- Email: [email protected]
Single-neuron tracing study of the external segment of the globus pallidus in rat with a Sindbis viral vector
e104
Abstracts / Neuroscience Research 68S (2010) e55–e108
and other: mirror neurons fire regardless of the agent of action. Here we report that the medial frontal cortex has a clearly distinct neural code for self and other actions in addition to a mirror-like property. We trained pairs of monkeys on a task that required them to monitor each other?s action for optimal behavioral planning. We recorded and analyzed neuronal activity in the medial frontal cortex, including the pre-supplementary motor area (preSMA) and the anterior cingulate cortex (ACC), which has been suggested to participate in social cognition. We found a population of neurons that discharged selectively for the action of one?s own (self type) and another population for the action of one?s partner (partner type). Yet other neurons fired nonselectively with respect to the agent of action (dual type). The pre-SMA and its rostrally adjoining region contained significantly larger proportion of partner-type neurons than did the ACC. Such agent-related activity was not accounted for by a difference in gaze direction or by an idiosyncratic pattern of muscular activation. We further found a significant paucity of the partner type and dual type in a monkey exhibiting difficulty in exclusively monitoring the action of other. These findings suggest that the medial frontal cortex participates in differentiating the agent of action and in monitoring the behavior of others.
co-administration of the 5-HT1A agonist 8-OH-DPAT, which acts on autoreceptors and inhibits 5-HT neural activity. In vivo microdialysis showed that GABAB activation in the DRN increased extracellular 5-HT level in the medial prefrontal cortex. This may be due to an indirect action via presynaptic GABAB receptors. The presynaptic GABAB receptors suppress Ca2+ channel activity and inhibit neurotransmission, and the co-administration of N-type Ca2+ channel blocker facilitated the effect of baclofen. These findings suggest that the indirect disinhibition of 5-HT neuron activity by presynaptic GABAB receptors on non-5-HT neurons in the DRN is one of the neurobiological mechanisms of escalated aggression. doi:10.1016/j.neures.2010.07.223
O2-9-4-1 Rhythmic firing of pedunculopontine tegmental nucleus neurons in behaving monkeys Ken-ichi Okada 1 , Yasushi Kobayashi 1,2 1
Graduate school of frontier biosciences, Osaka University, Toyonaka Computational Neuroscience Laboratories, ATR, Kyoto, 3 PRESTO, Japan Science and Technology Agency, Saitama
2
doi:10.1016/j.neures.2010.07.221
O2-9-3-3 Imprinting induces predisposed preference to biological motion in newly-hatched domestic chicks Toshiya Matsushima 1 , Momoko Miura 1 , Lucia Regolin 2 , Giorgio Vallortigara 3 1
Dept Biol Sci, Fac Sci, Hokkaido Univ, Sapporo 2 University of Padova, Padova, Italy 3 University of Trento, Revoreto, Italy
If appropriately arranged, a motion picture composed of a set of moving points of light creates a vivid perception of living organism engaged in coordinated activity such as walking, a phenomena known as Johansson’s biological motion (BM). Despite intensive studies in human subjects, the perception of BM has been examined in relatively few species of animals such as pigeons, monkeys and chimpanzees. Recently, it was shown that newlyhatched domestic chicks reveal predisposition to a BM stimulus mimicking a walking hen (WH) over a motion picture of a rigidly rotating hen (RH) (Vallortigara et al. 2005). On the other hand, bioluminescent signal of c-fos gene expression in IMM region proved to be significantly correlated with the behavioral score of imprinting (Yamaguchi et al. 2010). To localize the brain regions involved in the BM perception, we imprinted chicks by a variety of BM and non-BM stimuli. When imprinted to WH (a BM stimulus), the trained chicks showed a clear preference to WH over RH in binary choices. However, WH preference was induced even in chicks imprinted by RH. Furthermore, a variety of non-BM motion pictures (pendulum and random motion) were similarly effective in inducing the BM preference particularly in males. These chicks preferred a walking hen (WH) also in binary choice between a WH and a WC (BM motion mimicking a walking cat), suggesting that the chicks may discriminate predators by BM. Chicks trained by a stationary picture of light points showed a negligible preference to WH as in naïve control chicks. Early non-specific visual experiences may have enhanced an innately predisposed preference to BM. doi:10.1016/j.neures.2010.07.222
O2-9-3-4 GABAB receptor modulation of serotonin neurons in the dorsal raphe nucleus escalates aggression in mice
