Frontal-to-visual information flow explains predictive motion tracking.

Predictive tracking demonstrates our ability to maintain a line of vision on moving objects even when they temporarily disappear. Models of smooth pursuit eye movements posit that our brain achieves this ability by directly streamlining motor programming from continuously updated sensory motion information. To test this hypothesis, we obtained sensory motion representation from multivariate electroencephalogram activity while human participants covertly tracked a temporarily occluded moving stimulus with their eyes remaining stationary at the fixation point. The sensory motion representation of the occluded target evolves to its maximum strength at the expected timing of reappearance, suggesting a timely modulation of the internal model of the visual target. We further characterize the spatiotemporal dynamics of the task-relevant motion information by computing the phase gradients of slow oscillations. We discovered a predominant posterior-to-anterior phase gradient immediately after stimulus occlusion; however, at the expected timing of reappearance, the axis reverses the gradient, becoming anterior-to-posterior. The behavioral bias of smooth pursuit eye movements, which is a signature of the predictive process of the pursuit, was correlated with the posterior division of the gradient. These results suggest that the sensory motion area modulated by the prediction signal is involved in updating motor programming.

Cadaveric Study of Thread Carpal Tunnel Release Using Newly Developed Thread, With a Histologic Perspective.

OBJECTIVE: To examine the usefulness and feasibility of modified thread carpal tunnel release (TCTR) by comparing the results of using pre-existing commercial thread with those of a newly developed thread (Smartwire-01). METHODS: A total of 17 cadaveric wrists were used in the study. The modified TCTR method was practiced by two different experts. Pre-existing commercial surgical dissecting thread (Loop&ShearTM) was used for five wrists and the newly developed Smartwire-01 was used for twelve wrists. The gross and microanatomy of the specimens were evaluated by a blinded anatomist. RESULTS: Both types of thread were able to cut the TCL similarly. Gross anatomy and histologic findings showed that there was no significant difference between the two types of threads. However, the practitioners felt that it was easier to cut the TCL using the newly-developed thread. CONCLUSION: TCTR using Smartwire-01 was as effective as pre-existing Loop&ShearTM, with better user experiences.

Volumetric Variability of the Ventromedial Prefrontal Cortex Reflects the Propensity for Engaging in High-Stakes Gambling Behavior.

The human ventromedial prefrontal cortex (vmPFC) has been traditionally associated with decision-making under risk. Neuroimaging studies of such decision-making processes have largely focused on patients with vmPFC lesions or pathological gambling behavior, leading to a relative paucity of work focusing on the structural variability of the vmPFC in healthy individuals. To address this, we developed a decision-making task that allowed healthy players to choose to participate in either low stakes or high-stakes gambling on a trial-by-trial basis, and computed a metric that indexes the propensity for engaging in gambles with greater potential payoffs. We leveraged voxel-based morphometric analyses to examine the association between prefrontal gray matter volume and individual differences in the propensity for seeking high-risk/high-reward situations. Our analyses showed that vmPFC gray matter volume was inversely correlated with an increased tendency for engaging in high-stakes gambling. These results converge with findings from functional neuroimaging and brain lesion studies of vmPFC, and further extend them to show that normative variability in brain structure could also underpin risk-taking behavior.

A Cadaveric Study of Thread Cubital Tunnel Release with Newly Developed Threads.

