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Motor Imagery (motor + imagery)

Distribution by Scientific Domains

Medical Sciences	50%

Selected Abstracts

Impaired motor imagery in patients with essential tremor: A case control study

MOVEMENT DISORDERS, Issue 4 2007
Yew-Long Lo MD
Abstract Motor imagery (MI), which refers to the process of mental representation of movements, has not been studied in patients with essential tremor (ET). We investigated the presence of impaired MI in ET patients compared with healthy controls. A group of drug-naive and nondemented ET patients and age-matched controls were studied using transcranial magnetic stimulation, while they were specifically instructed to try and imagine themselves performing two motor tasks. The various clinical and electrophysiological variables were evaluated and compared. Repeated measures ANOVA demonstrated a significant difference between ET patients and controls with respect to mean motor-evoked potential (MEP) amplitudes (F(1,38) = 31.92, P < 0.005) during MI. The process of MI effectively facilitated MEP amplitude in controls but not in ET patients, regardless of side of stimulation or motor tasks. We provide evidence to demonstrate impairment of MI in a group of ET patients compared with healthy controls. The basis for this novel finding is unclear, and further studies are warranted to determine whether it is related to cerebellar or motor cortical dysfunction. © 2007 Movement Disorder Society [source]

Motor imagery after stroke: Relating outcome to motor network connectivity,

ANNALS OF NEUROLOGY, Issue 5 2009
Nikhil Sharma PhD
Objective Neuroplasticity is essential for recovery after stroke and is the target for new stroke therapies. During recovery from subcortical motor stroke, brain activations associated with movement may appear normal despite residual functional impairment. This raises an important question: how far does recovery of motor performance depend on the processes that precede movement execution involving the premotor and prefrontal cortex, rather than recovery of the corticospinal system alone? Methods We examined stroke patients with functional magnetic resonance imaging while they either imagined or executed a finger-thumb opposition sequence. In addition to classical analyses of regional activations, we studied neuroplasticity in terms of differential network connectivity using structural equation modeling. The study included 8 right-handed patients who had suffered a left-hemisphere subcortical ischemic stroke with paresis, and 13 age-matched healthy controls. Results With good functional recovery, the regional activations had returned to normal in patients. However, connectivity within the extended motor network remained abnormal. These abnormalities were seen predominantly during motor imagery and correlated with motor performance. Interpretation Our results indicate that neuroplasticity can manifest itself as differences in connectivity among cortical areas remote from the infarct, rather than in the degree of regional activation. Connection strengths between nodes of the cortical motor network correlate with motor outcome. The altered organization of connectivity of the prefrontal areas may reflect the role of the prefrontal cortex in higher order planning of movement. Our results are relevant to the assessment and understanding of emerging physical and neurophysiological therapies for stroke rehabilitation. Ann Neurol 2009;66:604,616 [source]

Effector-independent representations of simple and complex imagined finger movements: a combined fMRI and TMS study

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2003
J. P. Kuhtz-Buschbeck
Abstract Kinesthetic motor imagery and actual execution of movements share a common neural circuitry. Functional magnetic resonance imaging was used in 12 right-handed volunteers to study brain activity during motor imagery and execution of simple and complex unimanual finger movements of the dominant and the nondominant hand. In the simple task, a flexible object was rhythmically compressed between thumb, index and middle finger. The complex task was a sequential finger-to-thumb opposition movement. Premotor, posterior parietal and cerebellar regions were significantly more active during motor imagery of complex movements than during mental rehearsal of the simple task. In 10 of the subjects, we also used transcranial magnetic brain stimulation to examine corticospinal excitability during the same motor imagery tasks. Motor-evoked potentials increased significantly over values obtained in a reference condition (visual imagery) during imagery of the complex, but not of the simple movement. Imagery of finger movements of either hand activated left dorsal and ventral premotor areas and the supplementary motor cortex regardless of task complexity. The effector-independent activation of left premotor areas was particularly evident in the simple motor imagery task and suggests a left hemispherical dominance for kinesthetic movement representations in right-handed subjects. [source]

xBCI: A Generic Platform for Development of an Online BCI System

IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 4 2010
I Putu Susila Non-member
Abstract A generic platform for realizing an online brain,computer interface (BCI) named xBCI was developed. The platform consists of several functional modules (components), such as data acquisition, storage, mathematical operations, signal processing, network communication, data visualization, experiment control, and real-time feedback presentation. Users can easily build their own BCI systems by combining the components on a graphical-user-interface (GUI) based diagram editor. They can also extend the platform by adding components as plug-ins or by creating components using a scripting language. The platform works on multiple operating systems and supports parallel (multi-threaded) data processing and data transfer to other PCs through a network transmission control protocol/internet protocol or user datagram protocol (TCP/IP or UDP). A BCI system based on motor imagery and a steady-state visual evoked potential (SSVEP) based BCI system were constructed and tested on the platform. The results show that the platform is able to process multichannel brain signals in real time. The platform provides users with an easy-to-use system development tool and reduces the time needed to develop a BCI system. Copyright © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source]

Dynamic spatial cognition: Components, functions, and modifiability of body schema1

JAPANESE PSYCHOLOGICAL RESEARCH, Issue 3 2006
KAORU SEKIYAMA
Abstract:, There has been substantial progress towards the understanding of the classical notion of "body schema," with recent advances in experimental methodology and techniques. Mental rotation of the hands can be used as a tool to investigate body schema. Research has shown that implicit motor imagery (i.e., mental simulated movements) can be generated based on the body schema, by combining both stored and incoming sensory information. Multimodal stimulation of peripersonal space has also served as an experimental paradigm for the study of body schema. Perception of peripersonal space is based on body-part-centered space coding that is considered as a manifestation of the body schema, its function being to integrate visual, tactile, and proprioceptive information, and perhaps motor plans as well. By combining such experimental paradigms with neuroimaging and neurophysiological techniques, research has converged to show that the parietal association cortex and premotor cortex are important for the body schema. Multimodal perception of body parts and peripersonal space have been also studied in relation to prism adaptation and tool use effects, indicating a clear modifiability of the body schema. Following prolonged adaptation to reversed vision, a reversed hand representation can be added to the body schema like a tool. The stored component of the body schema may not be established well in young children. But once established it may not be deleted even after an arm is amputated, although it may be weakened. All of these findings help to specify properties of the body schema, its components, functions, and modifiabilities. [source]