Aki Takahashi 1,2 , Akiko Shimamoto 2 , Christopher O. Boyson 2 , Tsuyoshi Koide 1 , Joseph F. DeBold 2 , Klaus A. Miczek 2 1 Mouse Genomics Resource Laboratory, National Institute of Genetics (NIG), Mishima 2 Dept Psychology, Tufts University, Boston U.S.A
The serotonin (5-HT) system in the brain has been studied more than any other neurotransmitter for its role in the neurobiological basis of aggression. However, which mechanisms modulate the 5-HT system to promote escalated aggression is not clear. We here explore the role of GABAergic modulation in the raphe nuclei, from where most 5-HT in the forebrain originates, on escalated aggression in male mice. Pharmacological activation of GABAB, but not GABAA, receptors in the dorsal raphe nucleus (DRN) escalated aggressive behaviors. In contrast, GABA agonists did not escalate aggressive behaviors after microinjection into the median raphe nucleus (MRN). The aggression-heightening effect of the GABAB agonist baclofen depended on the activation of 5-HT neurons in the DRN because it was blocked by
The pedunculopontine tegmental nucleus (PPTN) has ascending and descending connections with numerous brain regions and consists of cholinergic and non-cholinergic (GABAergic, glutamatergic) neurons. Projections to the entire thalamus and reciprocal connections with the basal ganglia nuclei suggest a possible role for the PPTN in the control of various rhythmic behaviors including locomotion and wake/sleep control. Previous studies demonstrated that PPTN neurons showed a rhythmic firing with locomotion and sleep in cats. However, the firing properties of PPTN neurons in behaving monkeys still remains unclear. We recorded the activity of PPTN neurons in monkeys during visually guided saccade tasks, and analyzed their regularity of firing during different task periods. Autocorrelation, Fourier analysis and coefficient of variation (CV) of inter-spike intervals were used to quantify the tendency of firing regularity. On average, PPTN neurons increased discharge rate and showed low CV during the task execution period compared with the inter-trial interval period, although individual neurons exhibited a variety of temporal response profiles. A group of PPTN neurons exhibited a clear periodicity of firing and half of them showed a low-frequency oscillation (∼10 Hz). Some of these neurons showed a transient pause in activity during saccade execution, and rhythmic firing aroused again that were phase-locked to the saccade end. Another group of neurons fired randomly and exhibited a burst of spikes. The rest of the neurons did not show any periodicity of firing but fired regularly; most of them had a CV of < 1 (the CV of a Poisson process). To explore the factors affecting firing regularity for each neuron, the CV was examined as a function of firing rate and task period. For half of the neurons, the relationship between CV and firing rate depended on the task period. Thus, behavioral context dependent factors might contribute to discharge variability of PPTN neurons. doi:10.1016/j.neures.2010.07.224
O2-9-4-2 Single-neuron tracing study of the external segment of the globus pallidus in rat with a Sindbis viral vector Fumino Fujiyama 1,2 Takeshi Kaneko 1 1
, Takashi
Nakano 1 , Takahiro
Furuta 1 ,
Dept Morphol Brain Sci, Gard Med Sch, Kyoto Univ, Kyoto 2 JST, CREST, Japan
The external segment of the globus pallidus (GPe) is known as a relay nucleus in the indirect pathway of the basal ganglia. In this scheme, the GPe is thought to receive the information from the striatum by the striatopallidal neurons (striatal indirect pathway neurons) and send it to the basal ganglia output nuclei, which are the internal segment of the globus pallidus (GPi) and the pars reticulata of the substantia nigra (SNr), through a relay in the subthalamic nucleus (STN). On the other hand, the striatonigral neurons (striatal direct pathway neurons) are thought to aim directly basal ganglia output nuclei (GPi/SNr). However, we recently reported that the striatal direct pathway neurons also gave collaterals in GPe, although the targeted regions in GPe were different from the ones terminated by the striatal indirect pathway neurons. Our next question is whether the single GPe neurons located in the region targeted by striatal direct pathway neurons project to the structures as a relay nucleus of the indirect pathways; STN and GPi/SNr. To reveal it, the single GPe neurons in rat were labeled by recombinant Sindbis virus that is designed to express membrane-targeted green fluorescent protein. In the present study, we show the axonal reconstruction of the single GPe neurons entirely and discuss the possibility that the GPe is
Abstracts / Neuroscience Research 68S (2010) e55–e108
e105
separated functionally to be involved in the different pathways of the basal ganglia.