OBJECTIVE: The percutaneous thread transection technique is a surgical dissecting method using a dissecting thread inserted through a needle under ultrasound guidance without skin incision. As the new dissecting threads were developed domestically, this cadaver study was conducted to compare the effectiveness and safety between the new threads (ultra V sswire and smartwire-01) and a pre-existing commercial dissecting thread (loop & shear) by demonstrating a modified looped thread cubital tunnel release. METHODS: The percutaneous cubital tunnel release procedure was performed on 29 fresh cadaveric upper extremities. The preexisting commercial thread was used in 5 upper extremities. The two newly developed threads were used in 24 upper extremities. Two practitioners performed the procedures separately. After the modified looped thread cubital release, anatomical and histological analyses were performed by a blinded anatomist. The presence of the dissected cubital tunnel and damaged adjacent soft tissue was assessed. RESULTS: Out of the 29 cadaveric upper extremities, 27 specimens showed complete dissection of the Osborne ligament and the proximal fascia of the flexor carpi ulnaris muscle. One specimen was incompletely dissected in each of the ultra V sswire and smartwire-01 groups. There were no injuries of adjacent structures including the ulnar nerve, ulnar artery, medial antebrachial cutaneous nerve, or flexor tendon with either the commercial thread or the newly developed threads. The anatomical analysis revealed clear and sharp incisional margins of the cubital tunnel in the Smartwire-01 and loop & shear groups. All three kinds of threads maintained proper linear elasticity for easy handling during the procedure. The smartwire-01 provided higher visibility in ultrasound than the other threads. CONCLUSION: The newly developed threads were effective and safe for use in the thread cubital tunnel release procedure.

Does periosteum promote chondrogenesis? A comparison of free periosteal and perichondrial grafts in the regeneration of ear cartilage.

BACKGROUND: Elastic ear cartilage is a good source of tissue for support or augmentation in plastic and reconstructive surgery. However, the amount of ear cartilage is limited and excessive use of cartilage can cause deformation of the auricular framework. This animal study investigated the potential of periosteal chondrogenesis in an ear cartilage defect model. METHODS: Twelve New Zealand white rabbits were used in the present study. Four ear cartilage defects were created in both ears of each rabbit, between the central artery and marginal veins. The defects were covered with perichondrium (group 1), periosteum taken from the calvarium (group 2), or periosteum taken from the tibia (group 3). No coverage was performed in a control group (group 4). All animals were sacrificed 6 weeks later, and the ratio of neo-cartilage to defect size was measured. RESULTS: Significant chondrogenesis occurred only in group 1 (cartilage regeneration ratio: mean± standard deviation, 0.97± 0.60), whereas the cartilage regeneration ratio was substantially lower in group 2 (0.10± 0.11), group 3 (0.08± 0.09), and group 4 (0.08± 0.14) (p= 0.004). Instead of chondrogenesis, osteogenesis was observed in the periosteal graft groups. No statistically significant differences were found in the amount of osteogenesis or chondrogenesis between groups 2 and 3. Group 4 showed fibrous tissue accumulation in the defect area. CONCLUSION: Periosteal grafts showed weak chondrogenic potential in an ear cartilage defect model of rabbits; instead, they exhibited osteogenesis, irrespective of their embryological origin.

Neural representations of ensemble coding in the occipital and parietal cortices.

The human visual system is able to extract summary statistics from sets of similar items, but the underlying neural mechanism remains poorly understood. Using functional magnetic resonance imaging (fMRI) and an encoding model, we examined how the neural representation of ensemble coding is constructed by manipulating the task-relevance of ensemble features. We found a gradual increase in orientation-selective responses to the mean orientation of multiple stimuli along the visual hierarchy only when these orientations were task-relevant. Such responses to the ensemble orientation were present in the extrastriate area, V3, even when the mean orientation was not task-relevant, indicating that the ensemble representation can co-exist with the task-relevant individual feature representation. Ensemble orientations were also represented in frontal regions, but those representations were robust only when each mean orientation was linked to a motor response dimension. Together, our findings suggest that the neural representation of the ensemble percept is formed by pooling signals at multiple levels of the visual processing stream.

Novel, user-friendly landmarks for localizing Baxter's nerve: A cadaveric study.

