Orientation of the opposition axis in mentally simulated grasping

Five normal subjects were tested in a simulated grasping task. A cylindrical container filled with water was placed on the center of a horizontal monitor screen. Subjects used a precision grip formed by the thumb and index finger of their right hand. After a preliminary run during which the container was present, it was replaced by an image of the upper surface of the cylinder appearing on the horizontal computer screen on which the real cylinder was placed during the preliminary run. In each trial the image was marked with two contact points which defined an opposition axis in various orientations with respect to the frontal plane. The subjects’ task consisted, once shown a stimulus, of judging as quickly as possible whether the previously experienced action of grasping the container full of water and pouring the water out would be easy, difficult or impossible with the fingers placed according to the opposition axis indicated on the circle. Response times were found to be longer for the grasps judged to be more difficult due to the orientation and position of the opposition axis. In a control experiment, three subjects actually performed the grasps with different orientations and positions of the opposition axis. The effects of these parameters on response time followed the same trends as during simulated movements. This result shows that simulated hand movements take into account the same biomechanical limitations as actually performed movements

A dissociation between real and simulated movements in Parkinson's disease

Subcortical lesions have been simultaneously implicated in both real and simulated movement deficits. However, the analysis of the simulated opposition axis in precision grasping reveals that, in individuals with idiopathic bilateral Parkinson's disease motor imagery is impaired and that execution of overt movements is spared. This constitutes the first lesion observation congruent with the anatomical and functional dichotomy between real and simulated movements seen in experimental studies. These results underline the modality-specific nature of motor imagery and show that subcortical damage differentially impacts on motor activity

A Simple Technique to Study Embodied Language Processes: The Grip-Force Sensor

Research in cognitive neuroscience has shown that brain structures serving perceptual, emotional, and motor processes are also recruited during the understanding of language when it refers to emotion, perception, and action. However, the exact linguistic and extra-linguistic conditions under which such language-induced activity in modality specific cortex is triggered are not yet well understood. The purpose of this study is to introduce a simple experimental technique that allows for the online measure of language-induced activity in motor structures of the brain. This technique consists in the use of a grip force sensor that captures subtle grip force variations while subjects listen to words and sentences. Since grip force reflects activity in motor brain structures, the continuous monitoring of force fluctuations provides a fine-grained estimation of motor activity across time. In other terms, this method allows for both the localization of the source of language-induced activity to motor brain structures and the high temporal resolution of the recorded data. To facilitate comparison of data to be collected with this tool, we present two experiments that describe in detail the technical set up, the nature of the recorded data, and analyses (including justification about data filtering and artifact rejection) that we applied. We also discuss how the tool could be used in other domains of behavioral research

Supplementary Motor Area: A view from the left hand of the grip force modulation in unimanual and bimanual symmetric task.

The grip force modulation (GFM) in relation to the linguistic stimulation has been correlated to the semantic decoding (Frak, Nazir, Goyette, Cohen, & Jeannerod, 2010) and the somatotopic representation of the words (Hauk, Johnsrude, & Pulvermüller, 2004). A network composed of the intraparietal area, Brodmann area 6, the Broca area and M1, in conjunction with their roles, have been discussed for their effect on the GFM of the right hand (RH) (Ramayya,Glasser, & Rilling, 2010; Stout & Chaminade, 2012; Tomasino & Rumiati, 2014). The Brodmann area 6 included the premotor area (PMA) and supplementary motor area (SMA). Both have been associated to planification of action (Pilgramm et al., 2016), and SMA is particularly active during bimanual mouvements (Naito, Morita, & Amemiya, 2016).The aim of this study is to provide a description of the GFM of the left hand (LH) between unimanual and bimanual grip. Compare it to the RH in both conditions in order to add some evidence for understanding the linguistic function processing in both hemispheres

Grip Force Reveals the Context Sensitivity of Language-Induced Motor Activity during “Action Words

Studies demonstrating the involvement of motor brain structures in language processing typically focus on \ud time windows beyond the latencies of lexical-semantic access. Consequently, such studies remain inconclusive regarding whether motor brain structures are recruited directly in language processing or through post-linguistic conceptual imagery. In the present study, we introduce a grip-force sensor that allows online measurements of language-induced motor activity during sentence listening. We use this tool to investigate whether language-induced motor activity remains constant or is modulated in negative, as opposed to affirmative, linguistic contexts. Our findings demonstrate that this simple experimental paradigm can be used to study the online crosstalk between language and the motor systems in an ecological and economical manner. Our data further confirm that the motor brain structures that can be called upon during action word processing are not mandatorily involved; the crosstalk is asymmetrically\ud governed by the linguistic context and not vice versa