reciprocally inhibited by the lateral SC representing downward saccades in the opposite SC and vice versa.
doi:10.1016/j.neures.2010.07.225
doi:10.1016/j.neures.2010.07.227
O2-9-4-3 Intermittent visual feedback can boost visuomotor learning in rhythmic movements
O2-10-1-1 Neural network model of C. elegans
Ikegami 1,2,3
Tsuyoshi Nozaki 1,3 1
, Masaya
Hirashima 1 ,
Rieko
Osu 2,3 ,
2
Daichi 3
The Univ of Tokyo Computational Neuroscience Laboratories, ATR NICT
Our previous study (Ikegami et al., J Neurosci., 2010) has reported that the performance of motor adaptation to a visuomotor rotation deteriorated for rhythmic movement as compared to that for discrete movement. This result may imply that the two types of movements differently utilize visual error information to update the states of motor learning processes. To investigate how the visual error modifies the subsequent rhythmic movements by a system identification technique, we had 8 participants perform rhythmic out-and-back reaching movements (the duration of one cycle, ∼ 400 ms) in the presence of visuomotor rotations whose magnitude varied randomly from cycle to cycle. The identified model revealed that the motor learning processes used the error information of up to 5 cycles in the past. Furthermore, it successfully reproduced the learning curve with higher plateau and slower time constant obtained in our previous study applying a constant 30◦ counterclockwise (CCW) rotation. Thus, making reference to the errors in a number of previous cycles may contaminate the learning processes of rhythmic movements. If it is true, then providing visual feedback intermittently can enhance the performance of the motor learning, especially when it is provided once every 5 cycles. To test this possibility, 43 participants were asked to adapt to 30◦ CCW rotation in one of the following 4 conditions: the visual feedback of the hand position was provided for all cycles (CON condition (n = 15)) and for only once every 2, 3, or 5 cycles (INT2 (n = 8), INT3 (n = 5), and INT5 (n = 15) conditions, respectively). The motor learning performance was not different from that in CON condition in INT2 and INT3 conditions, but significantly enhanced in INT5 condition, suggesting that visual error information provided within 2 s (i.e., 5 cycles x 400 ms) after a cycle would have harmful effects on the correction of the motor command in the subsequent cycles. doi:10.1016/j.neures.2010.07.226
O2-9-4-4 Topographic organization of commissural connections between the two superior colliculi and their functional roles for generating horizontal and vertical Saccades Mayu Takahashi , Yuriko Sugiuchi, Yoshikazu Shinoda Department of Systems Neurophysiology, Tokyo Medical and Dental University, Tokyo The pathway that interconnects the two superior colliculi (SCs) is considered to be important for visual-orienting behavior. Our electrophysiological study indicated that medial tectoreticular neurons (TRNs) in the rostral SC received strong commissural excitation from the medial part of the opposite rostral SC, whereas lateral TRNs received strong excitation from its lateral part, and medial and lateral TRNs received strong inhibition from the lateral and medial part of the opposite rostral SC, respectively. To provide morphological evidence for these electrophysiological findings, we examined tectal distribution of commissural excitatory and inhibitory neurons in the cat SC by injecting tracers into various parts of the SC, and the Forel’s field H (FFH). Double-labelling with GABA and gold particle-conjugated WGA -HRP (GP) was used to identify commissural neurons as GABAergic. Caudal SC injection labeled small-sized GABA-positive neurons (<200 m2 ) only in the opposite rostral SC, whereas rostral SC injection labeled medium-sized GABA-negative (200–700 m2 ) and small-sized commissural neurons in the opposite rostral SC. Lateral SC injection labeled small GABAergic neurons in the medial part of the opposite SC and non-GABAergic medium-sized neurons in its lateral part, whereas medial SC injection labeled small GABAergic neurons in the lateral part of the opposite SC and non-GABAergic medium-sized neurons in its medial part. Many of these medium-sized commissural neurons were TRNs projecting to the ipsilateral FFH with commissural collaterals to the opposite SC. These results provided morphological evidence to support that mirrorsymmetric excitation between medial - medial and lateral - lateral parts of the SCs plays an important role in conjugate upward and downward vertical saccades, respectively, and the medial SC representing upward saccades is