INTRODUCTION: Identification of Baxter's nerve (BN) has proven challenging for less experienced practitioners using ultrasonography due to a lack of adequate landmarks. This study aimed to establish novel, user-friendly anatomical landmarks and to describe useful structures to localize BN. MATERIALS AND METHODS: We examined 10 fresh cadaveric feet and identified the interobserver agreement of measuring three surface landmarks: the most medially protruded point on the medial malleolus (P), the navicular tuberosity (Q), and the center of the calcaneus (B). Next, 24 fresh cadaveric feet were used to identify the point of BN entry into the quadratus plantae (QP) muscle, which corresponds to the proximal BN impingement site. The rectangular coordinate system consisted of the origin (point P), X-axis, extension line P-Q, and Y-axis (the perpendicular line to the X-axis). To consider various foot sizes, the X and Y values were divided by the P-Q length and were designated as the ratios X and Y. RESULTS: Points P and Q showed smaller interobserver differences than that of point B. Ratios X and Y were 61.25 and 99.80%, respectively, for the QP. BN arose from the lateral plantar nerve in 20 of 24 specimens. The adjacent vessel was <3 mm from the entrapment site of BN in 20 of 24 specimens. CONCLUSION: New landmarks will improve the precision of localizing the entrapment site of BN and will provide advanced guidelines for podiatric patients.

Simultaneous estimation procedure reveals the object-based, but not space-based, dependence of visual working memory representations.

Visual working memory (VWM) allows us to actively represent a limited amount of visual information in mind. Although its severe capacity limit is widely accepted, researchers disagree on the nature of its representational unit. Object-based theories argue that VWM organizes feature representations into integrated representations, whereas feature-based theories argue that VWM represents visual features independently. Supporting a feature-based account of VWM, recent studies have demonstrated that features comprising an object can be forgotten independently. Although evidence of feature-based forgetting invalidates a pure object-based account of VWM that assumes perfect integration of feature representations, it is possible that feature representations may be organized in a dependent manner on the basis of objects when they exist in memory. Furthermore, many previous studies prompted participants to recall object features independently by sequentially displaying a response probe for each feature (i.e., sequential estimation procedure), and this task demand might have promoted the independence of feature representations in VWM. To test these possibilities, we created a novel task to simultaneously capture the representational quality of two features of the same object (i.e., simultaneous estimation procedure) and tested their dependence across the entire spectrum of representational quality. Here, we found that the quality of feature representations within the same object covaried reliably in both sequential and simultaneous estimation procedures, but this representational dependence was statistically stronger in the simultaneous estimation procedure than in the sequential estimation procedure. Furthermore, we confirmed that neither the shared spatial location nor simultaneous estimation of two features was sufficient to induce representational dependence in VWM. Thus, our results demonstrate that feature representations in VWM are organized in a dependent manner on the basis of objects, but the degree of dependence can vary based on the current task demand.

Electrophysiological Evidence for Distinct Proactive Control Mechanisms in a Stop-Signal Task: An Individual Differences Approach.

Proactive control reflects a sustained, top-down maintenance of a goal representation prior to task-related events, whereas reactive control reflects a transient, bottom-up goal reactivation in response to them. We designed a manual stop-signal task to isolate electrophysiological signals specifically involved in proactive control. Participants performed a simple choice reaction time task but had to withhold their response to an infrequent stop signal, resulting in go- and stop-signal trials. We manipulated the stop-signal probability (30% vs. 10%) over different blocks of trials so that different proactive control levels were sustained within each block. The behavioral results indicated that most participants proactively changed their behaviors. The reaction times in the go trials increased and the number of response errors in the stop-signal trials decreased. However, those two behavioral measures did not correlate: individuals with an increased delayed reaction did not necessarily manifest a higher decrease in response errors in the stop-signal trials. To isolate the proactive control signal, we obtained event-related potentials (ERPs) locked to an uninformative fixation onset and compared the signals between the two stop-signal probability conditions. We found that the ERPs at the left hemisphere were more negatively shifted with the increasing stop-signal probability. Moreover, ERP differences obtained from a set of electrodes in the left hemisphere accounted for the changes in response errors in the stop-signal trials but did not explain the changes in reaction times of the go trials. Together, the behavioral and electrophysiological results suggest that proactive control mechanisms reducing erroneous responses of the stop-signal trials are different from mechanisms slowing reaction times of the go trials.

