Sensorimotor Modulation Research Articles

Sensorimotor Modulation Assessment and Brain-Computer Interface Training in Disorders of Consciousness

ObjectivesTo assess awareness in subjects who are in a minimally conscious state by using an electroencephalogram-based brain-computer interface (BCI), and to determine whether these patients may learn to modulate sensorimotor rhythms with visual feedback, stereo auditory feedback, or both. DesignInitial assessment included imagined hand movement or toe wiggling to activate sensorimotor areas and modulate brain rhythms in 90 trials (4 subjects). Within-subject and within-group analyses were performed to evaluate significant activations. A within-subject analysis was performed involving multiple BCI technology training sessions to improve the capacity of the user to modulate sensorimotor rhythms through visual and auditory feedback. SettingHospital, homes of subjects, and a primary care facility. ParticipantsSubjects (N=4; 3 men, 1 woman) who were in a minimally conscious state (age range, 27–53y; 1–12y after brain injury). InterventionsNot applicable. Main Outcome MeasuresAwareness detection was determined from sensorimotor patterns that differed for each motor imagery task. BCI performance was determined from the mean classification accuracy of brain patterns by using a BCI signal processing framework and assessment of performance in multiple sessions. ResultsAll subjects demonstrated significant and appropriate brain activation during the initial assessment, and real-time feedback was provided to improve arousal. Consistent activation was observed in multiple sessions. ConclusionsThe electroencephalogram-based assessment showed that patients in a minimally conscious state may have the capacity to operate a simple BCI-based communication system, even without any detectable volitional control of movement.

Sensorimotor modulation differs with load type during constant finger force or position.

During submaximal isometric contraction, there are two different load types: production of a constant force against a rigid restraint (force task), and maintenance of position against a constant load (position task). Previous studies reported that the time to task failure during a fatigue task was twice as long in the force task compared with the position task. Sensory feedback processing may contribute to these differences. The purpose of the current study was to determine the influence of load types during static muscle contraction tasks on the gating effect, i.e., attenuation of somatosensory-evoked potentials (SEPs) and the cortical silent period (cSP). Ten healthy subjects contracted their right first dorsal interosseus muscle by abducting their index finger for 90 s, to produce a constant force against a rigid restraint that was 20% of the maximum voluntary contraction (force task), or to maintain a constant position with 10° abduction of the metacarpophalangeal joint against the same load (position task). Somatosensory evoked potentials (SEPs) were recorded from C3′ by stimulating either the right ulnar or median nerve at the wrist while maintaining contraction. The cortical silent period (cSP) was also elicited by transcranial magnetic stimulation. Reduction of the amplitude of the P45 component of SEPs was significantly larger during the position task than during the force task and under control rest conditions when the ulnar nerve, but not the median nerve, was stimulated. The position task had a significantly shorter cSP duration than the force task. These results suggest the need for more proprioceptive information during the position task than the force task. The shorter duration of the cSP during the position task may be attributable to larger amplitude of heteronymous short latency reflexes. Sensorimotor modulations may differ with load type during constant finger force or position tasks.

Brain spontaneous fluctuations in sensorimotor regions were directly related to eyes open and eyes closed: evidences from a machine learning approach.

Previous studies have demonstrated that the difference between resting-state brain activations depends on whether the subject was eyes open (EO) or eyes closed (EC). However, whether the spontaneous fluctuations are directly related to these two different resting states are still largely unclear. In the present study, we acquired resting-state functional magnetic resonance imaging data from 24 healthy subjects (11 males, 20.17 ± 2.74 years) under the EO and EC states. The amplitude of the spontaneous brain activity in low-frequency band was subsequently investigated by using the metric of fractional amplitude of low frequency fluctuation (fALFF) for each subject under each state. A support vector machine (SVM) analysis was then applied to evaluate whether the category of resting states could be determined from the brain spontaneous fluctuations. We demonstrated that these two resting states could be decoded from the identified pattern of brain spontaneous fluctuations, predominantly based on fALFF in the sensorimotor module. Specifically, we observed prominent relationships between increased fALFF for EC and decreased fALFF for EO in sensorimotor regions. Overall, the present results indicate that a SVM performs well in the discrimination between the brain spontaneous fluctuations of distinct resting states and provide new insight into the neural substrate of the resting states during EC and EO.

Altered resting state brain networks in Parkinson's disease.

