Jaakko Paasonen¹, Petteri Stenroos^1,2, Hanne Laakso¹, Tiina Pirttimäki¹, Ekaterina Zhurakovskaya¹, Raimo A Salo¹, Heikki Tanila¹, Djaudat Idiyatullin³, Michael Garwood³, Shalom Michaeli³, Silvia Mangia³, and Olli Gröhn^1
1A.I.V. Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland, ²Grenoble Institut des Neurosciences, Grenoble, France, ³Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States

Currently there are no tools to study simultaneously whole-brain processing and behavior in rats. Here we introduce a novel approach for fMRI studies in head-fixed and minimally restrained rats that can express behavior. This was achieved with MB-SWIFT sequence that is both quiet and insensitive to movement. First, the whole brain, including hindbrain, was functionally parcellated with high fidelity. Second, fMRI maps showing activation in relevant networks during spontaneous single behavioral events were successfully generated. Our approach links global network activity to behavior and has potential to enable novel experimental designs in neuroscience studies.

Denis Le Bihan¹, Luisa Ciobanu¹, Yukiko Masaki^1,2, and Erwan Selingue^1
1NeuroSpin, Gif-sur-Yvette, France, ²Shionogi & Co., Ltd., Osaka, Japan

BOLD and diffusion fMRI signal response time courses following rat visual stimulation differ in time, amplitude and shape.

Davide Boido¹, Ali-Kémal Aydin², Yannick Goulam Houssen², Demené Charlie³, Mickael Tanter³, Serge Charpak², and Luisa Ciobanu^1
1NeuroSpin, CEA, Paris, France, ²Inserm - Institut de la Vision, Paris, France, ³Physics for Medicine, ESPCI, INSERM, CNRS, PSL Research University, Paris, France

Using UHF (17.2T) BOLD fMRI on the mouse Olfactory Bulb (OB) we recorded odor activation at high spatio-temporal resolution (0.17x0.17x0.3 mm; TR= 250ms). With 6% 1s odor application we found fast unimodal activations. Increasing odor concentration and duration (35% 5s) we revealed the second vascular component.  Adding functional ultrasound (fUS) recordings from the co-registered OB coronal section, we could verify an overall good accordance in the dynamics of BOLD and fUS signals in small ROIs (< 0.5 mm^3), although evident differences were also found in some ROIs. We aim at highlighting the relationship between local vascular activity and BOLD fMRI.

Won Beom Jung¹, Geun Ho Im¹, Haiyan Jiang^1,2, and Seong-Gi Kim^1,2
1Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon, Korea, Republic of, ²Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Korea, Republic of

To further advance understanding of brain functions, identifying the direction of information flow, such as thalamocortical vs. corticothalamic projections, is critical. Because the early hemodynamic response at microvessels near active neurons can be detected by ultrahigh field fMRI, we propose using the onset times of fMRI responses to discern the information flow. This approach was confirmed by observing the high temporal resolution BOLD fMRI responses to bottom-up somatosensory stimulation and top-down optogenetic stimulation of the primary motor cortex in anesthetized mice at ultrahigh field of 15.2 T.

Shinho Cho¹, Arani Roy², Chao Liu², Djaudat Idiyatullin¹, Wei Zhu¹, Yi Zhang¹, Xiao-Hong Zhu¹, Prakash Kara², Wei Chen¹, and Kâmil Uğurbil^1
1Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota, Minneapolis, MN, United States, ²Center for Magnetic Resonance Research and Department of Neuroscience, University of Minnesota, Minneapolis, MN, United States

Using high isotropic resolution (250 μm), cerebral blood volume weighted (wCBV) fMRI, we examined whether layer-specific cortical signals could be detected upon visual stimulation in cat primary visual cortex. We also examined single blood vessel responses (dilation, blood flow) to identical stimuli by using 2- and 3-photon imaging in the same cortical area and species. With fMRI, we often found orientation preference maps tangential and orthogonal to the cortical surface. Moreover, the laminar profile of orientation selectivity with both imaging techniques (fMRI and optical) revealed a selectivity index that was significantly lower in cortical layer 4 compared to layer 2/3.

