Effect of Robotic Exoskeleton Motion Constraints on Upper Limb Muscle Synergies: A Case Study.

Evidence exists that changes in composition, timing, and number of muscle synergies can be correlated to functional changes resulting from neurological injury. These changes can also serve as an indicator of level of motor impairment. As such, synergy analysis can be used as an assessment tool for robotic rehabilitation.

Examining Social Cognition with Embodied Robots: Does Prior Experience with a Robot Impact Feedback-associated Learning in a Gambling Task?

Social agents rely on the ability to use feedback to learn and modify their behavior. The extent to which this happens in social contexts depends on motivational, cognitive and/or affective parameters. For instance, feedback-associated learning occurs at different rates when the outcome of an action (e.

The SE-AssessWrist for robot-aided assessment of wrist stiffness and range of motion: Development and experimental validation.

Introduction: Physical human-robot interaction offers a compelling platform for assessing recovery from neurological injury; however, robots currently used for assessment have typically been designed for the requirements of rehabilitation, not assessment. In this work, we present the design, control, and experimental validation of the SE-AssessWrist, which extends the capabilities of prior robotic devices to include complete wrist range of motion assessment in addition to stiffness evaluation.

Methods: The SE-AssessWrist uses a Bowden cable-based transmission in conjunction with series elastic actuation to increase device range of motion while not sacrificing torque output.

A win-win situation: Does familiarity with a social robot modulate feedback monitoring and learning?

Social species rely on the ability to modulate feedback-monitoring in social contexts to adjust one's actions and obtain desired outcomes. When being awarded positive outcomes during a gambling task, feedback-monitoring is attenuated when strangers are rewarded, as less value is assigned to the awarded outcome. This difference in feedback-monitoring can be indexed by an event-related potential (ERP) component known as the Reward Positivity (RewP), whose amplitude is enhanced when receiving positive feedback.

Subthreshold error corrections predict adaptive post-error compensations.

Relatively little is known about the relation between subthreshold error corrections and post-error behavioral compensations. The present study utilized lateralized beta power, which has been shown to index response preparation, to examine subthreshold error corrections in a task known to produce response conflict, the Simon task. We found that even when an overt correction is not made, greater activation of the corrective response, indexed by beta suppression ipsilateral to the initial responding hand, predicted post-error speeding, and enhanced post-error accuracy at the single-trial level.

Contrasting time and frequency domains: ERN and induced theta oscillations differentially predict post-error behavior.

The present study investigated the neural dynamics of error processing in both the time and frequency domains, as well as associated behavioral phenomena, at the single-trial level. We used a technique that enabled us to separately investigate the evoked and induced aspects of the EEG signal (Cohen & Donner, 2013, Journal of Neurophysiology, 110[12], 2752-2763). We found that at the single-trial level, while the (evoked) error-related negativity (ERN) predicted only post-error slowing (PES)-and only when errors occurred on incongruent trials-induced frontal midline theta power served as a robust predictor of both PES and post-error accuracy (PEA) regardless of stimulus congruency.

A Myoelectric Control Interface for Upper-Limb Robotic Rehabilitation Following Spinal Cord Injury.

Spinal cord injury (SCI) is a widespread, life-altering injury leading to impairment of sensorimotor function that, while once thought to be permanent, is now being treated with the hope of one day being able to restore function. Surface electromyography (EMG) presents an opportunity to examine and promote human engagement at the neuromuscular level, enabling new protocols for intervention that could be combined with robotic rehabilitation, particularly when robot motion or force sensing may be unusable due to the user's impairment. In this paper, a myoelectric control interface to an exoskeleton for the elbow and wrist was evaluated on a population of ten able-bodied participants and four individuals with cervical-level SCI.

Ready, set, explore! Event-related potentials reveal the time-course of exploratory decisions.

The decision trade-off between exploiting the known and exploring the unknown has been studied using a variety of approaches and techniques. Surprisingly, electroencephalography (EEG) has been underused in this area of study, even though its high temporal resolution has the potential to reveal the time-course of exploratory decisions. We addressed this issue by recording EEG data while participants tried to win as many points as possible in a two-choice gambling task called a two-armed bandit.

Dissociating the effect of flavor and nicotine in smokeless tobacco products using electroencephalography: The case of wintergreen flavors.

The increased consumption of tobacco products in recent years has been linked, among other factors, to the presence of added flavors. Although flavors are important in explaining consumption, their effects in the brain have until now been unexplored. In the present study, we investigated how electrophysiology can serve to dissociate the effects of nicotine and flavor.

Learning From the Slips of Others: Neural Correlates of Trust in Automated Agents.

With the rise of increasingly complex artificial intelligence (AI), there is a need to design new methods to monitor AI in a transparent, human-aware manner. Decades of research have demonstrated that people, who are not aware of the exact performance levels of automated algorithms, often experience a mismatch in expectations. Consequently, they will often provide either too little or too much trust in an algorithm.

Speeded response errors and the error-related negativity modulate early sensory processing.

Empirical research demonstrates that when the time following error commission is constrained, subsequent sensory processing can be impaired (Buzzell et al., 2017). This reduction in sensory processing is presumably due to a bottleneck for cognitive resources produced by an overlap between error processing and subsequent stimulus processing.

Characterization of surface electromyography patterns of healthy and incomplete spinal cord injury subjects interacting with an upper-extremity exoskeleton.