Ryuzo Shingai 1 , Hisanori Takahashi 1 , Yuishi Iwasaki 2 , Tokumitsu Wakabayashi 1 , Tarou Ogurusu 1 1
Dept of Applied Chemistry and Bioengineering, Iwate University 2 Faculty of Engineering, Ibaraki University, Hitachi, Japan To estimate functions of the nervous system of C. elegans in behavioral states, we constructed a neural network model that regulates chemotaxis and thermotaxis behaviors. Synaptic excitatory/inhibitory properties were assigned to be consistent to those predicted in published articles, and the excitatory/inhibitory properties of other synapses were assigned such that when thermal/chemical stimuli are given to sensory neurons, the interneurons which determine forward/backward movement show proper potential changes. Several interneurons and motor neurons in the obtained network showed specific patterns of excitatory or inhibitory responses to stimuli which were given simultaneously to different sensory neurons. We will also discuss the response of the circuit when noisy stimulus is input to the sensory neuron. doi:10.1016/j.neures.2010.07.228
O2-10-1-2 Multi-physical full-scale simulation for neuronal morphogenesis Seigo Nonaka , Naoki Honda, Shin Ishii Graduate School of Informatics, Kyoto University During embryonic development, cells differentiate to various types with specific morphologies which correspond to cellular functions. For examples, motile cells have structures of lamellipodia and filopodia and neurons are prominently polarized with axon and dendrites.The cellular morphogenesis is a complicated phenomenon, during which a cell receives extracellular signals and processes those through intracellular signal transduction, which controls the cell shape by regulating the reorganization of cytoskeleton such as actin filaments (F-actin) and microtubules. Although microscopic properties of cytoskeleton such as (de-)polymerization, capping and branching have been identified, filament-based understanding for macroscopic morphogenesis remains largely unclear.To fill in this hierarchical gap between microand macro-scopic phenomena, we constructed a multi-physical simulator for dynamics of cellular morphology, which is a system of reaction-diffusion of regulating molecules, F-actin and plasma membrane. In this simulation, the reaction-diffusion field and the membrane are discretized into multiple compartments and nodes, respectively. A F-actin is represented as a line segment and generates driving force against the membrane based on the elastic-ratchet model. Using this simulator, we demonstrated chemotactic migration.For realistic simulation, there was a problem of computational cost, because of the large number (∼108 ) of F-actin expressed inside a cell. The most expensive calculation is the collision detection between F-actin and membrane nodes. To resolve this problem, we adopted parallelization technique (in computer science) to allocate the partial simulation processes related to F-actin to multiple CPUs so that the collision detection is performed independently on each CPU. This parallelization successfully accelerated the run-speed almost linearly to the number of CPUs in some conditions. We also report some additional biological applications. doi:10.1016/j.neures.2010.07.229
O2-10-1-3 Prominent features of layer-specific in vivo activity arise from the structure of the cortical microcircuit Tobias C. Potjans 1,2 , Markus Diesmann 1,3 1
Brain and Neural Systems Team, RIKEN CSRP, Wako, Japan 2 Institute of Neurosciences and Medicine, Research Center Juelich, Germany 3 RIKEN Brain Science Institute, Wako, Japan The layer-specific structure of neuronal microcircuits has been hypothesized to play a crucial part in brain function. In the past decade, detailed connectivity maps of the local cortical network have been assembled (Binzegger et al., 2004, Thomson and Lamy, 2007) and cell-type specific recordings revealed the neuronal activity in vivo (de Kock and Sakmann, 2009; Sakata and Harris, 2009). The relationship of prominent connectivity features and the experimentally observed activity is nevertheless elusive.