Parkinson’s disease (PD) is a neurodegenerative disorder affecting dopaminergic neurons in the substantia nigra leading to dysfunctional cortico-striato-thalamic-cortical loops. In addition to the characteristic motor symptoms, PD patients often show cognitive impairments, affective changes and other non-motor symptoms, suggesting system-wide effects on brain function. Here, we used functional magnetic resonance imaging and graph-theory based analysis methods to investigate altered whole-brain intrinsic functional connectivity in PD patients (n = 37) compared to healthy controls (n = 20). Global network properties indicated less efficient processing in PD. Analysis of brain network modules pointed to increased connectivity within the sensorimotor network, but decreased interaction of the visual network with other brain modules. We found lower connectivity mainly between the cuneus and the ventral caudate, medial orbitofrontal cortex and the temporal lobe. To identify regions of altered connectivity, we mapped the degree of intrinsic functional connectivity both on ROI- and on voxel-level across the brain. Compared to healthy controls, PD patients showed lower connectedness in the medial and middle orbitofrontal cortex. The degree of connectivity was also decreased in the occipital lobe (cuneus and calcarine), but increased in the superior parietal cortex, posterior cingulate gyrus, supramarginal gyrus and supplementary motor area. Our results on global network and module properties indicated that PD manifests as a disconnection syndrome. This was most apparent in the visual network module. The higher connectedness within the sensorimotor module in PD patients may be related to compensation mechanism in order to overcome the functional deficit of the striato-cortical motor loops or to loss of mutual inhibition between brain networks. Abnormal connectivity in the visual network may be related to adaptation and compensation processes as a consequence of altered motor function. Our analysis approach proved sensitive for detecting disease-related localized effects as well as changes in network functions on intermediate and global scale.

Semantic embodiment, disembodiment or misembodiment? In search of meaning in modules and neuron circuits

“Embodied” proposals claim that the meaning of at least some words, concepts and constructions is grounded in knowledge about actions and objects. An alternative “disembodied” position locates semantics in a symbolic system functionally detached from sensorimotor modules. This latter view is not tenable theoretically and has been empirically falsified by neuroscience research. A minimally-embodied approach now claims that action–perception systems may “color”, but not represent, meaning; however, such minimal embodiment (misembodiment?) still fails to explain why action and perception systems exert causal effects on the processing of symbols from specific semantic classes. Action perception theory (APT) offers neurobiological mechanisms for “embodied” referential, affective and action semantics along with “disembodied” mechanisms of semantic abstraction, generalization and symbol combination, which draw upon multimodal brain systems. In this sense, APT suggests integrative-neuromechanistic explanations of why both sensorimotor and multimodal areas of the human brain differentially contribute to specific facets of meaning and concepts.

Sensorimotor Modulation of Mood and Depression: In Search of an Optimal Mode of Stimulation

Depression involves a dysfunction in an affective fronto-limbic circuitry including the prefrontal cortices, several limbic structures including the cingulate cortex, the amygdala, and the hippocampus as well as the basal ganglia. A major emphasis of research on the etiology and treatment of mood disorders has been to assess the impact of centrally generated (top-down) processes impacting the affective fronto-limbic circuitry. The present review shows that peripheral (bottom-up) unipolar stimulation via the visual and the auditory modalities as well as by physical exercise modulates mood and depressive symptoms in humans and animals and activates the same central affective neurocircuitry involved in depression. It is proposed that the amygdala serves as a gateway by articulating the mood regulatory sensorimotor stimulation with the central affective circuitry by emotionally labeling and mediating the storage of such emotional events in long-term memory. Since both amelioration and aggravation of mood is shown to be possible by unipolar stimulation, the review suggests that a psychophysical assessment of mood modulation by multimodal stimulation may uncover mood ameliorative synergisms and serve as adjunctive treatment for depression. Thus, the integrative review not only emphasizes the relevance of investigating the optimal levels of mood regulatory sensorimotor stimulation, but also provides a conceptual springboard for related future research.

Reduced Cerebral Perfusion of Putamen and Insular Cortex in Patients with Idiopathic Restless Leg Syndrome