Similarity-based clusters are representational units of visual working memory.

We investigated whether clustering based on feature similarity improves the representational quality of visual working memory (VWM). We hypothesized that similar items are organized into clusters, and their recall precision increases with fewer clusters because of reduced memory load. In a series of 6 experiments, participants remembered orientations or colors of several stimuli and estimated the orientation (color) of cued item(s). We measured recall bias to identify whether items formed cluster(s) and measured recall precision to determine the effect of clustering on the representational quality of VWM. In Experiments 1 and 2, orientation similarity was manipulated to partition stimuli into 1, 2, or 3 clusters. In Experiment 3, we varied both the number of stimuli and their similarities such that 5 items were summarized into a smaller number of clusters than 3 items. We consistently found that similar items formed a cluster, and that the precision of the individual items increased with fewer clusters regardless of the number of items. We also observed the same clustering effects using color stimuli when participants were to remember items' colors (Experiment 4). However, a task-irrelevant feature was not potent enough to cluster items and did not increase the precision (Experiment 5). In Experiment 6, we varied item similarity and found that response errors were correlated within the same cluster but not across different clusters. Taken together, these results suggest that clusters formed by similar items can impact the representation of VWM; thus, acting as one of representational units of VWM. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Ensemble representations reveal distinct neural coding of visual working memory.

We characterized the population-level neural coding of ensemble representations in visual working memory from human electroencephalography. Ensemble representations provide a unique opportunity to investigate structured representations of working memory because the visual system encodes high-order summary statistics as well as noisy sensory inputs in a hierarchical manner. Here, we consistently observe stable coding of simple features as well as the ensemble mean in frontocentral electrodes, which even correlated with behavioral indices of the ensemble across individuals. In occipitoparietal electrodes, however, we find that remembered features are dynamically coded over time, whereas neural coding of the ensemble mean is absent in the old/new judgment task. In contrast, both dynamic and stable coding are found in the continuous estimation task. Our findings suggest that the prefrontal cortex holds behaviorally relevant abstract representations while visual representations in posterior and visual areas are modulated by the task demands.

Slow Temporal Dynamics of Motion-Induced Brightness Shift Reveals Impact of Adaptation.

Brightness of an object is determined by various factors including ambient illumination, surface reflectance of the object, and spatial and temporal relation between the object and its surrounding context. Recently, it has been demonstrated that the motion of an object alters its own and nearby object's appearance such as brightness and color. This study aims to unveil mechanisms of the motion-induced brightness shift by measuring its temporal dynamics. We found that the motion-induced brightness shift occurred instantaneously with the motion onset when the motion was introduced abruptly. However, the brightness of a stationary object was altered gradually by a nearby moving object in about 2 s time window when the stationary dot was introduced abruptly. Two distinct temporal dynamics (slow vs. fast) of the motion-induced brightness shift demonstrate that both slow neural adaptation and fast neural normalization processes determine the brightness shift induced by the object's motion.

Angiolytic laser stripping versus CO2 laser microflap excision for vocal fold leukoplakia: Long-term disease control and voice outcomes.

