Automation Concept for Electrically Excited LV Synchronous Motor: Implementation into AC500 Programmable Logic Environment

This bachelor’s thesis is a part of the research project realized in the summer 2011 in Lappeenranta University of Technology. The goal of the project was to develop an automation concept for controlling the electrically excited synchronous motor. Thesis concentrates on the implementation of the automation concept into the ABB’s AC500 programmable logic enviroment. The automation program was developed as a state machine with the ABB’s PS501 Control Builder software. For controlling the automation program is developed a fieldbus control and with CodeSys Visualization Tool a local control with control panel. The fieldbus control is done to correspond the ABB drives communication profile and the local control is implemented with a function block which feeds right control words into the statemachine. A field current control of the synchronous motor is realized as a method presented in doctoral thesis of Olli Pyrhönen (Pyrhönen 1998). The Method combines stator flux and torque based openloop control and power factor based feedback control.

JNK regulates dendrite and spine architecture in the central nervous system influencing spatial learning and motor tasks

JNK1 is a MAP-kinase that has proven a significant player in the central nervous system. It regulates brain development and the maintenance of dendrites and axons. Several novel phosphorylation targets of JNK1 were identified in a screen performed in the Coffey lab. These proteins were mainly involved in the regulation of neuronal cytoskeleton, influencing the dynamics and stability of microtubules and actin. These structural proteins form the dynamic backbone for the elaborate architecture of the dendritic tree of a neuron. The initiation and branching of the dendrites requires a dynamic interplay between the cytoskeletal building blocks. Both microtubules and actin are decorated by associated proteins which regulate their dynamics. The dendrite-specific, high molecular weight microtubule associated protein 2 (MAP2) is an abundant protein in the brain, the binding of which stabilizes microtubules and influences their bundling. Its expression in non-neuronal cells induces the formation of neurite-like processes from the cell body, and its function is highly regulated by phosphorylation. JNK1 was shown to phosphorylate the proline-rich domain of MAP2 in vivo in a previous study performed in the group. Here we verify three threonine residues (T1619, T1622 and T1625) as JNK1 targets, the phosphorylation of which increases the binding of MAP2 to microtubules. This binding stabilizes the microtubules and increases process formation in non-neuronal cells. Phosphorylation-site mutants were engineered in the lab. The non-phosphorylatable mutant of MAP2 (MAP2- T1619A, T1622A, T1625A) in these residues fails to bind microtubules, while the pseudo-phosphorylated form, MAP2- T1619D, T1622D, Thr1625D, efficiently binds and induces process formation even without the presence of active JNK1. Ectopic expression of the MAP2- T1619D, T1622D, Thr1625D in vivo in mouse brain led to a striking increase in the branching of cortical layer 2/3 (L2/3) pyramidal neurons, compared to MAP2-WT. The dendritic complexity defines the receptive field of a neuron and dictates the output to the postsynaptic cells. Previous studies in the group indicated altered dendrite architecture of the pyramidal neurons in the Jnk1-/- mouse motor cortex. Here, we used Lucifer Yellow loading and Sholl analysis of neurons in order to study the dendritic branching in more detail. We report a striking, opposing effect in the absence of Jnk1 in the cortical layers 2/3 and 5 of the primary motor cortex. The basal dendrites of pyramidal neurons close to the pial surface at L2/3 show a reduced complexity. In contrast, the L5 neurons, which receive massive input from the L2/3 neurons, show greatly increased branching. Another novel substrate identified for JNK1 was MARCKSL1, a protein that regulates actin dynamics. It is highly expressed in neurons, but also in various cancer tissues. Three phosphorylation target residues for JNK1 were identified, and it was demonstrated that their phosphorylation reduces actin turnover and retards migration of these cells. Actin is the main cytoskeletal component in dendritic spines, the site of most excitatory synapses in pyramidal neurons. The density and gross morphology of the Lucifer Yellow filled dendrites were characterized and we show reduced density and altered morphology of spines in the motor cortex and in the hippocampal area CA3. The dynamic dendritic spines are widely considered to function as the cellular correlate during learning. We used a Morris water maze to test spatial memory. Here, the wild-type mice outperformed the knock-out mice during the acquisition phase of the experiment indicating impaired special memory. The L5 pyramidal neurons of the motor cortex project to the spinal cord and regulate the movement of distinct muscle groups. Thus the altered dendrite morphology in the motor cortex was expected to have an effect on the input-output balance in the signaling from the cortex to the lower motor circuits. A battery of behavioral tests were conducted for the wild-type and Jnk1-/- mice, and the knock-outs performed poorly compared to wild-type mice in tests assessing balance and fine motor movements. This study expands our knowledge of JNK1 as an important regulator of the dendritic fields of neurons and their manifestations in behavior.