Address for correspondence Seung Bong Hong, MD, PhD Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Irwon-dong, Gangnam-gu, Seoul 135-710, Korea Tel: +82-2-3410-3592 Fax: +82-2-3410-0052 E-mail: sbhong@skku.edu Objectives: To evaluate the cerebral perfusion pattern of idiopathic restless leg syndrome (RLS). Methods: We performed Tc-ethyl cysteinate dimer brain single-photon emission computed tomography (SPECT) in 36 drug-naive patients with RLS patients and 30 age-and gender matched normal cotrols during wakefulness. Their SPECT images underwent statistical parametric mapping analysis. Results: Mean age of patients and normal controls was 48.3 years and 80% of them were women. Most patients reported the sleep onset and maintenance insomnia due to RLS symtoms. Average duration of RLS was 10.5 years. Mean score of international RLS was 26.6, suggesting moderate to severe severity. They did not report daytime sleepiness (mean Epworth sleepiness scale, 7.0). All subjects underwent polysomnography, showing no definite obstructive sleep apnea syndrome. Seventeen of them (56.6%) had periodic leg movement during sleep (PLMS). Sleep quality was more deteriorated in patients than that in normal controls (increased sleep latency and arousal index, which resulted in reduced sleep efficiency). In RLS pateints, cerebral blood flow was decreased in the right putamen and insular cortex compared to normal controls (uncorrected p<0.005). There was no brain region showing increased cerebral perfusion in patients. Regional cerebral perfusion was not correlated to any sleep parameter including PLMS index or movement arousal index. Conclusions: Reduced cerebral perfusion in putamen and insular cortex in RLS suggested functional abnormalities in motor circuit and sensori-motor modulation, which may be related to pathophysiology of idiopathic RLS. J Korean Sleep Res Soc 2012;9:10-14

The visual control of landing and obstacle avoidance in the fruit flyDrosophila melanogaster

Landing behavior is one of the most critical, yet least studied, aspects of insect flight. In order to land safely, an insect must recognize a visual feature, navigate towards it, decelerate, and extend its legs in preparation for touchdown. Although previous studies have focused on the visual stimuli that trigger these different components, the complete sequence has not been systematically studied in a free-flying animal. Using a real-time 3D tracking system in conjunction with high speed digital imaging, we were able to capture the landing sequences of fruit flies (Drosophila melanogaster) from the moment they first steered toward a visual target, to the point of touchdown. This analysis was made possible by a custom-built feedback system that actively maintained the fly in the focus of the high speed camera. The results suggest that landing is composed of three distinct behavioral modules. First, a fly actively turns towards a stationary target via a directed body saccade. Next, it begins to decelerate at a point determined by both the size of the visual target and its rate of expansion on the retina. Finally, the fly extends its legs when the visual target reaches a threshold retinal size of approximately 60 deg. Our data also let us compare landing sequences with flight trajectories that, although initially directed toward a visual target, did not result in landing. In these 'fly-by' trajectories, flies steer toward the target but then exhibit a targeted aversive saccade when the target subtends a retinal size of approximately 33 deg. Collectively, the results provide insight into the organization of sensorimotor modules that underlie the landing and search behaviors of insects.

Sensorimotor Modulation of the Human Brain-Gut Axis Induced by Non-Invasive Lumbosacral Magnetic Stimulation

Sensorimotor Modulation of the Human Brain-Gut Axis Induced by Non-Invasive Lumbosacral Magnetic Stimulation

Credit Assignment in Multiple Goal Embodied Visuomotor Behavior

The intrinsic complexity of the brain can lead one to set aside issues related to its relationships with the body, but the field of embodied cognition emphasizes that understanding brain function at the system level requires one to address the role of the brain-body interface. It has only recently been appreciated that this interface performs huge amounts of computation that does not have to be repeated by the brain, and thus affords the brain great simplifications in its representations. In effect the brain's abstract states can refer to coded representations of the world created by the body. But even if the brain can communicate with the world through abstractions, the severe speed limitations in its neural circuitry mean that vast amounts of indexing must be performed during development so that appropriate behavioral responses can be rapidly accessed. One way this could happen would be if the brain used a decomposition whereby behavioral primitives could be quickly accessed and combined. This realization motivates our study of independent sensorimotor task solvers, which we call modules, in directing behavior. The issue we focus on herein is how an embodied agent can learn to calibrate such individual visuomotor modules while pursuing multiple goals. The biologically plausible standard for module programming is that of reinforcement given during exploration of the environment. However this formulation contains a substantial issue when sensorimotor modules are used in combination: The credit for their overall performance must be divided amongst them. We show that this problem can be solved and that diverse task combinations are beneficial in learning and not a complication, as usually assumed. Our simulations show that fast algorithms are available that allot credit correctly and are insensitive to measurement noise.

The sensory and motor representation of synchronized oscillations in the globus pallidus in patients with primary dystonia

In 15 patients with primary dystonia (six cervical and nine generalized dystonias) who were treated with bilateral chronic pallidal stimulation, we investigated the sensorimotor modulation of the oscillatory local field potentials (LFPs) recorded from the pallidal electrodes. We correlated these with the surface electromyograms in the affected muscles. The effects of involuntary, passive and voluntary movement and muscle-tendon vibration on frequency ranges of 0-3 Hz, theta (3-8 Hz), alpha (8-12 Hz), low (12-20 Hz) and high beta (20-30 Hz), and low (30-60 Hz) and high gamma (60-90 Hz) power were recorded and compared between cervical and generalized dystonia groups. Significant decreases in LFP synchronization at 8-20 Hz occurred during the sensory modulation produced by voluntary or passive movement or vibration. Voluntary movement also caused increased gamma band activity (30-90 Hz). Dystonic involuntary muscle spasms were specifically associated with increased theta, alpha and low beta (3-18 Hz). Furthermore, the increase in the frequency range of 3-20 Hz correlated with the strength of the muscle spasms and preceded them by approximately 320 ms. Differences in modulation of pallidal oscillation between cervical and generalized dystonias were also revealed. This study yields new insights into the pathophysiological mechanisms of primary dystonias and their treatment using pallidal deep brain stimulation.