Abstracts / Neuroscience Research 68S (2010) e55–e108
and other: mirror neurons fire regardless of the agent of action. Here we report that the medial frontal cortex has a clearly distinct neural code for self and other actions in addition to a mirror-like property. We trained pairs of monkeys on a task that required them to monitor each other?s action for optimal behavioral planning. We recorded and analyzed neuronal activity in the medial frontal cortex, including the pre-supplementary motor area (preSMA) and the anterior cingulate cortex (ACC), which has been suggested to participate in social cognition. We found a population of neurons that discharged selectively for the action of one?s own (self type) and another population for the action of one?s partner (partner type). Yet other neurons fired nonselectively with respect to the agent of action (dual type). The pre-SMA and its rostrally adjoining region contained significantly larger proportion of partner-type neurons than did the ACC. Such agent-related activity was not accounted for by a difference in gaze direction or by an idiosyncratic pattern of muscular activation. We further found a significant paucity of the partner type and dual type in a monkey exhibiting difficulty in exclusively monitoring the action of other. These findings suggest that the medial frontal cortex participates in differentiating the agent of action and in monitoring the behavior of others.
co-administration of the 5-HT1A agonist 8-OH-DPAT, which acts on autoreceptors and inhibits 5-HT neural activity. In vivo microdialysis showed that GABAB activation in the DRN increased extracellular 5-HT level in the medial prefrontal cortex. This may be due to an indirect action via presynaptic GABAB receptors. The presynaptic GABAB receptors suppress Ca2+ channel activity and inhibit neurotransmission, and the co-administration of N-type Ca2+ channel blocker facilitated the effect of baclofen. These findings suggest that the indirect disinhibition of 5-HT neuron activity by presynaptic GABAB receptors on non-5-HT neurons in the DRN is one of the neurobiological mechanisms of escalated aggression. doi:10.1016/j.neures.2010.07.223
O2-9-4-1 Rhythmic firing of pedunculopontine tegmental nucleus neurons in behaving monkeys Ken-ichi Okada 1 , Yasushi Kobayashi 1,2 1
Graduate school of frontier biosciences, Osaka University, Toyonaka Computational Neuroscience Laboratories, ATR, Kyoto, 3 PRESTO, Japan Science and Technology Agency, Saitama
2
doi:10.1016/j.neures.2010.07.221
O2-9-3-3 Imprinting induces predisposed preference to biological motion in newly-hatched domestic chicks Toshiya Matsushima 1 , Momoko Miura 1 , Lucia Regolin 2 , Giorgio Vallortigara 3 1
Dept Biol Sci, Fac Sci, Hokkaido Univ, Sapporo 2 University of Padova, Padova, Italy 3 University of Trento, Revoreto, Italy
If appropriately arranged, a motion picture composed of a set of moving points of light creates a vivid perception of living organism engaged in coordinated activity such as walking, a phenomena known as Johansson’s biological motion (BM). Despite intensive studies in human subjects, the perception of BM has been examined in relatively few species of animals such as pigeons, monkeys and chimpanzees. Recently, it was shown that newlyhatched domestic chicks reveal predisposition to a BM stimulus mimicking a walking hen (WH) over a motion picture of a rigidly rotating hen (RH) (Vallortigara et al. 2005). On the other hand, bioluminescent signal of c-fos gene expression in IMM region proved to be significantly correlated with the behavioral score of imprinting (Yamaguchi et al. 2010). To localize the brain regions involved in the BM perception, we imprinted chicks by a variety of BM and non-BM stimuli. When imprinted to WH (a BM stimulus), the trained chicks showed a clear preference to WH over RH in binary choices. However, WH preference was induced even in chicks imprinted by RH. Furthermore, a variety of non-BM motion pictures (pendulum and random motion) were similarly effective in inducing the BM preference particularly in males. These chicks preferred a walking hen (WH) also in binary choice between a WH and a WC (BM motion mimicking a walking cat), suggesting that the chicks may discriminate predators by BM. Chicks trained by a stationary picture of light points showed a negligible preference to WH as in naïve control chicks. Early non-specific visual experiences may have enhanced an innately predisposed preference to BM. doi:10.1016/j.neures.2010.07.222
O2-9-3-4 GABAB receptor modulation of serotonin neurons in the dorsal raphe nucleus escalates aggression in mice