Effects of age on learning a spatial motor task in younger and older adults individualizing their knowledge of results schedule

Self-controlled KR practice has revealed that providing participants the opportunity to control their KR is superior for motor learning compared to participants replicating the KR schedule of a self-control participant, without the choice (e.g., yoked). The purpose of the present experiment was two-fold. First, to examine the utility of a self-controlled KR schedule for learning a spatial motor task in younger and older adults and second, to determine whether a self-controlled KR schedule facilitates an increased ability to estimate one’s performance in retention and transfer. Twenty younger adults and 20 older adults practiced in either the self-control or yoked condition and were required to push and release a slide along a confined pathway using their non-dominant hand to a target distance. The retention data revealed that as a function of age, a self-controlled KR schedule facilitated superior retention performance and performance estimations in younger adults compared to their yoked counterparts.

Effects of Proactive and Retroactive Augmented Information on Physiological Responses in Learning a Novel Motor Skill

Previous research has demonstrated superior learning by participants presented with augmented task information retroactively versus proactively (Patterson & Lee, 2008; 2010). Theoretical explanations of these findings are related to the cognitive effort invested by participants during motor skill acquisition. The present study extended previous research by utilizing the physiological index, power spectral analysis of heart rate variability, previously shown to be sensitive to the degree of cognitive effort invested during the performance of a motor task (e.g., increase cognitive effort results in increased LF/HF ratio). Participants were required to learn 18 different key-pressing sequences. As expected, the proactive condition demonstrated superior RS during acquisition, with the retroactive condition demonstrating superior RS during retention. Measures of LF/HF ratio indicated the retroactive participants were investing significantly less cognitive effort in the retention period compared to the proactive participants (p< .05) as a function of learning.

Examining peer-controlled KR schedules during the learning of a movement-timing task as a function of task experience.

Learners can be provided with feedback in the form of knowledge of results (KR), under self-controlled and peer-controlled schedules. Recently, McRae, Hansen, and Patterson (2015), identified that inexperienced peers can provide KR that can facilitate motor skill acquisition. However, it is currently unknown whether previous task experience differentially impacts how peers present learners with KR and whether this KR impacts motor skill acquisition. In the present study, participants were randomly assigned to become inexperienced peer facilitators, learners with an inexperienced peer, learners with self-control who later became experienced peers, learners with an experienced peer, or learners in a control group. During acquisition learners completed a serial-timing task with a goal of 2500ms and returned approximately twenty four hours later for a delayed retention, time transfer, and pattern transfer test. We predicted that during the delayed tests, learners with self-control would outperform all other groups. Furthermore, we predicted that learners who received KR from experienced peers would outperform learners who received KR from inexperienced peers. However, our results indicated that participants who received peer-controlled and self-controlled KR schedules learned the task in an equivalent manner. Thus, our results are novel as they identify that inexperienced peers can provide KR that is as effective as KR provided by experienced peers and KR requested under self-controlled conditions.

