Yuki Hori1, Jun Ogura2, Naoki Ihara3, Tsunehisa Higashi4, Takayuki Tashiro4, Manabu Honda5, Takashi Hanakawa6. 1. Department of Advanced Neuroimaging, Integrative Brain Imaging Center, National Center of Neurology and Psychiatry, Kodaira, Tokyo, Japan; Department of Functional Brain Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Tokyo, Japan. Electronic address: horiy@ncnp.go.jp. 2. Department of Mental Disorder Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Tokyo, Japan. 3. Department of Advanced Neuroimaging, Integrative Brain Imaging Center, National Center of Neurology and Psychiatry, Kodaira, Tokyo, Japan; Department of Functional Brain Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Tokyo, Japan. 4. Department of Medical Engineering, LMS Co. Ltd., Bunkyo-ku, Tokyo, Japan. 5. Department of Functional Brain Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Tokyo, Japan. 6. Department of Advanced Neuroimaging, Integrative Brain Imaging Center, National Center of Neurology and Psychiatry, Kodaira, Tokyo, Japan; Department of Functional Brain Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Tokyo, Japan. Electronic address: hanakawa@ncnp.go.jp.
Abstract
BACKGROUND: In some behavioral neuroscience studies, an attachment is surgically fixed onto the head of an awake animal to allow the animal to perform learning tasks repeatedly in the same position in a task-training system. A recently developed task-training system enables operant conditioning of head-fixed rats within only a few days, and this system has been rigorously applied to record learning-associated neural activity using electrophysiological techniques. However, the head attachment of this device is made of metal and thus is not suitable for simultaneous brain imaging studies with X-ray computed tomography (CT), magnetic resonance imaging (MRI) or positron emission tomography (PET). NEW METHOD: We developed a novel head fixation device with a removable attachment to position the rat head precisely in both imaging and training devices across different sessions. The device consisted of a removable attachment, a clamp and a stage, all of which were made of PET/MRI compatible acrylic resin. We tested the usefulness of the device with (18)F-fluorodeoxyglucose (FDG) PET and CT. RESULTS: The new device did not substantially affect (18)F-FDG PET images. Repositioning of the rat's head across sessions and experimenters was at a level of submillimeter accuracy. COMPARISON WITH EXISTING METHOD: The errors of radioactivity concentration of (18)F-FDG in the PET image were lower with the present attachment than with the conventional metal attachment. Repositioning accuracy was considerably improved compared with a visual inspection method. CONCLUSIONS: The developed fixation device is useful for longitudinal behavioral and brain imaging studies in rats.
BACKGROUND: In some behavioral neuroscience studies, an attachment is surgically fixed onto the head of an awake animal to allow the animal to perform learning tasks repeatedly in the same position in a task-training system. A recently developed task-training system enables operant conditioning of head-fixed rats within only a few days, and this system has been rigorously applied to record learning-associated neural activity using electrophysiological techniques. However, the head attachment of this device is made of metal and thus is not suitable for simultaneous brain imaging studies with X-ray computed tomography (CT), magnetic resonance imaging (MRI) or positron emission tomography (PET). NEW METHOD: We developed a novel head fixation device with a removable attachment to position the rat head precisely in both imaging and training devices across different sessions. The device consisted of a removable attachment, a clamp and a stage, all of which were made of PET/MRI compatible acrylic resin. We tested the usefulness of the device with (18)F-fluorodeoxyglucose (FDG) PET and CT. RESULTS: The new device did not substantially affect (18)F-FDG PET images. Repositioning of the rat's head across sessions and experimenters was at a level of submillimeter accuracy. COMPARISON WITH EXISTING METHOD: The errors of radioactivity concentration of (18)F-FDG in the PET image were lower with the present attachment than with the conventional metal attachment. Repositioning accuracy was considerably improved compared with a visual inspection method. CONCLUSIONS: The developed fixation device is useful for longitudinal behavioral and brain imaging studies in rats.