Comparison study of sorting techniques in static data structure

To manage and organize large data is imperative in order to formulate the data analysis and data processing efficiency. Therefore, this paper investigates the set of sorting techniques to observe which technique to provide better efficiency. Five types of sorting techniques of static data structure, Bubble, Insertion, Selection with O(n2 ) complexity and Merge, Quick with O(n log n) complexity have been used and tested on four groups between (100–30000) of dataset. To validate the performance of sorting techniques, three performance metrics which are time complexity, execution time and size of dataset were used. All experimental setups were accomplished using simple linear regression. The experimental results illustrate that Quick sort is more efficiency than other sorting and Selection sort is more efficient than Bubble and Insertion in large data size using array. In addition, Bubble, Insertion and Selection have good performance for small data size using array thus, sorting technique with behaviour O(n log n) is more efficient than sorting technique with behaviour O(n2 ) using array

Mental imaging of motor activity in humans

Motor imagery corresponds to a subliminal activation of the motor system, a system that appears to be involved not only in producing movements, but also in imagining actions, recognising tools and learning by observation, as well as in understanding the behaviour of other people. Recent advances in the field include the use of techniques for mapping brain activity and probing cortical excitability, as well as observation of brain lesioned patients during imaging tasks; these advances provide new insights into the covert aspects of motor activity

Action relevance in linguistic context drives word-induced motor activity

Many neurocognitive studies on the role of motor structures in action-language processing have implicitly adopted a “dictionary-like” framework within which lexical meaning is constructed on the basis of an invariant set of semantic features. The debate has thus been centered on the question of whether motor activation is an integral part of the lexical semantics (embodied theories) or the result of a post-lexical construction of a situation model (disembodied theories). However, research in psycholinguistics show that lexical semantic processing and context-dependent meaning construction are narrowly integrated. An understanding of the role of motor structures in action-language processing might thus be better achieved by focusing on the linguistic contexts under which such structures are recruited. Here, we therefore analyzed online modulations of grip force while subjects listened to target words embedded in different linguistic contexts. When the target word was a hand action verb and when the sentence focused on that action (John signs the contract) an early increase of grip force was observed. No comparable increase was detected when the same word occurred in a context that shifted the focus toward the agent's mental state (John wants to sign the contract). There mere presence of an action word is thus not sufficient to trigger motor activation. Moreover, when the linguistic context set up a strong expectation for a hand action, a grip force increase was observed even when the tested word was a pseudo-verb. The presence of a known action word is thus not required to trigger motor activation. Importantly, however, the same linguistic contexts that sufficed to trigger motor activation with pseudo-verbs failed to trigger motor activation when the target words were verbs with no motor action reference. Context is thus not by itself sufficient to supersede an “incompatible” word meaning. We argue that motor structure activation is part of a dynamic process that integrates the lexical meaning potential of a term and the context in the online construction of a situation model, which is a crucial process for fluent and efficient online language comprehension

The role of sensation for hand function in children with cerebral palsy

This chapter reviews the importance of sensations such as vision, as well as cutaneous sensibility and proprioception for the refined motor control of the hand. Intact sensory receptors provide input needed for modulation and adjustment of movements to ensure that they are accurate and smooth. Cerebral palsy is a non-progressive disorder of movement and posture, often accompanied by disturbances of sensation. For rehabilitation specialists evaluating children with CP in the clinical setting, it is essential that the potential influence of sensory impairments be considered, as it may impact on sensory-motor integration needed for refined hand movements to execute everyday tasks and activities. Therapeutic interventions may focus on maximizing tactile sensibility using sensory retraining and stimulation approaches, with the expectation that sensory input will improve and prehension patterns will become more precise. Conversely, capitalizing on more intact sensory modalities and use of adaptive strategies may be employed to enhance learning of functional hand skills, in spite of sensory-motor deficits. Evidence to support the effectiveness of either remediation or compensatory approaches is lacking, and needs to be addressed in future studies, so as to promote hand function needed to independently execute everyday self-care, school and leisure activities in children and youth with CP