Intrahemispheric dysfunction in primary motor cortex without corpus callosum: a transcranial magnetic stimulation study

Affiliation: Département de Psychologie, Université de Montréal

Src family kinases are required for limb trajectory selection by spinal motor axons

Signal relay by guidance receptors at the axonal growth cone is a process essential for the assembly of a functional nervous system. We investigated the in vivo function of Src family kinases (SFKs) as growth cone guidance signaling intermediates in the context of spinal lateral motor column (LMC) motor axon projection toward the ventral or dorsal limb mesenchyme. Using in situ mRNA detection we determined that Src and Fyn are expressed in LMC motor neurons of chick and mouse embryos at the time of limb trajectory selection. Inhibition of SFK activity by C-terminal Src kinase (Csk) overexpression in chickLMCaxons using in ovo electroporation resulted inLMC axons selecting the inappropriate dorsoventral trajectory within the limb mesenchyme, with medial LMC axon projecting into the dorsal and ventral limb nerve with apparently random incidence. We also detected LMC axon trajectory choice errors in Src mutant mice demonstrating a nonredundant role for Src in motor axon guidance in agreement with gain and loss of Src function in chickLMCneurons which led to the redirection ofLMCaxons. Finally, Csk-mediated SFK inhibition attenuated the retargeting ofLMCaxons caused by EphA or EphB over-expression, implying the participation of SFKs in Eph-mediated LMC motor axon guidance. In summary, our findings demonstrate that SFKs are essential for motor axon guidance and suggest that they play an important role in relaying ephrin:Eph signals that mediate the selection of motor axon trajectory in the limb.

