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The application of pharmacological MRI in manganese enhancement of brain
Abstracts / Neuroscience Research 58S (2007) S1–S244
S129
P1-k26 Pre-surgical mapping of the brain with brain tumor
P1-k29 The application of pharmacological MRI in manganese
Takashi Nihashi 1 , Shigenori Takebayashi 2,3 , Masahiko Bundo 2 , Masazumi Fujii 3 , Toshihiko Wakabayashi 3 , Jun Yoshida 3 , Hiroyuki Fujisawa 1 , Hitomi Shimizu 1 , Kazumasa Hayasaka 1 , Shinji Naganawa 4 1 Department of Radiology, National Hospital for Geriatric Medicine, Obu, Japan; 2 Department of Neurosurgery, National Hospital for Geriatric Medicine, Japan; 3 Department of Neurosurgery, Nagoya University Graduate School of Medicine, Japan; 4 Department of Radiology, Nagoya University Graduate School of Medicine, Japan
enhancement of brain
To determine the location of central sulcus (CS) and dominant hemisphere of the language is important for presurgical mapping. We use fMRI for the patient who needs a surgery. We considered the efficacy of fMRI in our institute, retrospectively. Fifty-five patients were examined. We use five tasks, that is, tactile stimulation to bilateral palm, finger tapping, verb generation, news listening, picture naming and select suitable tasks with the clinical condition and the location with brain tumor. CS could be identified 96 and 85%, representatively by tactile stimulation and finger tapping in the affected hemisphere. The laterality of dominant hemisphere of language could be identified 78, 59, 58% by verb generation, news listening, picture naming, representatively.
P1-k27 Nonlinear local neurovascular coupling in the cerebral cortex
Jorge J. Riera 1 , Juan C. Jimenez 2 , Tohru Ozaki 3 , Ryuta Kawashima 1 , Xiaohong Wan 4 1 IDAC, Tohoku University, Sendai, Japan; 2 Institute of Cyber, Math and Physics, Havana, Cuba; 3 The Institute of Stat Math, Tokyo, Japan; 4 RIKEN Brain Science Institute, Wako, Japan We will present a biophysical model of how electrical and hemodynamic brain signals could be generated within a cortical microcolumn. The model has three components. The first is the neural mass model of three neuronal populations that responds to incoming excitatory inputs. The second and third components model the generation of measured electrical and hemodynamic meso-states, respectively. We reformulate the model in the context of the continuous-discrete state space theory in order to make inferences about the unknown parameters and the unobservable states (i.e. membrane potentials, ionic currents, NO, flow-inducing signal, CBF, CBV, dHb) from the local linearization filter and the innovation approach. Inference on this model is performed from concurrent EEG/fMRI signals obtained during a visual experiment in which a subject observes a radial checkerboard with pattern reversal at 4 Hz. JST/RISTEX; R&D promotion scheme (TAO); 21st Century Center of Excellence (COE) Program; Management Expenses Grants of Tohoku University.
P1-k28
Suppression of neural activity and hemodynamic responses during hypercapnic challenges in rats
Masahito Nemoto, Yoko Hoshi, Chie Sato Tokyo Institute of Psychiatry, Tokyo, Japan To investigate the effect of hypercapnia on the neural and hemodynamic responses, we measured electrophysiological signals (local field potentials, LFP < 100 Hz; multiunit activity, MUA > 300 Hz), optical intrinsic signals (586 and 605 nm, indicators of CBV and oxygenation) and spectral changes in reflected light. Rats were anesthetized with ␣-chloralose and artificially ventilated with muscle relaxants. Hypercapnic challenge was performed by 10% CO2 inhalation. We recorded these signals while delivering 2 s electrical pulses to the hindpaw. We observed that hemodynamic responses (CBF, CBV) were suppressed more strongly than neural responses (LFP, MUA), and prolonged deoxyhemoglobin increases in the early phase with attenuation of deoxyhemoglobin decreases in the late phase (i.e., disruption of hyperoxygenation responses). These results suggested that transfer functions from neural to hemodynamic responses may be different between normo- and hypercapnia, and imaging of early dip optical signals and positive BOLD fMRI signals may not accurately reflect neural responses during respiratory depression.
Kouichi Itoh 1 , Hirotada Fujii 2 Laboratory of Molecular Pharmacology, Tokushima Bunri University, Sanuki, Kagawa, Japan; 2 School of Health Science, Sapporo Medical University, Sapporo, Hokkaido, Japan
1
Manganese (Mn)-enhanced MRI (MEMRI) studies have been carried out extensively to visualize brain in vivo. In this paper, we observed much lower contrast enhancement in MEMRI in rats anesthetized with ketamine, compared with other anesthetics (urethane, pentobarbital, isoflurane). Ketamine is well known to be the noncompetitive antagonist for the NMDA receptors (NMDAR). Therefore, the contrast enhancement in MEMRI might be activity-dependently controlled by the NMDAR. To confirm these effects, the effects of both NMDAR and AMPAR antagonists, MK-801, and NBQX, respectively, on MEMRI were examined. When rats were treated with MK-801 remarkably inhibited the signal enhancement by Mn2+ as well as ketamine. In contrast, treatment of rats with NBQX failed to inhibit the enhancement of the signal intensity in MEMRI. These MEMRI results suggest that the signal enhancement in MEMRI in rat brains is affected by NMDAR, but not AMPAR. Research funds: a Grant-in-aid for KAKEN (15390363) and Edu and Collabo Res of Tokushima Bunri University
1 Actin-dependent regulation of Shank1 dynamics in P2-a0 Purkinje cell dendrites Toshimitsu Fuse, Haruhiko Bito Department of Biochemistry and 21st Century COE Program, University of Tokyo, Tokyo, Japan Purkinje cell dendrites possess the highest number of spines among CNS neurons. Though critical in cerebellar circuit formation, the molecular mechanisms underlying the formation and functional maturation of Purkinje cell spines are yet poorly understood. Ongoing studies suggest the existence of a tight control mechanism by which actin can efficiently accumulate in Purkinje cell spines. To gain further insights on the role of actin cytoskeleton in the organization of protein assembly at the postsynaptic density (PSD) of Purkinje cells, we studied the distribution and the redistribution of several PSD molecules present in the Purkinje cell spines upon treatment with various actin cytoskeleton-modifying reagents. Interestingly, coincidence of actin depolymerization with a prolonged 55 mM KCl depolarizing stimulation caused a robust mobilization of a key PSD scaffold molecule, Shank1, from the synapses to the dendritic shaft. Thus, neuronal activity and actin cytoskeletal reorganization may critically regulate Purkinje cell PSD assembly via control of Shank dynamics. Research fund: KAKENHI 17023010
2 Existence of specific binding sites for Cbln1 in the hipP2-a0 pocampus Tetsuro Kondo 1,2 , Takatoshi Iijima 1 , Yuichi Kamekawa 1 , Keiko Matsuda 1 , Aya Ishida 1 , Michisuke Yuzaki 1 1 Department of Physiology, School of Medicine, Keio University, Japan; 2 Molecular Neurophysiology, Neuroscience Research Institute, AIST, Japan Cbln1 is a newly identified antegrade transneuronal modulator. It is released from cerebellar granule cells and regulates synaptic integrity at parallel fiber-Purkinje cell synapses in the cerebellum. Indeed, we previously reported that recombinant Cbln1 specifically bound to Purkinje cell dendrites. Although Cbln1 mRNA is also highly expressed in the entorhinal cortex, its function in the hippocampus has remained uncharacterized. As a first step to address this issue, here we performed binding assays using hippocampal slice preparations. Although Cbln1 mRNA is not expressed in the hippocampus, we found that recombinant Cbln1 bound preferentially to the dentate molecular layer and the stratum lacunosum-moleculare in the hippocampus. Thus, like Cbln1 in the cerebellum, Cbln1 may serve as a new transsynaptic modulator released from presynaptic neurons in the entorhinal cortex, bind to the specific binding sites in the postsynaptic neurons in the hippocampus, and possibly regulates synapse formation and synaptic plasticity.
S129
P1-k26 Pre-surgical mapping of the brain with brain tumor
P1-k29 The application of pharmacological MRI in manganese
Takashi Nihashi 1 , Shigenori Takebayashi 2,3 , Masahiko Bundo 2 , Masazumi Fujii 3 , Toshihiko Wakabayashi 3 , Jun Yoshida 3 , Hiroyuki Fujisawa 1 , Hitomi Shimizu 1 , Kazumasa Hayasaka 1 , Shinji Naganawa 4 1 Department of Radiology, National Hospital for Geriatric Medicine, Obu, Japan; 2 Department of Neurosurgery, National Hospital for Geriatric Medicine, Japan; 3 Department of Neurosurgery, Nagoya University Graduate School of Medicine, Japan; 4 Department of Radiology, Nagoya University Graduate School of Medicine, Japan
enhancement of brain
To determine the location of central sulcus (CS) and dominant hemisphere of the language is important for presurgical mapping. We use fMRI for the patient who needs a surgery. We considered the efficacy of fMRI in our institute, retrospectively. Fifty-five patients were examined. We use five tasks, that is, tactile stimulation to bilateral palm, finger tapping, verb generation, news listening, picture naming and select suitable tasks with the clinical condition and the location with brain tumor. CS could be identified 96 and 85%, representatively by tactile stimulation and finger tapping in the affected hemisphere. The laterality of dominant hemisphere of language could be identified 78, 59, 58% by verb generation, news listening, picture naming, representatively.
P1-k27 Nonlinear local neurovascular coupling in the cerebral cortex
Jorge J. Riera 1 , Juan C. Jimenez 2 , Tohru Ozaki 3 , Ryuta Kawashima 1 , Xiaohong Wan 4 1 IDAC, Tohoku University, Sendai, Japan; 2 Institute of Cyber, Math and Physics, Havana, Cuba; 3 The Institute of Stat Math, Tokyo, Japan; 4 RIKEN Brain Science Institute, Wako, Japan We will present a biophysical model of how electrical and hemodynamic brain signals could be generated within a cortical microcolumn. The model has three components. The first is the neural mass model of three neuronal populations that responds to incoming excitatory inputs. The second and third components model the generation of measured electrical and hemodynamic meso-states, respectively. We reformulate the model in the context of the continuous-discrete state space theory in order to make inferences about the unknown parameters and the unobservable states (i.e. membrane potentials, ionic currents, NO, flow-inducing signal, CBF, CBV, dHb) from the local linearization filter and the innovation approach. Inference on this model is performed from concurrent EEG/fMRI signals obtained during a visual experiment in which a subject observes a radial checkerboard with pattern reversal at 4 Hz. JST/RISTEX; R&D promotion scheme (TAO); 21st Century Center of Excellence (COE) Program; Management Expenses Grants of Tohoku University.
P1-k28
Suppression of neural activity and hemodynamic responses during hypercapnic challenges in rats
Masahito Nemoto, Yoko Hoshi, Chie Sato Tokyo Institute of Psychiatry, Tokyo, Japan To investigate the effect of hypercapnia on the neural and hemodynamic responses, we measured electrophysiological signals (local field potentials, LFP < 100 Hz; multiunit activity, MUA > 300 Hz), optical intrinsic signals (586 and 605 nm, indicators of CBV and oxygenation) and spectral changes in reflected light. Rats were anesthetized with ␣-chloralose and artificially ventilated with muscle relaxants. Hypercapnic challenge was performed by 10% CO2 inhalation. We recorded these signals while delivering 2 s electrical pulses to the hindpaw. We observed that hemodynamic responses (CBF, CBV) were suppressed more strongly than neural responses (LFP, MUA), and prolonged deoxyhemoglobin increases in the early phase with attenuation of deoxyhemoglobin decreases in the late phase (i.e., disruption of hyperoxygenation responses). These results suggested that transfer functions from neural to hemodynamic responses may be different between normo- and hypercapnia, and imaging of early dip optical signals and positive BOLD fMRI signals may not accurately reflect neural responses during respiratory depression.
Kouichi Itoh 1 , Hirotada Fujii 2 Laboratory of Molecular Pharmacology, Tokushima Bunri University, Sanuki, Kagawa, Japan; 2 School of Health Science, Sapporo Medical University, Sapporo, Hokkaido, Japan
1
Manganese (Mn)-enhanced MRI (MEMRI) studies have been carried out extensively to visualize brain in vivo. In this paper, we observed much lower contrast enhancement in MEMRI in rats anesthetized with ketamine, compared with other anesthetics (urethane, pentobarbital, isoflurane). Ketamine is well known to be the noncompetitive antagonist for the NMDA receptors (NMDAR). Therefore, the contrast enhancement in MEMRI might be activity-dependently controlled by the NMDAR. To confirm these effects, the effects of both NMDAR and AMPAR antagonists, MK-801, and NBQX, respectively, on MEMRI were examined. When rats were treated with MK-801 remarkably inhibited the signal enhancement by Mn2+ as well as ketamine. In contrast, treatment of rats with NBQX failed to inhibit the enhancement of the signal intensity in MEMRI. These MEMRI results suggest that the signal enhancement in MEMRI in rat brains is affected by NMDAR, but not AMPAR. Research funds: a Grant-in-aid for KAKEN (15390363) and Edu and Collabo Res of Tokushima Bunri University
1 Actin-dependent regulation of Shank1 dynamics in P2-a0 Purkinje cell dendrites Toshimitsu Fuse, Haruhiko Bito Department of Biochemistry and 21st Century COE Program, University of Tokyo, Tokyo, Japan Purkinje cell dendrites possess the highest number of spines among CNS neurons. Though critical in cerebellar circuit formation, the molecular mechanisms underlying the formation and functional maturation of Purkinje cell spines are yet poorly understood. Ongoing studies suggest the existence of a tight control mechanism by which actin can efficiently accumulate in Purkinje cell spines. To gain further insights on the role of actin cytoskeleton in the organization of protein assembly at the postsynaptic density (PSD) of Purkinje cells, we studied the distribution and the redistribution of several PSD molecules present in the Purkinje cell spines upon treatment with various actin cytoskeleton-modifying reagents. Interestingly, coincidence of actin depolymerization with a prolonged 55 mM KCl depolarizing stimulation caused a robust mobilization of a key PSD scaffold molecule, Shank1, from the synapses to the dendritic shaft. Thus, neuronal activity and actin cytoskeletal reorganization may critically regulate Purkinje cell PSD assembly via control of Shank dynamics. Research fund: KAKENHI 17023010
2 Existence of specific binding sites for Cbln1 in the hipP2-a0 pocampus Tetsuro Kondo 1,2 , Takatoshi Iijima 1 , Yuichi Kamekawa 1 , Keiko Matsuda 1 , Aya Ishida 1 , Michisuke Yuzaki 1 1 Department of Physiology, School of Medicine, Keio University, Japan; 2 Molecular Neurophysiology, Neuroscience Research Institute, AIST, Japan Cbln1 is a newly identified antegrade transneuronal modulator. It is released from cerebellar granule cells and regulates synaptic integrity at parallel fiber-Purkinje cell synapses in the cerebellum. Indeed, we previously reported that recombinant Cbln1 specifically bound to Purkinje cell dendrites. Although Cbln1 mRNA is also highly expressed in the entorhinal cortex, its function in the hippocampus has remained uncharacterized. As a first step to address this issue, here we performed binding assays using hippocampal slice preparations. Although Cbln1 mRNA is not expressed in the hippocampus, we found that recombinant Cbln1 bound preferentially to the dentate molecular layer and the stratum lacunosum-moleculare in the hippocampus. Thus, like Cbln1 in the cerebellum, Cbln1 may serve as a new transsynaptic modulator released from presynaptic neurons in the entorhinal cortex, bind to the specific binding sites in the postsynaptic neurons in the hippocampus, and possibly regulates synapse formation and synaptic plasticity.