BACKGROUND AND PURPOSE: Vocal fold leukoplakia, white plaque on the epithelium, has the potential for malignant transformation regardless of dysplasia grade. It is treated with different laser types (CO2 or angiolytic) and various techniques (vaporization, stripping, or excision); however, only a few studies exist regarding comparative laser surgery results. This study was conducted to investigate clinical outcomes of CO2 versus angiolytic laser microdissection with regard to long-term disease control and voice preservation in vocal fold leukoplakia. MATERIALS AND METHODS: Seventy patients with vocal fold leukoplakia treated by CO2 or angiolytic laser (pulsed dye laser or potassium titanyl phosphate) were identified retrospectively. Data regarding patient characteristics, treatment details, treatment outcomes including disease control (recurrence and progression) and the Voice Handicap Index, GRBAS scale, and acoustics were evaluated. The mean follow-up duration after initial treatment was 32 ± 26 months. RESULTS: The study group comprised 14 patients who underwent CO2 laser microflap excision and 56 who underwent angiolytic laser stripping. Of the patients treated with CO2 laser, 11 (79%) had no recurrence and three (21%) showed recurrent leukoplakia, of which one patient (7%) showed histologic grade progression. Of patients who underwent angiolytic laser stripping, 12 had disease recurrence (21%), among whom three (5%) showed disease progression. Laser surgery type, disease extent, and histologic grade showed no significant differences in recurrence or progression rates. The postoperative Voice Handicap Index significantly improved (P = .03) and the G score significantly decreased (P < .001) in the angiolytic laser treatment group. In contrast, the Voice Handicap Index increased postoperatively in the CO2 laser group (P = .046). CONCLUSIONS: The long-term recurrence or progression rates were not significantly different between angiolytic and CO2 laser treatment. The angiolytic laser stripping group showed better voice preservation compared with the CO2 laser group. Angiolytic laser stripping is suggested as an effective treatment option for vocal fold leukoplakia with comparable disease control and better voice preservation.

Effect of different muscle contraction interventions using an isokinetic dynamometer on muscle recovery following muscle injury.

The objective of the present study was to examine the effects of different muscle contraction interventions using isokinetic dynamometers on the muscle recovery after muscle injury caused by eccentric exercise. A total of 28 healthy male adults participated in the present study and each subject was randomly assigned to eccentric muscle contraction (EC, n=7), concentric muscle contraction (CC, n=7), both eccentric and concentric muscle contraction (BEC, n=7), and control (CON, n=7) groups after performing eccentric exercise. In all groups, except the control group, a different type of muscle contraction intervention was applied repeatedly for 24-96 hr after eccentric exercise, and maximum strength, muscle soreness, and creatine kinase (CK) levels were measured. The results showed a significant association between time and group, with respect to maximum strength (P<0.05), muscle soreness (P<0.001), and CK (P<0.001) after eccentric exercise. Moreover, BEC group showed faster muscle recovery than other groups. In conclusion, implementing active strategies such as performing BEC using an isokinetic dynamometer after eccentric exercise may be effective in facilitating muscle recovery.

Prolonged Interruption of Cognitive Control of Conflict Processing Over Human Faces by Task-Irrelevant Emotion Expression.

As documented by Darwin 150 years ago, emotion expressed in human faces readily draws our attention and promotes sympathetic emotional reactions. How do such reactions to the expression of emotion affect our goal-directed actions? Despite the substantial advance made in the neural mechanisms of both cognitive control and emotional processing, it is not yet known well how these two systems interact. Here, we studied how emotion expressed in human faces influences cognitive control of conflict processing, spatial selective attention and inhibitory control in particular, using the Eriksen flanker paradigm. In this task, participants viewed displays of a central target face flanked by peripheral faces and were asked to judge the gender of the target face; task-irrelevant emotion expressions were embedded in the target face, the flanking faces, or both. We also monitored how emotion expression affects gender judgment performance while varying the relative timing between the target and flanker faces. As previously reported, we found robust gender congruency effects, namely slower responses to the target faces whose gender was incongruent with that of the flanker faces, when the flankers preceded the target by 0.1 s. When the flankers further advanced the target by 0.3 s, however, the congruency effect vanished in most of the viewing conditions, except for when emotion was expressed only in the flanking faces or when congruent emotion was expressed in the target and flanking faces. These results suggest that emotional saliency can prolong a substantial degree of conflict by diverting bottom-up attention away from the target, and that inhibitory control on task-irrelevant information from flanking stimuli is deterred by the emotional congruency between target and flanking stimuli.

Peripheral target identification performance modulates eye movements.