Bcl-xL regulation and function in cell cycle checkpoints and progression

Quelques évidences suggèrent que Bcl-xL, un membre anti-apoptotique de la famille Bcl-2, possède également des fonctions au niveau du cycle cellulaire et de ses points-contrôle. Pour étudier la régulation et fonction de Bcl-xL au cours du cycle cellulaire, nous avons généré et exprimé dans des cellules humaines une série de mutants de phosphorylation incluant Thr41Ala, Ser43Ala, Thr47Ala, Ser49Ala, Ser56Ala, Ser62Ala et Thr115Ala. L'analyse de cette série de mutants révèle que les cellules exprimant Bcl-xL(Ser62Ala) sont moins stables au point-contrôle G2 du cycle cellulaire comparées aux cellules exprimant le type sauvage ou les autres mutants de phosphorylation incluant Thr41Ala, Ser43Ala, Thr47Ala, Ser56Ala et Thr115Ala. Les études de cinétiques de phosphorylation et de localisation de phospho-Bcl-xL(Ser62) dans des cellules synchronisées et suite à l'activation du point-contrôle en G2 médié par l'étoposide (VP16), nous indiquent que phospho-Bcl-xL(Ser62) migre dans les corps nucléolaires durant l'arrêt en G2 dans les cellules exposées au VP16. Une série d'expériences incluant des essais kinase in vitro, l'utilisation d'inhibiteurs pharmacologiques et d'ARN interférant, nous révèlent que Polo kinase 1 (PLK1) et MAPK9/JNK2 sont les protéines kinase impliquées dans la phosphorylation de Bcl-xL(Ser62), et pour son accumulation dans les corps nucléolaires pendant le point-contrôle en G2. Nos résultats indiquent que durant le point-contrôle en G2, phospho-Bcl-xL(Ser62) se lie et se co-localise avec CDK1(CDC2), le complexe cycline-kinase qui contrôle l'entrée en mitose. Nos résultats suggèrent que dans les corps nucléolaires, phospho-Bcl-xL(Ser62) stabilise l'arrêt en G2 en séquestrant CDK1(CDC2) pour retarder l'entrée en mitose. Ces résultats soulignent également que les dommages à l'ADN influencent la composition des corps nucléolaires, structure nucléaire qui émerge maintenant comme une composante importante de la réponse aux dommages à l'ADN. Dans une deuxième étude, nous décrivons que les cellules exprimant le mutant de phosphorylation Bcl-xL(Ser62Ala) sont également plus stables au point-contrôle de l'assemblage du fuseau de la chromatine (SAC) suite à une exposition au taxol, comparées aux cellules exprimant le type sauvage ou d'autres mutants de phosphorylation de Bcl-xL, incluant Thr41Ala, Ser43Ala, Thr47Ala, Ser56Ala. Cet effet est indépendent de la fonction anti-apoptotique de Bcl-xL. Bcl-xL(Ser62) est fortement phosphorylé par PLK1 et MAPK14/SAPKp38α à la prométaphase, la métaphase et à la frontière de l'anaphase, et déphosphorylé à la télophase et la cytokinèse. Phospho-Bcl-xL(Ser62) se trouve dans les centrosomes avec γ-tubuline, le long du fuseau mitotique avec la protéine moteure dynéine et dans le cytosol mitotique avec des composantes du SAC. Dans des cellules exposées au taxol, phospho-Bcl-xL(Ser62) se lie au complexe inhibiteur CDC20/MAD2/BUBR1/BUB3, alors que le mutant Bcl-xL(Ser62Ala) ne se lie pas à ce complexe. Ces résultats indiquent que durant le SAC, la phosphorylation de Bcl-xL(Ser62) accélère la résolution du SAC et l'entrée des cellules en anaphase. Des expériences bloquant l'expression de Bcl-xL révèlent ègalement un taux très élevé de cellules tétraploïdes et binuclées après un traitement au nocodazole, consistant avec une fonction de Bcl-xL durant la mitose et dans la stabilité génomique. Dans la troisième étude, l'analyse fonctionnelle de cette série de mutants de phosphorylation indique également que les cellules exprimant Bcl-xL(Ser49Ala) sont moins stables durant le point-contrôle G2 et entre en cytokinèse plus lentement dans des cellules exposées aux inhibiteurs de la polymérisation/dépolymérisation des tubulines, composantes des microtubules. Ces effets de Bcl-xL(Ser49Ala) sont indépendents de sa fonction anti-apoptotique. La phosphorylation de Bcl-xL(Ser49) est dynamique au cours du cycle cellulaire. Dans des cellules synchronisées, Bcl-xL(Ser49) est phosphorylé en phase S et G2, déphosphorylé à la prométaphase, la métaphase et à la frontière de l'anaphase, et re-phosphorylé durant la télophase et la cytokinèse. Au cours du point-contrôle G2 induit par les dommages à l'ADN, un pool important de phospho-Bcl-xL(Ser49) se trouve aux centrosomes, un site important pour la régulation de l'entrée en mitose. Durant la télophase et la cytokinèse, phospho-Bcl-xL(Ser49) se trouve le long des microtubules avec la protéine moteure dynéine et dans le cytosol mitotique. Finalement, nos résultats suggèrent que PLK3 est responsable de la phosphorylation de Bcl-xL(Ser49), une protéine kinase impliquée pour l'entrée des cellules en mitose et pour la progression de la mitose jusqu'à la division cellulaire.

