Search results for " Movement"
showing 10 items of 1376 documents
Parafoveal previews and lexical frequency in natural reading: Evidence from eye movements and fixation-related potentials.
2019
Participants' eye movements and electroencephalogram (EEG) signal were recorded as they read sentences displayed according to the gaze-contingent boundary paradigm. Two target words in each sentence were manipulated for lexical frequency (high vs. low frequency) and parafoveal preview of each target word (identical vs. string of random letters vs. string of Xs). Eye movement data revealed visual parafoveal-on-foveal (PoF) effects, as well as foveal visual and orthographic preview effects and word frequency effects. Fixation-related potentials (FRPs) showed visual and orthographic PoF effects as well as foveal visual and orthographic preview effects. Our results replicated the early preview …
Evidence of a preprogrammed deactivation of the hamstring muscles for triggering rapid changes of posture in humans
1997
Normal subjects were asked to make rapid flexions of the legs from a stationary initial standing posture in a self-paced mode. Because this movement implicates a rapid change in posture, questions were asked about the type of central command which must include the rupture of the erect posture and the accomplishment of the goal directed movement. Movements of the different segments of the body were recorded and analyzed using the optoelectronic ELITE system. Electromyographic (EMG) activities of 8 muscles of the lower limb on one side were recorded, rectified and integrated. The time relationships of the different EMG signals (activation or deactivation) were analyzed with respect to selecte…
Human walking along a curved path. I. Body trajectory, segment orientation and the effect of vision.
2003
Task-related characteristics of gait and segment orientation during natural locomotion along a curved path have been described in order to gain insight into the neural organization of walking. The locomotor task implied continuous deviation from straight-ahead, thereby requiring continuous adjustment of body movement to produce and assist turn-related torques. Performance was compared to straight-ahead locomotion. Subjects easily reproduced both trajectories with eyes open (EO). The actual-to-required trajectory difference increased blindfolded (BF), more so during turning. Stride length was unchanged for the outer but decreased for the inner leg. The feet anticipated subsequent body rotati…
Influence of stimulus color on the control of reaching-grasping movements.
2001
This kinematic study aimed to determine whether color is a stimulus property involved in the control of reaching-grasping movements. Subjects reached and grasped a target-object, located either on the right or on the left of the subject's midline. A distractor, placed along the subject's midline, could be randomly presented. The colors, i.e., both chromaticity (red and green stimuli were presented) and lightness, of the target and distractor were varied in experiment 1. Only stimulus lightness and only stimulus chromaticity were varied in experiments 2 and 3, respectively. In experiment 4 subjects matched with their thumb and index finger the size of the target-stimuli presented in experime…
Visual distractors differentially interfere with the reaching and grasping components of prehension movements
1998
In the present study we addressed the issue of how an object is visually isolated from surrounding cues when a reaching-grasping (prehension) movement towards it is planned. Subjects were required to reach and grasp an object presented either alone or with a distractor. In five experiments, different degrees of elaboration of the distractor were induced by varying: (1) the position of the distractor (central or peripheral); (2) the time when the distractor was suppressed (immediately or delayed, with respect to stimulus presentation); and (3) the type of distractor analysis (implicit or explicit). In addition, we tested whether the possible effects of the distractor on reaching-grasping wer…
Training the Motor Cortex by Observing the Actions of Others During Immobilization
2014
International audience; Limb immobilization and nonuse are well-known causes of corticomotor depression. While physical training can drive the recovery from nonuse-dependent corticomotor effects, it remains unclear if it is possible to gain access to motor cortex in alternative ways, such as through motor imagery (MI) or action observation (AO). Transcranial magnetic stimulation was used to study the excitability of the hand left motor cortex in normal subjects immediately before and after 10 h of right arm immobilization. During immobilization, subjects were requested either to imagine to act with their constrained limb or to observe hand actions performed by other individuals. A third gro…
Emotional communication in the context of joint attention for food stimuli: Effects on attentional and affective processing
2014
Guided by distinct theoretical frameworks (the embodiment theories, shared-signal hypothesis, and appraisal theories), we examined the effects of gaze direction and emotional expressions (joy, disgust, and neutral) of virtual characters on attention orienting and affective reactivity of participants while they were engaged in joint attention for food stimuli contrasted by preference (disliked, moderately liked, and liked). The participants were exposed to videos of avatars looking at food and displaying facial expressions with their gaze directed either toward the food only or toward the food and participants consecutively. We recorded eye-tracking responses, heart rate, facial electromyogr…
Language and motor control.
2000
We investigated the possible influence of automatic word reading on processes of visuo-motor transformation. Subjects reached and grasped an object on which the following Italian words were printed: 'VICINO' (near) or 'LONTAN' (far) on an object either near or far from the agent (experiments 1, 2); PICCOLO (small) or 'GRANDE' (large) on either a small or a large object (experiment 4); and 'ALTO' (high) or 'BASSO' (low) on either a high or a low object (experiment 5). The kinematics of the initial phase of reaching-grasping was affected by the meaning of the printed words. Namely, subjects automatically associated the meaning of the word with the corresponding property of the object and acti…
Planning an action.
1997
The motor control of a sequence of two motor acts forming an action was studied in the present experiment. The two analysed motor acts were reaching-grasping an object (first target) and placing it on a second target of the same shape and size (experiment 1). The aim was to determine whether extrinsic properties of the second target (i.e. target distance) could selectively influence the kinematics of reaching and grasping. Distance, position and size of both targets were randomly varied across the experimental session. The kinematics of the initial phase of the first motor act, that is, velocity of reaching and hand shaping of grasping, were influenced by distance of the second target. No k…
Visual illusions and the control of children arm movements.
2001
The aim of the present study was to determine whether children like adults (Gentilucci M, Chieffi S, Daprati E, Saetti MC, Toni I. Visual illusion and action. Neuropsychologia 1996;34:369-76; Gentilucci M, Daprati E, Gangitano M, Toni I. Eye position tunes the contribution of allocentric and egocentric information to target localisation in human goal directed arm movements. Neurosci Lett 1997;222:123-6) are influenced by visual illusions when they transform visual information in motor command. Children and adults pointed to a shaft extremity of the Müller-Lyer configurations, as well as to an extremity of a control configuration. Movements were executed in two experimental conditions. In th…