1,721,012 research outputs found
Orienting movements in area 9 identified by long-train ICMS
No full textThe effect of intracortical microstimulation has been studied in several cortical areas from motor to sensory areas. The frontal pole has received particular attention, and several microstimulation studies have been conducted in the frontal eye field, supplementary eye field, and the premotor ear–eye field, but no microstimulation studies concerning area 9 are currently available in the literature. In the present study, to fill up this gap, electrical microstimulation was applied to area 9 in two macaque monkeys using long-train pulses of 500–700–800 and 1,000 ms, during two different experimental conditions: a spontaneous condition, while the animals were not actively fixating on a visual target, and during a visual fixation task. In these experiments, we identified backward ear movements, goal-directed eye movements, and the development of head forces. Kinematic parameters for ear and eye movements overlapped in the spontaneous condition, but they were different during the visual fixation task. In this condition, ear and eye kinematics have an opposite behavior: movement amplitude, duration, and maximal and mean velocities increase during a visual fixation task for the ear, while they decrease for the eye. Therefore, a top-down visual attention engagement could modify the kinematic parameters for these two effectors. Stimulation with the longest train durations, i.e., 800/1,000 ms, evokes not only the highest eye amplitude, but also a significant development of head forces. In this research article, we propose a new vision of the frontal oculomotor fields, speculating a role for area 9 in the control of goal-directed orienting behaviors and gaze shift control
Pilot Study in Youth Volleyball: Video Analysis as a Didactic Tool
No full textEf cacy of the spike is important in volleyball score and ef ciency of training process has a prior aim for coach, in the same time video analysis is used to purpose quantitative aspect of performance. Could be useful the use of performance as teaching method to improve single sport skills. The aim is to utilize this teaching methodology with visual feedback by video analysis to improve the technique model of spike. Methods is experimental and involve an under 21 women team, divided in control and experimental group, run of 10 training weeks while is going on the championship. Experimental group reviews itself by video without comments or helps of coach who evaluates speci c technical aspects of spike by speci c descriptors in check list of sport skill in presence of the athletes. The improvement of sports skills of control group is increased in minor percentage than of experimental group for difference of 12%. The different percentage could be attributed at the presence of the visual feedbacks in teaching training method. Data shows the future use of this tool in training and in physical education and not only for statistics or tactics scheme
Pilot Study in Youth Volleyball: Video Analysis as a Didactic Tool
No full textEf cacy of the spike is important in volleyball score and ef ciency of training process has a prior aim for coach, in the same time video analysis is used to purpose quantitative aspect of performance. Could be useful the use of performance as teaching method to improve single sport skills. The aim is to utilize this teaching methodology with visual feedback by video analysis to improve the technique model of spike. Methods is experimental and involve an under 21 women team, divided in control and experimental group, run of 10 training weeks while is going on the championship. Experimental group reviews itself by video without comments or helps of coach who evaluates speci c technical aspects of spike by speci c descriptors in check list of sport skill in presence of the athletes. The improvement of sports skills of control group is increased in minor percentage than of experimental group for difference of 12%. The different percentage could be attributed at the presence of the visual feedbacks in teaching training method. Data shows the future use of this tool in training and in physical education and not only for statistics or tactics scheme
A new field in monkey's frontal cortex: premotor ear-eye field (PEEF)
No full textIn macaque monkey, area 8B is cytoarchitectonically considered a transitional area between the granular Brodmann area 9, rostrally, and the rostral part of the dorsal agranular Brodmann area 6, caudally. As for electrophysiological data, microstimulation of area 8B evokes ear and/or eye movements; unit activity recording shows neurons encoding different auditory environmental stimuli and ear and/or eye movements. Moreover, visual attentive fixation modulates the discharge of auditory environmental neurons and auditory-motor neurons. As for anatomical data, area 8B is connected with auditory cortical areas, superior colliculus and cerebellum. Current functional and anatomical evidences support that area 8B is a specific Premotor Ear-Eye Field (PEEF) involved in auditory stimuli recognition and in orienting processes. In conclusion, we suggest that PEEF could play an important role in engaging the auditory spatial attention for the purpose of orienting eye and ear towards the sound source
Spatial anisotropy in the encoding of three-dimensional passive limb position by the spinocerebellum
No full textIn an earlier study, we found that the encoding of limb position in the sagittal plane across the population of spinocerebellar Purkinje cells was anisotropic with a preferential gradient along horizontal direction. The aim of this study was to extend to a three-dimensional (3D) workspace the analysis of the relationships between Purkinje cells activity and rat's forelimb spatial position. In anesthetized animals, the extracellular activity of 121 neurons was recorded while a robot passively placed the limb in 18 positions within a cubic workspace (3x3x3 cm). In order to characterize the relationship between spatial locations and Purkinje cell activity we performed a backward stepwise regression starting from a model with three independent variables representing the antero-posterior, the medial-lateral and the vertical axes of workspace. Regression analysis showed that the firing of most cells was modulated exclusively along the antero-posterior (25%) or the medial-lateral (38%) axis, while a small portion was related only to the vertical axis (8%), indicating a generalized nonuniform sensitivity of Purkinje cells to limb displacement in 3D space