Observational learning of motor skills : Looking for optimal models

L’observation d’un modèle pratiquant une habileté motrice promeut l’apprentissage de l’habileté en question. Toutefois, peu de chercheurs se sont attardés à étudier les caractéristiques d’un bon modèle et à mettre en évidence les conditions d’observation pouvant optimiser l’apprentissage. Dans les trois études composant cette thèse, nous avons examiné les effets du niveau d’habileté du modèle, de la latéralité du modèle, du point de vue auquel l’observateur est placé, et du mode de présentation de l’information sur l’apprentissage d’une tâche de timing séquentielle composée de quatre segments. Dans la première expérience de la première étude, les participants observaient soit un novice, soit un expert, soit un novice et un expert. Les résultats des tests de rétention et de transfert ont révélé que l’observation d’un novice était moins bénéfique pour l’apprentissage que le fait d’observer un expert ou une combinaison des deux (condition mixte). Par ailleurs, il semblerait que l’observation combinée de modèles novice et expert induise un mouvement plus stable et une meilleure généralisation du timing relatif imposé comparativement aux deux autres conditions. Dans la seconde expérience, nous voulions déterminer si un certain type de performance chez un novice (très variable, avec ou sans amélioration de la performance) dans l’observation d’une condition mixte amenait un meilleur apprentissage de la tâche. Aucune différence significative n’a été observée entre les différents types de modèle novices employés dans l’observation de la condition mixte. Ces résultats suggèrent qu’une observation mixte fournit une représentation précise de ce qu’il faut faire (modèle expert) et que l’apprentissage est d’autant plus amélioré lorsque l’apprenant peut contraster cela avec la performance de modèles ayant moins de succès. Dans notre seconde étude, des participants droitiers devaient observer un modèle à la première ou à la troisième personne. L’observation d’un modèle utilisant la même main préférentielle que soi induit un meilleur apprentissage de la tâche que l’observation d’un modèle dont la dominance latérale est opposée à la sienne, et ce, quel que soit l’angle d’observation. Ce résultat suggère que le réseau d’observation de l’action (AON) est plus sensible à la latéralité du modèle qu’à l’angle de vue de l’observateur. Ainsi, le réseau d’observation de l’action semble lié à des régions sensorimotrices du cerveau qui simulent la programmation motrice comme si le mouvement observé était réalisé par sa propre main dominante. Pour finir, dans la troisième étude, nous nous sommes intéressés à déterminer si le mode de présentation (en direct ou en vidéo) influait sur l’apprentissage par observation et si cet effet est modulé par le point de vue de l’observateur (première ou troisième personne). Pour cela, les participants observaient soit un modèle en direct soit une présentation vidéo du modèle et ceci avec une vue soit à la première soit à la troisième personne. Nos résultats ont révélé que l’observation ne diffère pas significativement selon le type de présentation utilisée ou le point de vue auquel l’observateur est placé. Ces résultats sont contraires aux prédictions découlant des études d’imagerie cérébrale ayant montré une activation plus importante du cortex sensorimoteur lors d’une observation en direct comparée à une observation vidéo et de la première personne comparée à la troisième personne. Dans l’ensemble, nos résultats indiquent que le niveau d’habileté du modèle et sa latéralité sont des déterminants importants de l’apprentissage par observation alors que le point de vue de l’observateur et le moyen de présentation n’ont pas d’effets significatifs sur l’apprentissage d’une tâche motrice. De plus, nos résultats suggèrent que la plus grande activation du réseau d’observation de l’action révélée par les études en imagerie mentale durant l’observation d’une action n’induit pas nécessairement un meilleur apprentissage de la tâche.

Withania somnitera and withanolide a mediated restoration of AMPA and NMDA receptor function in pilocarpine induced temporal lobe epilepsy

