title: Microelectrode mapping of tonotopic, laminar, and field-specific organization of thalamo-cortical pathway in rat.
abstract: The rat has long been considered an important model system for studying neural mechanisms of auditory perception and learning, and particularly mechanisms involving auditory thalamo-cortical processing. However, the functional topography of the auditory thalamus, or medial geniculate body (MGB) has not yet been fully characterized in the rat, and the anatomically-defined features of field-specific, layer-specific and tonotopic thalamo-cortical projections have never been confirmed electrophysiologically. In the present study, we have established a novel technique for recording simultaneously from a surface microelectrode array on the auditory cortex, and a depth electrode array across auditory cortical layers and within the MGB, and characterized the rat MGB and thalamo-cortical projections under isoflurane anesthesia. We revealed that the ventral division of the MGB (MGv) exhibited a low-high-low CF gradient and long-short-long latency gradient along the dorsolateral-to-ventromedial axis, suggesting that the rat MGv is divided into two subdivisions. We also demonstrated that microstimulation in the MGv elicited cortical activation in layer-specific, region-specific and tonotopically organized manners. To our knowledge, the present study has provided the first and most compelling electrophysiological confirmation of the anatomical organization of the primary thalamo-cortical pathway in the rat, setting the groundwork for further investigation.
authors.affiliation: Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan.
authors.forename: Tomoyo Isoguchi
authors.initials: TI
authors.lastname: Shiramatsu
authors.affiliation: Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan; Graduate School of Information Science and Technology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Kazusa
authors.initials: K
authors.lastname: Takahashi
authors.affiliation: Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Noda
authors.affiliation: Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan.
authors.forename: Ryohei
authors.initials: R
authors.lastname: Kanzaki
authors.affiliation: Teikyo University School of Medicine, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605, Japan.
authors.forename: Haruka
authors.initials: H
authors.lastname: Nakahara
authors.affiliation: Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan. Electronic address: takahashi@i.u-tokyo.ac.jp.
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Takahashi
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000200:Action Potentials; D000758:Anesthesia; D018685:Anesthetics, Inhalation / Q000494:pharmacology; D000818:Animals; D001303:Auditory Cortex / Q000502:physiology*; D001931:Brain Mapping / Q000295:instrumentation / Q000379:methods*; D004558:Electric Stimulation / Q000295:instrumentation / Q000379:methods; D004567:Electrodes, Implanted; D004867:Equipment Design; D005072:Evoked Potentials, Auditory; D005829:Geniculate Bodies / Q000502:physiology*; D007530:Isoflurane / Q000494:pharmacology; D008297:Male; D008839:Microelectrodes; D009434:Neural Pathways / Q000502:physiology; D009474:Neurons / Q000502:physiology; D017208:Rats, Wistar; D012815:Signal Processing, Computer-Assisted
chemical_list: D018685:Anesthetics, Inhalation; D007530:Isoflurane
keywords: auditory cortex; auditory thalamus; microelectrode array; thalamo-cortical system; tonotopic map