Aki Takahashi 1,2 , Akiko Shimamoto 2 , Christopher O. Boyson 2 , Tsuyoshi Koide 1 , Joseph F. DeBold 2 , Klaus A. Miczek 2 1 Mouse Genomics Resource Laboratory, National Institute of Genetics (NIG), Mishima 2 Dept Psychology, Tufts University, Boston U.S.A
The serotonin (5-HT) system in the brain has been studied more than any other neurotransmitter for its role in the neurobiological basis of aggression. However, which mechanisms modulate the 5-HT system to promote escalated aggression is not clear. We here explore the role of GABAergic modulation in the raphe nuclei, from where most 5-HT in the forebrain originates, on escalated aggression in male mice. Pharmacological activation of GABAB, but not GABAA, receptors in the dorsal raphe nucleus (DRN) escalated aggressive behaviors. In contrast, GABA agonists did not escalate aggressive behaviors after microinjection into the median raphe nucleus (MRN). The aggression-heightening effect of the GABAB agonist baclofen depended on the activation of 5-HT neurons in the DRN because it was blocked by
The pedunculopontine tegmental nucleus (PPTN) has ascending and descending connections with numerous brain regions and consists of cholinergic and non-cholinergic (GABAergic, glutamatergic) neurons. Projections to the entire thalamus and reciprocal connections with the basal ganglia nuclei suggest a possible role for the PPTN in the control of various rhythmic behaviors including locomotion and wake/sleep control. Previous studies demonstrated that PPTN neurons showed a rhythmic firing with locomotion and sleep in cats. However, the firing properties of PPTN neurons in behaving monkeys still remains unclear. We recorded the activity of PPTN neurons in monkeys during visually guided saccade tasks, and analyzed their regularity of firing during different task periods. Autocorrelation, Fourier analysis and coefficient of variation (CV) of inter-spike intervals were used to quantify the tendency of firing regularity. On average, PPTN neurons increased discharge rate and showed low CV during the task execution period compared with the inter-trial interval period, although individual neurons exhibited a variety of temporal response profiles. A group of PPTN neurons exhibited a clear periodicity of firing and half of them showed a low-frequency oscillation (∼10 Hz). Some of these neurons showed a transient pause in activity during saccade execution, and rhythmic firing aroused again that were phase-locked to the saccade end. Another group of neurons fired randomly and exhibited a burst of spikes. The rest of the neurons did not show any periodicity of firing but fired regularly; most of them had a CV of < 1 (the CV of a Poisson process). To explore the factors affecting firing regularity for each neuron, the CV was examined as a function of firing rate and task period. For half of the neurons, the relationship between CV and firing rate depended on the task period. Thus, behavioral context dependent factors might contribute to discharge variability of PPTN neurons. doi:10.1016/j.neures.2010.07.224
O2-9-4-2 Single-neuron tracing study of the external segment of the globus pallidus in rat with a Sindbis viral vector Fumino Fujiyama 1,2 Takeshi Kaneko 1 1
, Takashi
Nakano 1 , Takahiro
Furuta 1 ,
Dept Morphol Brain Sci, Gard Med Sch, Kyoto Univ, Kyoto 2 JST, CREST, Japan
The external segment of the globus pallidus (GPe) is known as a relay nucleus in the indirect pathway of the basal ganglia. In this scheme, the GPe is thought to receive the information from the striatum by the striatopallidal neurons (striatal indirect pathway neurons) and send it to the basal ganglia output nuclei, which are the internal segment of the globus pallidus (GPi) and the pars reticulata of the substantia nigra (SNr), through a relay in the subthalamic nucleus (STN). On the other hand, the striatonigral neurons (striatal direct pathway neurons) are thought to aim directly basal ganglia output nuclei (GPi/SNr). However, we recently reported that the striatal direct pathway neurons also gave collaterals in GPe, although the targeted regions in GPe were different from the ones terminated by the striatal indirect pathway neurons. Our next question is whether the single GPe neurons located in the region targeted by striatal direct pathway neurons project to the structures as a relay nucleus of the indirect pathways; STN and GPi/SNr. To reveal it, the single GPe neurons in rat were labeled by recombinant Sindbis virus that is designed to express membrane-targeted green fluorescent protein. In the present study, we show the axonal reconstruction of the single GPe neurons entirely and discuss the possibility that the GPe is
Abstracts / Neuroscience Research 68S (2010) e55–e108
e105
separated functionally to be involved in the different pathways of the basal ganglia.