The onset of spontaneous seizures triggers a cascade of molecular and cellular events that eventually leads to neuronal injury and cognitive decline. The present study investigated the effect of Withania somnifera (WS) root extract and Withanolide A (WA) in restoring behavioural deficit by inhibiting oxidative stress induced alteration in glutamergic neurotransmission. The subdued performance in behavioural tests shows impaired motor coordination and memory. Histopathological investigations revealed significant neuronal loss in hippocampus of epileptic rats indicating glutamate mediated excitotoxicity. The treatment with WS and WA restored behavioural deficit and ameliorated neuronal loss. An altered redox homeostasis leading to oxidative stress is a hallmark of TLE. The antioxidant potential was afflicted in epileptic rats, evident from altered activity of SOD and CAT, down regulation of SOD and GPX expression and enhanced lipid peroxidation. The antioxidant property of WS and WA restored altered antioxidant capacity. Alteration in GDH activity and down regulation of GLAST expression resulted in enhanced glutamate content in the brain regions. The metabolism of glutamate was altered in the form of down regulated GAD expression. The alteration in synthesis, transport and metabolism resulted in further increase of the glutamate concentration at the synapse leading to glutamate mediated excitotoxicity. The decreased NMDA and AMPA receptor binding and down regulated NMDA R1, NMDA 2B and AMPA (GluR2) mRNA expression indicated altered glutamergic receptor function. The treatment with WS and WA reversed altered glutamergic receptor function, synthesis, transport and metabolism. The enhanced levels of second messenger IP3 responsible for Ca2+ mediated toxicity was reversed after treatment with WS and WA. Neurotoxics concentration of glutamate resulted in up regulation of pro apoptotic factors Bax and Caspase 8 and down regulation of anti apoptotic factor Akt resulting in neuronal death. The treatment with WS and WA resulted in activation of Akt and down regulation of Bax and caspase 8 leading to blocking of apoptotic pathway. The treatment with WS and WA resulted in reduced seizure frequency and amelioration of associated alterations suggesting the therapeutic role of Withania somnifera in temporal lobe epilepsy

Prefrontal cortical-ventral striatal interactions involved in affective modulation of attentional performance: implications for corticostriatal circuit function

Anatomically segregated systems linking the frontal cortex and the striatum are involved in various aspects of cognitive, affective, and motor processing. In this study, we examined the effects of combined unilateral lesions of the medial prefrontal cortex (mPFC) and the core subregion of the nucleus accumbens (AcbC) in opposite hemispheres (disconnection) on a continuous performance, visual attention test [five-choice serial reaction-time task (5CSRTT)]. The disconnection lesion produced a set of specific changes in performance of the 5CSRTT, resembling changes that followed bilateral AcbC lesions while, in addition, comprising a subset of the behavioral changes after bilateral mPFC lesions previously reported using the same task. Specifically, both mPFC/AcbC disconnection and bilateral AcbC lesions markedly affected aspects of response control related to affective feedback, as indexed by perseverative responding in the 5CSRTT. These effects were comparable, although not identical, to those in animals with either bilateral AcbC or mPFC/AcbC disconnection lesions. The mPFC/AcbC disconnection resulted in a behavioral profile largely distinct from that produced by disconnection of a similar circuit described previously, between the mPFC and the dorsomedial striatum, which were shown to form a functional network underlying aspects of visual attention and attention to action. This distinction provides an insight into the functional specialization of corticostriatal circuits in similar behavioral contexts.

The effect of the GENTLE/s robot-mediated therapy system on arm function after stroke

Objective: To evaluate the effect of robot-mediated therapy on arm dysfunction post stroke. Design: A series of single-case studies using a randomized multiple baseline design with ABC or ACB order. Subjects (n = 20) had a baseline length of 8, 9 or 10 data points. They continued measurement during the B - robot-mediated therapy and C - sling suspension phases. Setting: Physiotherapy department, teaching hospital. Subjects: Twenty subjects with varying degrees of motor and sensory deficit completed the study. Subjects attended three times a week, with each phase lasting three weeks. Interventions: In the robot-mediated therapy phase they practised three functional exercises with haptic and visual feedback from the system. In the sling suspension phase they practised three single-plane exercises. Each treatment phase was three weeks long. Main measures: The range of active shoulder flexion, the Fugl-Meyer motor assessment and the Motor Assessment Scale were measured at each visit. Results: Each subject had a varied response to the measurement and intervention phases. The rate of recovery was greater during the robot-mediated therapy phase than in the baseline phase for the majority of subjects. The rate of recovery during the robot-mediated therapy phase was also greater than that during the sling suspension phase for most subjects. Conclusion: The positive treatment effect for both groups suggests that robot-mediated therapy can have a treatment effect greater than the same duration of non-functional exercises. Further studies investigating the optimal duration of treatment in the form of a randomized controlled trial are warranted.