Sangcheon Choi^1,2, Yi Chen¹, Hang Zeng^1,2, and Xin Yu^1,3
1Max Planck Institute for Biological Cybernetics, Tuebingen, Germany, ²Graduate Training Centre of Neuroscience, Tuebingen, Germany, ³MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Harvard Medical School, Massachusetts General Hospital, Charlestown, MA, United States

We developed a bilateral line-scanning fMRI method to investigate interhemispheric slow fluctuations (< 0.1 Hz) with laminar specificity in resting-state fMRI in anesthetized rats. Based on the coherence analysis, two distinct slow fluctuation features in symmetric cortices were identified: ultra-slow fluctuation (0.01-0.02 Hz) was synchronized across all cortical laminae, and Layer 2/3 specific slow fluctuations (0.08-0.1 Hz). In contrast to the ultra-slow fluctuation related to global brain state changes, the Layer 2/3 specific slow fluctuation is more likely associated with intrinsic neuronal correlation driven by the callosal projection.

Augix Guohua Xu¹, Sunhang Shi¹, Yunyun Rui¹, Xiaotong Zhang¹, Lizabeth Romanski², Katalin M. Gothard³, and Anna Wang Roe^1
1Interdisciplinary Institute of Neuroscience and Technology, Zhejiang University, Hangzhou, China, ²Dept of Neuroscience, University of Rochester School of Medicine, Rochester, NY, United States, ³University of Arizona, Dept of Physiology, Tucson, AZ, United States

We have previously shown that INS-fMRI is a rapid method for mapping mesoscale brain networks in the macaque monkey brain. Here, we extend this capability by stimulating deep brain sites. We test this new method by stimulating the basal nucleus of amygdala in the macaque monkey. The connections we identified are consistent with dye-tracing studies. In conclusion, our results indicate that INS-fMRI is a promising novel method for mapping connections of deep brain structures at high spatial resolution.

Rita Gil¹, Mafalda Valente¹, Alfonso Renart¹, and Noam Shemesh^1
1Champalimaud Centre for the Unknown, Lisbon, Portugal

The underlying source of negative BOLD responses (NBRs) is still debated. Here, we show that binocular visual stimulation with short inter-stimulus-intervals (ISIs) lead to strong NBRs in the rat superior colliculus (SC). We perturbed cortical feedback loops with V1 ibotenic acid lesions and input to the ipsilateral SC via tectotectal projections through monocular stimulation. SC NBRs were upward regulated upon both V1 lesioning and monocular stimulation of non-lesioned animals. When combining reduced cortical feedback and tectotectal projections, NBRs in SC were abolished. Our results suggest an important role for corticotectal and commissural tectotectal projections in SC NBRs at short ISIs.

Vahid Khalilzad Sharghi¹, Eric Maltbie¹, Wen-Ju Pan¹, Shella Keilholz¹, and Kaundinya Gopinath^2
1Biomedical Engineering, Emory University/Georgia Institute of Technology, Atlanta, GA, United States, ²Department of Radiology & Imaging Sciences, Emory University, Atlanta, GA, United States

In this study, we tested hypothesis advanced by some groups that brain slow rhythms serve as the neurophysiological basis of resting state fMRI (rsfMRI). Putative suppression of cortical rhythms with an established technique, led to significant reduction in the amplitude of rsfMRI quasi-periodic patterns (QPPs), and enhancement in the rsfMRI measures of intrinsic functional connectivity FC in canonical brain function networks in rats. The results indicate cortical slow rhythms serve as the genesis of only the vigilance dependent components (e.g., QPP) of rsfMRI signals. Further attenuation of these non-specific signals enhances delineation of brain function networks.

Eddie C. Wong^1,2, Xunda Wang^1,2, Vick Lau^1,2, Alex T.L. Leong^1,2, 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

Audition is vital for communication, learning and memory processes. However, the hippocampus, which can support these functions, is absent from networks of auditory processing. To bridge this gap, we employed auditory fMRI and pharmacological inactivation techniques to directly characterize how hippocampal outputs affect auditory responses to auditory stimuli in primary auditory-associated structures. Using behaviorally-relevant, natural sounds for rodent behaviors, or their temporally-reversed counterparts, we revealed that absence of hippocampal output disrupts auditory responses to vocalizations in auditory midbrain, thalamus and cortex. For the first time, our results demonstrated the critical role of hippocampus in shaping response selectivity to behaviorally-relevant sounds.