reciprocally inhibited by the lateral SC representing downward saccades in the opposite SC and vice versa.
doi:10.1016/j.neures.2010.07.225
doi:10.1016/j.neures.2010.07.227
O2-9-4-3 Intermittent visual feedback can boost visuomotor learning in rhythmic movements
O2-10-1-1 Neural network model of C. elegans
Ikegami 1,2,3
Tsuyoshi Nozaki 1,3 1
, Masaya
Hirashima 1 ,
Rieko
Osu 2,3 ,
2
Daichi 3
The Univ of Tokyo Computational Neuroscience Laboratories, ATR NICT
Our previous study (Ikegami et al., J Neurosci., 2010) has reported that the performance of motor adaptation to a visuomotor rotation deteriorated for rhythmic movement as compared to that for discrete movement. This result may imply that the two types of movements differently utilize visual error information to update the states of motor learning processes. To investigate how the visual error modifies the subsequent rhythmic movements by a system identification technique, we had 8 participants perform rhythmic out-and-back reaching movements (the duration of one cycle, ∼ 400 ms) in the presence of visuomotor rotations whose magnitude varied randomly from cycle to cycle. The identified model revealed that the motor learning processes used the error information of up to 5 cycles in the past. Furthermore, it successfully reproduced the learning curve with higher plateau and slower time constant obtained in our previous study applying a constant 30◦ counterclockwise (CCW) rotation. Thus, making reference to the errors in a number of previous cycles may contaminate the learning processes of rhythmic movements. If it is true, then providing visual feedback intermittently can enhance the performance of the motor learning, especially when it is provided once every 5 cycles. To test this possibility, 43 participants were asked to adapt to 30◦ CCW rotation in one of the following 4 conditions: the visual feedback of the hand position was provided for all cycles (CON condition (n = 15)) and for only once every 2, 3, or 5 cycles (INT2 (n = 8), INT3 (n = 5), and INT5 (n = 15) conditions, respectively). The motor learning performance was not different from that in CON condition in INT2 and INT3 conditions, but significantly enhanced in INT5 condition, suggesting that visual error information provided within 2 s (i.e., 5 cycles x 400 ms) after a cycle would have harmful effects on the correction of the motor command in the subsequent cycles. doi:10.1016/j.neures.2010.07.226
O2-9-4-4 Topographic organization of commissural connections between the two superior colliculi and their functional roles for generating horizontal and vertical Saccades Mayu Takahashi , Yuriko Sugiuchi, Yoshikazu Shinoda Department of Systems Neurophysiology, Tokyo Medical and Dental University, Tokyo The pathway that interconnects the two superior colliculi (SCs) is considered to be important for visual-orienting behavior. Our electrophysiological study indicated that medial tectoreticular neurons (TRNs) in the rostral SC received strong commissural excitation from the medial part of the opposite rostral SC, whereas lateral TRNs received strong excitation from its lateral part, and medial and lateral TRNs received strong inhibition from the lateral and medial part of the opposite rostral SC, respectively. To provide morphological evidence for these electrophysiological findings, we examined tectal distribution of commissural excitatory and inhibitory neurons in the cat SC by injecting tracers into various parts of the SC, and the Forel’s field H (FFH). Double-labelling with GABA and gold particle-conjugated WGA -HRP (GP) was used to identify commissural neurons as GABAergic. Caudal SC injection labeled small-sized GABA-positive neurons (<200 m2 ) only in the opposite rostral SC, whereas rostral SC injection labeled medium-sized GABA-negative (200–700 m2 ) and small-sized commissural neurons in the opposite rostral SC. Lateral SC injection labeled small GABAergic neurons in the medial part of the opposite SC and non-GABAergic medium-sized neurons in its lateral part, whereas medial SC injection labeled small GABAergic neurons in the lateral part of the opposite SC and non-GABAergic medium-sized neurons in its medial part. Many of these medium-sized commissural neurons were TRNs projecting to the ipsilateral FFH with commissural collaterals to the opposite SC. These results provided morphological evidence to support that mirrorsymmetric excitation between medial - medial and lateral - lateral parts of the SCs plays an important role in conjugate upward and downward vertical saccades, respectively, and the medial SC representing upward saccades is