Dynamic modulation of human motor activity when observing actions

Previous studies have demonstrated that when we observe somebody else executing an action many areas of our own motor systems are active. It has been argued that these motor activations are evidence that we motorically simulate observed actions; this motoric simulation may support various functions such as imitation and action understanding. However, whether motoric simulation is indeed the function of motor activations during action observation is controversial, due to inconsistency in findings. Previous studies have demonstrated dynamic modulations in motor activity when we execute actions. Therefore, if we do motorically simulate observed actions, our motor systems should also be modulated dynamically, and in a corresponding fashion, during action observation. Using magnetoencephalography (MEG), we recorded the cortical activity of human participants while they observed actions performed by another person. Here, we show that activity in the human motor system is indeed modulated dynamically during action observation. The finding that activity in the motor system is modulated dynamically when observing actions can explain why studies of action observation using functional magnetic resonance imaging (fMRI) have reported conflicting results, and is consistent with the hypothesis that we motorically simulate observed actions.

Expression and function of the bile acid receptor GpBAR1 (TGR5) in the murine enteric nervous system

BACKGROUND: Bile acids (BAs) regulate cells by activating nuclear and membrane-bound receptors. G protein coupled bile acid receptor 1 (GpBAR1) is a membrane-bound G-protein-coupled receptor that can mediate the rapid, transcription-independent actions of BAs. Although BAs have well-known actions on motility and secretion, nothing is known about the localization and function of GpBAR1 in the gastrointestinal tract. METHODS: We generated an antibody to the C-terminus of human GpBAR1, and characterized the antibody by immunofluorescence and Western blotting of HEK293-GpBAR1-GFP cells. We localized GpBAR1 immunoreactivity (IR) and mRNA in the mouse intestine, and determined the mechanism by which BAs activate GpBAR1 to regulate intestinal motility. KEY RESULTS: The GpBAR1 antibody specifically detected GpBAR1-GFP at the plasma membrane of HEK293 cells, and interacted with proteins corresponding in mass to the GpBAR1-GFP fusion protein. GpBAR1-IR and mRNA were detected in enteric ganglia of the mouse stomach and small and large intestine, and in the muscularis externa and mucosa of the small intestine. Within the myenteric plexus of the intestine, GpBAR1-IR was localized to approximately 50% of all neurons and to >80% of inhibitory motor neurons and descending interneurons expressing nitric oxide synthase. Deoxycholic acid, a GpBAR1 agonist, caused a rapid and sustained inhibition of spontaneous phasic activity of isolated segments of ileum and colon by a neurogenic, cholinergic and nitrergic mechanism, and delayed gastrointestinal transit. CONCLUSIONS & INFERENCES: G protein coupled bile acid receptor 1 is unexpectedly expressed in enteric neurons. Bile acids activate GpBAR1 on inhibitory motor neurons to release nitric oxide and suppress motility, revealing a novel mechanism for the actions of BAs on intestinal motility.

Intermittently-visual tracking experiments reveal the roles of error-correction and predictive mechanisms in the human visual-motor control system

Prediction mechanism is necessary for human visual motion to compensate a delay of sensory-motor system. In a previous study, “proactive control” was discussed as one example of predictive function of human beings, in which motion of hands preceded the virtual moving target in visual tracking experiments. To study the roles of the positional-error correction mechanism and the prediction mechanism, we carried out an intermittently-visual tracking experiment where a circular orbit is segmented into the target-visible regions and the target-invisible regions. Main results found in this research were following. A rhythmic component appeared in the tracer velocity when the target velocity was relatively high. The period of the rhythm in the brain obtained from environmental stimuli is shortened more than 10%. The shortening of the period of rhythm in the brain accelerates the hand motion as soon as the visual information is cut-off, and causes the precedence of hand motion to the target motion. Although the precedence of the hand in the blind region is reset by the environmental information when the target enters the visible region, the hand motion precedes the target in average when the predictive mechanism dominates the error-corrective mechanism.