Simulating a shaping task.

A neural network simulation of Eckerman, Hienz, Stern, & Kowlowitz' (1980) experiment showed a good match to the effective shaping of the location of a pigeon's keypeck. The neural network model was biologically based on In-Vitro Reinforcement (IVR) principles of learning. The behavioral function of the model was a Win-Stay strategy. Results indicated that control by consequences can account for a substantial proportion of the shaping reported in the original experiment. The simulation and its analysis are good examples of new techniques for neural network simulation, including semi-situational simulations and direct analysis. ********** Shaping is one of the most widely used techniques in applied behavior analysis. Despite this, very little experimental analysis of shaping has been reported from the laboratory. The present study continues the authors' efforts to use neural network simulations as a tool for the analysis of shaping. Specifically, we will show how a network based on the principles of In-Vitro Reinforcement (IVR--Stein, 1997; Stein, Xue, & Belluzzi, 1993; 1994; Stein & Belluzzi, 1989) accounts for experimental results of pigeons' key pecks shaped using a Long Key apparatus (Eckerman, Hienz, Stem, & Kowlowitz, 1980). Across psychology, the use of computer simulations is becoming more and more common. Most of these simulations are not behavioral. And most of the methods and techniques developed to analyze these simulations are not appropriate to a behavioral analysis. Even in the case of behavioral simulations, it is not always the case that the phenomena simulated are of especial interest to the clinician. The present study uses a novel technique called direct analysis (Kemp & Eckerman, 2001), which allows the prediction of behavior from almost any experimental analysis. By selecting an experimental analysis of shaping, we hope that the present report illustrates how simulating a neural network on a computer can lead to analyses of behavior of value to the clinician. Direct analysis means subscribing to the desiderata proposed by Church (1997). One way of speaking about direct analysis is to say it involves attempting to simulate an experiment, rather than an experimental effect. This means that the computer software that performs the simulation is composed of at least three separate programs (called modules), one modeling the experimental procedure and apparatus, another modeling the organism's sensorimotor systems, and the third modeling the behavior. The outputs of one module are input into the next, in a cycle. Kemp & Eckerman (2001) refer to this sort of simulation as situational. The third component module is the neural network model. The remainder of the software constitutes what Kemp & Eckerman call the In Situ testbed, used to evaluate the performance of the model with respect to the performance of the original organisms in the same experimental procedure. Because the output of the behavioral module impacts the sensorimotor module, the level of detail at which the behavior is modeled must be very fine grained--both temporally and spatially. Not only each session, but each trial and each response, and often unmeasured responses (such as crossover responses and observing responses, etc.) as well, must be simulated individually. This is what we mean by simulating an experiment, rather than just an experimental effect. Direct analysis is distinct from other types of quantitative analysis of behavior. Typical computer simulations merely calculate the functional relations. The inputs to traditional simulations are parameters describing the contingencies and the outputs are parameters characterizing the behavior. As such, they are abstractions away from the moment-to-moment details of an organism interacting with its environment (Skinner, 1976). In contrast, the output from a situational simulation system is a record of behavior with the same structure as the data recorded from the original experiment. …

Feeding behavior of 6- to 12-month-old infants: Assessment and sources of parental information

Both the infant's development of feeding skill and self-regulatory competence during the second 6 months of life have implications for weaning and for a weaning diet. This article examines four categories of feeding skills: taking food from a spoon; handling thicker, lumpy foods and foods that require chewing; self-feeding with fingers or a spoon; and drinking from a cup and managing the bottle. These skills are fundamental for the development of self-regulatory competence through the phases of sensorimotor modulation (from 3 months of age to approximately 9 to 12 months) and control (9 to 12 months of age). Available instruments to assess feeding skill and self-regulatory competence are described. Questions concerning feeding practices in relation to the infant's development of feeding skill and self-regulatory competence are raised. Potential conflicts between professional and lay sources, informational methods used and preferred, and the types of problems for which help is sought are discussed.

Animal Behavior and Internal Drives

Animal Behavior and Internal Drives