Ryuzo Shingai 1 , Hisanori Takahashi 1 , Yuishi Iwasaki 2 , Tokumitsu Wakabayashi 1 , Tarou Ogurusu 1 1
Dept of Applied Chemistry and Bioengineering, Iwate University 2 Faculty of Engineering, Ibaraki University, Hitachi, Japan To estimate functions of the nervous system of C. elegans in behavioral states, we constructed a neural network model that regulates chemotaxis and thermotaxis behaviors. Synaptic excitatory/inhibitory properties were assigned to be consistent to those predicted in published articles, and the excitatory/inhibitory properties of other synapses were assigned such that when thermal/chemical stimuli are given to sensory neurons, the interneurons which determine forward/backward movement show proper potential changes. Several interneurons and motor neurons in the obtained network showed specific patterns of excitatory or inhibitory responses to stimuli which were given simultaneously to different sensory neurons. We will also discuss the response of the circuit when noisy stimulus is input to the sensory neuron. doi:10.1016/j.neures.2010.07.228
O2-10-1-2 Multi-physical full-scale simulation for neuronal morphogenesis Seigo Nonaka , Naoki Honda, Shin Ishii Graduate School of Informatics, Kyoto University During embryonic development, cells differentiate to various types with specific morphologies which correspond to cellular functions. For examples, motile cells have structures of lamellipodia and filopodia and neurons are prominently polarized with axon and dendrites.The cellular morphogenesis is a complicated phenomenon, during which a cell receives extracellular signals and processes those through intracellular signal transduction, which controls the cell shape by regulating the reorganization of cytoskeleton such as actin filaments (F-actin) and microtubules. Although microscopic properties of cytoskeleton such as (de-)polymerization, capping and branching have been identified, filament-based understanding for macroscopic morphogenesis remains largely unclear.To fill in this hierarchical gap between microand macro-scopic phenomena, we constructed a multi-physical simulator for dynamics of cellular morphology, which is a system of reaction-diffusion of regulating molecules, F-actin and plasma membrane. In this simulation, the reaction-diffusion field and the membrane are discretized into multiple compartments and nodes, respectively. A F-actin is represented as a line segment and generates driving force against the membrane based on the elastic-ratchet model. Using this simulator, we demonstrated chemotactic migration.For realistic simulation, there was a problem of computational cost, because of the large number (∼108 ) of F-actin expressed inside a cell. The most expensive calculation is the collision detection between F-actin and membrane nodes. To resolve this problem, we adopted parallelization technique (in computer science) to allocate the partial simulation processes related to F-actin to multiple CPUs so that the collision detection is performed independently on each CPU. This parallelization successfully accelerated the run-speed almost linearly to the number of CPUs in some conditions. We also report some additional biological applications. doi:10.1016/j.neures.2010.07.229
O2-10-1-3 Prominent features of layer-specific in vivo activity arise from the structure of the cortical microcircuit Tobias C. Potjans 1,2 , Markus Diesmann 1,3 1
Brain and Neural Systems Team, RIKEN CSRP, Wako, Japan 2 Institute of Neurosciences and Medicine, Research Center Juelich, Germany 3 RIKEN Brain Science Institute, Wako, Japan The layer-specific structure of neuronal microcircuits has been hypothesized to play a crucial part in brain function. In the past decade, detailed connectivity maps of the local cortical network have been assembled (Binzegger et al., 2004, Thomson and Lamy, 2007) and cell-type specific recordings revealed the neuronal activity in vivo (de Kock and Sakmann, 2009; Sakata and Harris, 2009). The relationship of prominent connectivity features and the experimentally observed activity is nevertheless elusive.