Rehabilitation exoskeletons may make use of myoelectric control to restore in patients with significant motor impairment following a spinal cord injury (SCI) a sense of volitional control over their limb - a crucial component for recovery of movement. Little investigation has been done into the feasibility of using surface electromyography (sEMG) as an exoskeleton control interface for SCI patients, whose impairment manifests in a highly variable way across the patient population. We have demonstrated that by using only a small subset of features extracted from eight bipolar electrodes recording on the upper arm and forearm muscles, we can achieve high predictive accuracy for the intended direction of motion.

Nicotine-induced and D1-receptor-dependent dendritic remodeling in a subset of dorsolateral striatum medium spiny neurons.

Nicotine is one of the most addictive substances known, targeting multiple memory systems, including the ventral and dorsal striatum. One form of neuroplasticity commonly associated with nicotine is dendrite remodeling. Nicotine-induced dendritic remodeling of ventral striatal medium spiny neurons (MSNs) is well-documented.

Error-Induced Blindness: Error Detection Leads to Impaired Sensory Processing and Lower Accuracy at Short Response-Stimulus Intervals.

Empirical evidence indicates that detecting one's own mistakes can serve as a signal to improve task performance. However, little work has focused on how task constraints, such as the response-stimulus interval (RSI), influence post-error adjustments. In the present study, event-related potential (ERP) and behavioral measures were used to investigate the time course of error-related processing while humans performed a difficult visual discrimination task.

Neural activity reveals perceptual grouping in working memory.

There is extensive evidence that the contralateral delay activity (CDA), a scalp recorded event-related brain potential, provides a reliable index of the number of objects held in visual working memory. Here we present evidence that the CDA not only indexes visual object working memory, but also the number of locations held in spatial working memory. In addition, we demonstrate that the CDA can be predictably modulated by the type of encoding strategy employed.

Using Electrophysiological Measures to Assess the Consumer Acceptability of Smokeless Tobacco Products.

Introduction: Adequate evaluation of novel tobacco products must include investigation of consumers' psychological response to such products. Traditionally, subjective scales of product liking have been used to assess consumer acceptability of tobacco products. However, subjective scales may miss cognitive changes that can only be captured by direct neurophysiological assessment.

Uncertainty-dependent activity within the ventral striatum predicts task-related changes in response strategy.

Recent neuroimaging work has demonstrated that the ventral striatum (VS) encodes confidence in perceptual decisions. However, it remains unclear whether perceptual uncertainty can signal the need to adapt behavior (such as by responding more cautiously) and whether such behavioral changes are related to uncertainty-dependent activity within the VS. Changes in response strategy have previously been observed following errors and are associated with both medial frontal cortex (MFC) and VS, two components of the performance-monitoring network.

Adolescent nicotine induces persisting changes in development of neural connectivity.

Adolescent nicotine induces persisting changes in development of neural connectivity. A large number of brain changes occur during adolescence as the CNS matures. These changes suggest that the adolescent brain may still be susceptible to developmental alterations by substances which impact its growth.

Role of the D3 dopamine receptor in nicotine sensitization.

Adolescent cigarette use is associated with reduced quitting success and continued smoking in adulthood. Interestingly, polymorphisms of the dopamine D3 receptor (DRD3) gene have been associated with smoking behavior, and the receptor is expressed in an age- and brain region-dependent manner that suggests relevance to addiction. Here, we investigate the possible role of dopamine-related receptors, including DRD3 and an intriguing splice variant known as D3nf, in nicotine-induced sensitization.

The efficacy of auditory probes in indexing cognitive workload is dependent on stimulus complexity.

We examined whether the utility of a recently developed auditory probe technique for indexing cognitive workload was dependent on the stimulus properties of the probes. EEG was recorded while participants played a videogame under various levels of cognitive workload. At each level of workload, participants were probed with one of four different types of auditory stimuli: novel complex, repeated complex, novel simple, or repeated simple sounds.

Psychophysiological support of increasing attentional reserve during the development of a motor skill.

The aim of this study was to determine the relationship between motor skill and attentional reserve. Participants practiced a reaching task with the dominant upper extremity, to which a distortion of the visual feedback was applied, while a control group performed the same task without distortion. Event-related brain potentials (ERPs), elicited by auditory stimuli were recorded throughout practice.

Anxiety status affects nicotine- and baclofen-induced locomotor activity, anxiety, and single-trial conditioned place preference in male adolescent rats.

Adolescents have an increased vulnerability to nicotine and anxiety may play a role in the development of nicotine abuse. One possible treatment for anxiety disorders and substance abuse is the GABAB agonist, baclofen. The aim of the present study was to determine the effect of anxiety-like behavior on single-trial nicotine conditioned place preference in adolescent rats, and to assess the action of baclofen.

The N2 ERP component as an index of impaired cognitive control in smokers.

Impaired cognitive control has been proposed as a hallmark of nicotine dependence and is thought to arise, in part, from synaptic alterations in anterior cingulate cortex (ACC), a primary component of the dopamine reward pathway. The N2 component of the event-related potential (ERP) appears to index a cognitive control process in paradigms such as the visual go/no-go task. Moreover, as dipole-modeling has suggested that the neural generator of the N2 component can be localized to the ACC, this component may prove useful for investigating impairments of cognitive control in smokers.

Prestimulus oscillations in the alpha band of the EEG are modulated by the difficulty of feature discrimination and predict activation of a sensory discrimination process.

Recent work has demonstrated that the occipital-temporal N1 component of the ERP is sensitive to the difficulty of visual discrimination, in a manner that cannot be explained by simple differences in low-level visual features, arousal, or time on task. These observations provide evidence that the occipital-temporal N1 component is modulated by the application of top-down control. However, the timing of this control process remains unclear.