CUBRIC, School of Psychology, Cardiff University, Cardiff, United Kingdom, ²FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom