- Email: [email protected]
Properties and function of spinal interneurons in motor circuits of zebrafish
e262
Abstracts / Neuroscience Research 68S (2010) e223–e334
poor-immunoreactive compartment. These results suggest that the projection of STN neurons is not homogeneous. doi:10.1016/j.neures.2010.07.1160
P2-g02 Single-neuron tracing study of thalamocortical projections arising from the rat ventral medial nucleus by using viral vectors Eriko Kuramoto 1 , Fumino Fujiyama 1,2 , Takahiro Furuta 1 , Tomo Unzai 1 , Hiroyuki Hioki 1 , Yasuhiro Tanaka 1 , Takeshi Kaneko 1 1
Dept Morphol Brain Sci, Kyoto Univ, Kyoto 2 JST, CREST
The rat motor thalamic nuclei are composed of ventral medial (VM), ventral anterior (VA) and ventral lateral nuclei (VL). The caudodorsal portion of the VA–VL receives glutamatergic afferents from the cerebellum, whereas the VM and rostroventral portion of the VA–VL receive GABAergic afferrents from the basal ganglia. Previously we reported that axonal arborization was different between the rostroventral and caudodorsal VA–VL neurons by using single neuron-tracing method with Sindbis viral vector expressing membrane-targeted GFP. In the present study, the axonal arborization of single VM neurons was examined by the same method, and compared with the previous results of VA–VL neurons. When the axons exited from the thalamus, the reconstructed VM neurons always emitted axon collaterals to the thalamic reticular nucleus as VA–VL neurons. The VM neurons formed less axonal arborization in the striatum than rostrovental VA–VL neurons. In the cerebral cortex, the VM neurons sent axon fibers to more widespread cortical areas than VA–VL neurons, projecing to the primary motor, secondary motor, primary somatosensory, orbital, cingulate and insular areas. Of cortical layers, the axon fibers of VM neurons were most abundantly distributed in layer 1 (78.1 ± 5.6%), especially in the superficial part of layer 1. In comparison with the previously reported data of rostroventral (54%) and cuadodorsal VA–VL neurons (5.6%), VM neurons highly preferred layer 1 to other cortical layers. Although both the VM and rostroventral VA–VL have been reported to receive massive afferents mainly from the basal ganglia, the present results indicate that VM neurons more intensely innervate apical dendrites of pyramidal neurons in more widespread frontal/limbic areas than rostroventral VA–VL neurons. This suggests that, of motor thalamic neurons, VM neurons are most specialized to conrol the gain of widespread pyramidal neurons simultaneously. doi:10.1016/j.neures.2010.07.1161
P2-g03 Properties and function of spinal interneurons in motor circuits of zebrafish Yukiko Kimura 1 , Chie Satou 1 , Shin-ichi Higashijima 1,2 1
Okazaki Institute for Integrative Bioscience, NINS, Okazaki 2 National Institute for Physiological Sciences, NINS, Okazaki The simple motor behaviors that underlie locomotion relies on motor circuits that are embedded in the spinal cord. What types of interneurons make up the circuits and how each type of neurons participates in the generation of locomotion are fundamental questions to understand the mechanism of locomotion. Recent molecular genetic studies have suggested four cardinal classes of interneurons (V0, V1, V2, and V3) can be distinguished on the basis of their developmental origin and combinatorial transcription factor expression in the ventral spinal cord of vertebrates. Thus, we have been generating several transgenic zebrafish lines that express GFP under the control of promoter/enhancer of the particular transcription factors, in the hope that generation of such lines would facilitate the characterization of particular interneurons. We have made transgenic fish with the following genes: chx10 (a marker for V2a neurons), gata3 (V2b neurons), and nkx2.2 (V3 neurons). Anatomical and physiological analyses of GFP neurons in these transgenic fish will be presented. In addition, we will present optogenetic analysis of these classes of spinal interneurons. doi:10.1016/j.neures.2010.07.1162
P2-g04 Effect of bilateral lesion of superior colliculus on spontaneous movement in rats Yasutaka Noda , Yukako Hasegawa, Ryouhei Hasegawa Human Tech. Res. Inst., AIST We examined the function of the rat superior colliculus (SC) in spontaneous movements. The SC is thought to play an important role in visually orienting behaviors in many species. To examine the function of the SC in behaving rats, we tested if bilateral lesions of the anterior SC would affect execution
and/or inhibition of spontaneous movements. We used running wheels to measure the level of spontaneous movements. The activity level after the lesion was significantly increased in 3 of 8 rats from that before the lesion (4 were unchanged and 1 was decreased). These results suggest that the anterior SC may be related to inhibit movements while the posterior SC is important to execute them. doi:10.1016/j.neures.2010.07.1163
P2-g05 Characterization of DRG neuron subpopulations selectively expressing ChR2 in Thy-1.2 transgenic rat Zhigang Ji 1,3 , Toru Ishizuka 1,4 , Yugo Fukazawa 2,4 , Ryuichi Shigemoto 2 , Hiromu Yawo 1,3,4 1
Tohoku University Graduate School of Life Sciences 2 National Institute for Physiological Sciences, Okazaki, Japan 3 Tohoku University Basic and Translational Research Center for Global Brain Science, Sendai, Japan 4 Japan Science and Technology Agency, CREST, Tokyo, Japan ChR2 (channelrhodopsin-2) is a light activated nonselective cation channel isolated from one of green alga chlamydomonas reinhardtii. Once expressed in neurons, it can transmit light energy into neural activity. We generated a transgenic rat model that expresses ChR2-Venus broadly throughout the nervous system under control of the Thy-1.2 promoter. The region and cell type expressing ChR2 in spinal cord and dorsal root ganglion (DRG) were investigated using immunohistochemistry. In spinal cord, ChR2 was expressed any lamina of gray matter except for lamina I and outer part of lamina II. In DRG, ChR2 was expressed in large-diameter neurons which are reactive to anti-NF200 whereas not in small-diameter neurons. It is suggested that the DRG neurons expressing ChR2 are involved in fast-conducting pain sensation or proprioception which get information from muscle spindle, Golgi tendon organs, and joint receptors. doi:10.1016/j.neures.2010.07.1164
P2-g06 Influence of object size on corticospinal excitability during motor imagery with passively holding the object Nobuaki Mizuguchi 1,2 , Masanori Sakamoto 3 , Tetsuro Muraoka 4 , Kento Nakagawa 1 , Shoichi Kanazawa 1 , Hiroki Nakata 3 , Kazuyuki Kanosue 3 1 4
Grad Sch of Sport Sci, Waseda Univ College of Economics, Nihon Univ
2
JPSP
3
Fac Sport Sci, Waseda Univ
Motor imagery is defined as the mental execution of movement without any overt movement or without any muscle activation. Motor imagery appears to improve motor performances during skill acquisition in sports or in the recovery of motor function following a stroke. Recently, we used transcranial magnetic stimulation (TMS), and demonstrated that corticospinal excitability during imagery of actions with an external object would be influenced by actually touching the object (Mizuguchi et al., 2009). In the present study, we investigated whether corticospinal excitability during motor imagery involving an external object was influenced by object size. Twelve healthy male volunteers participated in the experiment. Subjects were asked to imagine squeezing a palm-size ball (4 cm diameter) with the right hand at one’s full strength from a first person perspective. The recordings during the imagery were conducted in four conditions (1) grabbing posture with holding nothing, (2) grabbing posture with holding the palm-size ball passively, (3) pinching posture with holding nothing, and (4) pinching posture with holding a smallsize ball (2 cm diameter) passively. Corticospinal excitability was assessed on the basis of the amplitudes of motor evoked potentials (MEPs) in the first dorsal interosseous muscle following TMS over the motor cortex during the imagery. The intensity of TMS was set at 120% of the resting motor threshold. The MEPs amplitude during the imagery was larger when a ball was held than that when the ball was not held. The enhancement of MEPs was larger when palm-size ball (compatible) was held than that when the small-size ball (incompatible) was held. These results suggested that the compatible afferent input with motor imagery enhanced corticospinal excitability during motor imagery. doi:10.1016/j.neures.2010.07.1165
Abstracts / Neuroscience Research 68S (2010) e223–e334
poor-immunoreactive compartment. These results suggest that the projection of STN neurons is not homogeneous. doi:10.1016/j.neures.2010.07.1160
P2-g02 Single-neuron tracing study of thalamocortical projections arising from the rat ventral medial nucleus by using viral vectors Eriko Kuramoto 1 , Fumino Fujiyama 1,2 , Takahiro Furuta 1 , Tomo Unzai 1 , Hiroyuki Hioki 1 , Yasuhiro Tanaka 1 , Takeshi Kaneko 1 1
Dept Morphol Brain Sci, Kyoto Univ, Kyoto 2 JST, CREST
The rat motor thalamic nuclei are composed of ventral medial (VM), ventral anterior (VA) and ventral lateral nuclei (VL). The caudodorsal portion of the VA–VL receives glutamatergic afferents from the cerebellum, whereas the VM and rostroventral portion of the VA–VL receive GABAergic afferrents from the basal ganglia. Previously we reported that axonal arborization was different between the rostroventral and caudodorsal VA–VL neurons by using single neuron-tracing method with Sindbis viral vector expressing membrane-targeted GFP. In the present study, the axonal arborization of single VM neurons was examined by the same method, and compared with the previous results of VA–VL neurons. When the axons exited from the thalamus, the reconstructed VM neurons always emitted axon collaterals to the thalamic reticular nucleus as VA–VL neurons. The VM neurons formed less axonal arborization in the striatum than rostrovental VA–VL neurons. In the cerebral cortex, the VM neurons sent axon fibers to more widespread cortical areas than VA–VL neurons, projecing to the primary motor, secondary motor, primary somatosensory, orbital, cingulate and insular areas. Of cortical layers, the axon fibers of VM neurons were most abundantly distributed in layer 1 (78.1 ± 5.6%), especially in the superficial part of layer 1. In comparison with the previously reported data of rostroventral (54%) and cuadodorsal VA–VL neurons (5.6%), VM neurons highly preferred layer 1 to other cortical layers. Although both the VM and rostroventral VA–VL have been reported to receive massive afferents mainly from the basal ganglia, the present results indicate that VM neurons more intensely innervate apical dendrites of pyramidal neurons in more widespread frontal/limbic areas than rostroventral VA–VL neurons. This suggests that, of motor thalamic neurons, VM neurons are most specialized to conrol the gain of widespread pyramidal neurons simultaneously. doi:10.1016/j.neures.2010.07.1161
P2-g03 Properties and function of spinal interneurons in motor circuits of zebrafish Yukiko Kimura 1 , Chie Satou 1 , Shin-ichi Higashijima 1,2 1
Okazaki Institute for Integrative Bioscience, NINS, Okazaki 2 National Institute for Physiological Sciences, NINS, Okazaki The simple motor behaviors that underlie locomotion relies on motor circuits that are embedded in the spinal cord. What types of interneurons make up the circuits and how each type of neurons participates in the generation of locomotion are fundamental questions to understand the mechanism of locomotion. Recent molecular genetic studies have suggested four cardinal classes of interneurons (V0, V1, V2, and V3) can be distinguished on the basis of their developmental origin and combinatorial transcription factor expression in the ventral spinal cord of vertebrates. Thus, we have been generating several transgenic zebrafish lines that express GFP under the control of promoter/enhancer of the particular transcription factors, in the hope that generation of such lines would facilitate the characterization of particular interneurons. We have made transgenic fish with the following genes: chx10 (a marker for V2a neurons), gata3 (V2b neurons), and nkx2.2 (V3 neurons). Anatomical and physiological analyses of GFP neurons in these transgenic fish will be presented. In addition, we will present optogenetic analysis of these classes of spinal interneurons. doi:10.1016/j.neures.2010.07.1162
P2-g04 Effect of bilateral lesion of superior colliculus on spontaneous movement in rats Yasutaka Noda , Yukako Hasegawa, Ryouhei Hasegawa Human Tech. Res. Inst., AIST We examined the function of the rat superior colliculus (SC) in spontaneous movements. The SC is thought to play an important role in visually orienting behaviors in many species. To examine the function of the SC in behaving rats, we tested if bilateral lesions of the anterior SC would affect execution
and/or inhibition of spontaneous movements. We used running wheels to measure the level of spontaneous movements. The activity level after the lesion was significantly increased in 3 of 8 rats from that before the lesion (4 were unchanged and 1 was decreased). These results suggest that the anterior SC may be related to inhibit movements while the posterior SC is important to execute them. doi:10.1016/j.neures.2010.07.1163
P2-g05 Characterization of DRG neuron subpopulations selectively expressing ChR2 in Thy-1.2 transgenic rat Zhigang Ji 1,3 , Toru Ishizuka 1,4 , Yugo Fukazawa 2,4 , Ryuichi Shigemoto 2 , Hiromu Yawo 1,3,4 1
Tohoku University Graduate School of Life Sciences 2 National Institute for Physiological Sciences, Okazaki, Japan 3 Tohoku University Basic and Translational Research Center for Global Brain Science, Sendai, Japan 4 Japan Science and Technology Agency, CREST, Tokyo, Japan ChR2 (channelrhodopsin-2) is a light activated nonselective cation channel isolated from one of green alga chlamydomonas reinhardtii. Once expressed in neurons, it can transmit light energy into neural activity. We generated a transgenic rat model that expresses ChR2-Venus broadly throughout the nervous system under control of the Thy-1.2 promoter. The region and cell type expressing ChR2 in spinal cord and dorsal root ganglion (DRG) were investigated using immunohistochemistry. In spinal cord, ChR2 was expressed any lamina of gray matter except for lamina I and outer part of lamina II. In DRG, ChR2 was expressed in large-diameter neurons which are reactive to anti-NF200 whereas not in small-diameter neurons. It is suggested that the DRG neurons expressing ChR2 are involved in fast-conducting pain sensation or proprioception which get information from muscle spindle, Golgi tendon organs, and joint receptors. doi:10.1016/j.neures.2010.07.1164
P2-g06 Influence of object size on corticospinal excitability during motor imagery with passively holding the object Nobuaki Mizuguchi 1,2 , Masanori Sakamoto 3 , Tetsuro Muraoka 4 , Kento Nakagawa 1 , Shoichi Kanazawa 1 , Hiroki Nakata 3 , Kazuyuki Kanosue 3 1 4
Grad Sch of Sport Sci, Waseda Univ College of Economics, Nihon Univ
2
JPSP
3
Fac Sport Sci, Waseda Univ
Motor imagery is defined as the mental execution of movement without any overt movement or without any muscle activation. Motor imagery appears to improve motor performances during skill acquisition in sports or in the recovery of motor function following a stroke. Recently, we used transcranial magnetic stimulation (TMS), and demonstrated that corticospinal excitability during imagery of actions with an external object would be influenced by actually touching the object (Mizuguchi et al., 2009). In the present study, we investigated whether corticospinal excitability during motor imagery involving an external object was influenced by object size. Twelve healthy male volunteers participated in the experiment. Subjects were asked to imagine squeezing a palm-size ball (4 cm diameter) with the right hand at one’s full strength from a first person perspective. The recordings during the imagery were conducted in four conditions (1) grabbing posture with holding nothing, (2) grabbing posture with holding the palm-size ball passively, (3) pinching posture with holding nothing, and (4) pinching posture with holding a smallsize ball (2 cm diameter) passively. Corticospinal excitability was assessed on the basis of the amplitudes of motor evoked potentials (MEPs) in the first dorsal interosseous muscle following TMS over the motor cortex during the imagery. The intensity of TMS was set at 120% of the resting motor threshold. The MEPs amplitude during the imagery was larger when a ball was held than that when the ball was not held. The enhancement of MEPs was larger when palm-size ball (compatible) was held than that when the small-size ball (incompatible) was held. These results suggested that the compatible afferent input with motor imagery enhanced corticospinal excitability during motor imagery. doi:10.1016/j.neures.2010.07.1165