Comparison of neuronal activities of external cuneate nucleus, spinocerebellar cortex and interpositus nucleus during passive movements of the rat's forelimb
No full textIn this paper we examined the neuronal activities of external cuneate nucleus, spinocerebellar Purkinje cells and interpositus nucleus during passive forelimb movements in anesthetized rats with the aim of identifying common or different patterns of activation across structures. By means of principal components analysis, we identified two main patterns of discharge which explained most of the dataset variance. One component characterized the movement-related activity of external cuneate and spinocerebellar cortical neurons, while the other reflected neuronal activity of the interpositus nucleus. We also found that both principal components were related to global forelimb kinematics but, while most of the variance of the activity of external cuneate cells and spinocerebellar Purkinje cells was explained by the limb axis orientation and orientation velocity, interpositus neurons' firing was best related to length and length velocity. This difference in the forelimb kinematics representation observed in external cuneate nucleus and spinocerebellar cortex compared with the interpositus nucleus is discussed with respect to the specific role that these structures may play also during active control of limb movements
Non-N-methyl-D-aspartate receptors mediate neocerebellar excitation at accessory oculomotor nuclei synapses of the rat
No full textThe nature of the receptor which mediates cerebellar-evoked monosynaptic excitations recorded from the accessory oculomotor nuclei (AON), i.e. the nucleus of posterior commissure, the nucleus of Darkschewitsch and the interstitial nucleus of Cajal, was studied in adult rats. Effects of exogenously applied excitatory amino acid (EAA) agonists N-methyl-D-aspartate (NMDA) and quisqualate (QUIS) and of selective NMDA receptor antagonist 2-amino-5-phosphonovaleric acid (2APV) and non-NMDA receptor antagonist 6,7-dinitroquinoxaline-2,3-dione (DNQX) were examined on both amino acid induced and synaptic excitation. Microiontophoretic application of NMDA and QUIS in the AON of the rat increases the neuronal discharge in a dose-dependent manner. These findings suggest that in the rat cells belonging to AON bear both NMDA and non-NMDA receptors. This result was confirmed by the fact that applications of 2APV selectively antagonized NMDA-induced responses without affecting those to QUIS, while DNQX blocked specifically the excitatory responses to QUIS and did not affect NMDA-mediated excitations. We did not observe any difference, between rats anesthetized with urethane and those anesthetized with halothane, with respect to capability of EAA agonists NMDA and QUIS to increase the AON cells activity and of EAA receptor antagonists 2APV and DNQX to abolish the NMDA-induced and the QUIS-induced effects, respectively. In addition, monosynaptic excitations induced by the stimulation of cerebellar lateral nucleus were abolished by microiontophoretic application of DNQX, but not of 2APV. This finding indicates that neocerebellar inputs activate specifically non-NMDA receptors of AON neurons
Orienting movements in area 9 identified by long-train ICMS
Full text linkThe effect of intracortical microstimulation has been studied in several cortical areas from motor to sensory areas. The frontal pole has received particular attention, and several microstimulation studies have been conducted in the frontal eye field, supplementary eye field, and the premotor ear-eye field, but no microstimulation studies concerning area 9 are currently available in the literature. In the present study, to fill up this gap, electrical microstimulation was applied to area 9 in two macaque monkeys using long-train pulses of 500-700-800 and 1,000 ms, during two different experimental conditions: a spontaneous condition, while the animals were not actively fixating on a visual target, and during a visual fixation task. In these experiments, we identified backward ear movements, goal-directed eye movements, and the development of head forces. Kinematic parameters for ear and eye movements overlapped in the spontaneous condition, but they were different during the visual fixation task. In this condition, ear and eye kinematics have an opposite behavior: movement amplitude, duration, and maximal and mean velocities increase during a visual fixation task for the ear, while they decrease for the eye. Therefore, a top-down visual attention engagement could modify the kinematic parameters for these two effectors. Stimulation with the longest train durations, i.e., 800/1,000 ms, evokes not only the highest eye amplitude, but also a significant development of head forces. In this research article, we propose a new vision of the frontal oculomotor fields, speculating a role for area 9 in the control of goal-directed orienting behaviors and gaze shift control
Cerebellar encoding of limb position
No full textIn this paper, we review single and multijoint studies that, over the years, have provided insight on the cerebellar encoding of limb spatial position. In particular, we present support to the idea that the cerebellum integrates signals from multiple sources to encode global limb parameters. Then, we highlight the result of recent studies that analyzed quantitatively the relationships between limb end-point position and cerebellar activity. These findings suggest that the cerebellum may share with other central sensory-motor structures an anisotropic representation of limb position characterized by a strong bias along the anteroposterior axis. Finally, we speculate that this anisotropy may also subtend an internal representation of limb mechanics
c-fos expression in the accessory oculomotor nuclei following neocerebellar stimulation
No full textThe present study was carried out to determine whether, in the rat, the electric activation of the projection from the cerebellar lateral nucleus (LN) to the accessory oculomotor nuclei (AON; nucleus of posterior commissure, nucleus of Darkschewitsch, interstitial nucleus of Cajal) is capable of inducing c-fos expression. In particular, we compared the effects of a continuous LN stimulation at low-frequency (tonic stimulation) with those induced by high frequency pulse trains (phasic stimulation). The observed results show that the stimulation of LN induces c-fos expression in a significant proportion of neurones in the contralateral AON. Phasic stimulation was slightly more effective than tonic stimulation in producing c-fos expression
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