We often shift our eyes to an interesting stimulus, but it is important to inhibit that eye movement in some environments (e.g., a no-look pass in basketball). Here, we investigated participants' ability to inhibit eye movements when they had to process a peripheral target with a requirement to maintain strict fixation. An array of eight letters composed of four characters was briefly presented and a directional cue was centrally presented to indicate the target location. The stimulus onset asynchrony (SOA) between the cue and the stimulus array was chosen from six values, consisting of pre-cue conditions (-400 and -200ms), a simultaneous cue condition (0ms), and post-cue conditions (200, 400, and 800ms). We found the following: 1) participants shifted their eyes toward the cued location even though the stimulus array was absent at the onset of eye movements, but the eye movement amplitude was smaller than the actual location of the target; 2) eye movements occurred approximately 150ms after the onset of stimulus array in the pre-cue conditions and 250ms after cue onset in the simultaneous and post-cue conditions; and 3) eye movement onsets were delayed and their amplitudes were smaller in correct trials than incorrect trials. These results indicate that the inhibitory process controlling eye movements also compete for cognitive resources like other cognitive processes.

Motion Alters Color Appearance.

Chromatic induction compellingly demonstrates that chromatic context as well as spectral lights reflected from an object determines its color appearance. Here, we show that when one colored object moves around an identical stationary object, the perceived saturation of the stationary object decreases dramatically whereas the saturation of the moving object increases. These color appearance shifts in the opposite directions suggest that normalization induced by the object's motion may mediate the shift in color appearance. We ruled out other plausible alternatives such as local adaptation, attention, and transient neural responses that could explain the color shift without assuming interaction between color and motion processing. These results demonstrate that the motion of an object affects both its own color appearance and the color appearance of a nearby object, suggesting a tight coupling between color and motion processing.

Distinct neural mechanisms for spatially lateralized and spatially global visual working memory representations.

Visual working memory (VWM) allows humans to actively maintain a limited amount of information. Whereas previous electrophysiological studies have found that lateralized event-related potentials (ERPs) track the maintenance of information in VWM, recent imaging experiments have shown that spatially global representations can be read out using the activity across the visual cortex. The goal of the present study was to determine whether both lateralized and spatially global electrophysiological signatures coexist. We first show that it is possible to simultaneously measure lateralized ERPs that track the number of items held in VWM from one visual hemfield and parietooccipital α (8-12 Hz) power over both hemispheres indexing spatially global VWM representations. Next, we replicated our findings and went on to show that this bilateral parietooccipital α power as well as the contralaterally biased ERP correlate of VWM carries a signal that can be used to decode the identity of the representations stored in VWM. Our findings not only unify observations across electrophysiology and imaging techniques but also suggest that ERPs and α-band oscillations index different neural mechanisms that map on to lateralized and spatially global representations, respectively.

Less Is More: Semantic Information Survives Interocular Suppression When Attention Is Diverted.

UNLABELLED: The extent of unconscious semantic processing has been debated. It is well established that semantic information is registered in the absence of awareness induced by inattention. However, it has been debated whether semantic information of invisible stimuli is processed during interocular suppression, a procedure that renders one eye's view invisible by presenting a dissimilar stimulus to the other eye. Inspired by recent evidence demonstrating that reduced attention attenuates interocular suppression, we tested a counterintuitive hypothesis that attention withdrawn from the suppressed target location facilitates semantic processing in the absence of awareness induced by interocular suppression. We obtained an electrophysiological marker of semantic processing (N400 component) while human participants' spatial attention was being manipulated with a cueing paradigm during interocular suppression. We found that N400 modulation was absent when participants' attention was directed to the target location, but present when diverted elsewhere. In addition, the correlation analysis across participants indicated that the N400 amplitude was reduced with more attention being directed to the target location. Together, these results indicate that inattention attenuates interocular suppression and thereby makes semantic processing available unconsciously, reconciling conflicting evidence in the literature. We discuss a tight link among interocular suppression, attention, and conscious awareness. SIGNIFICANCE STATEMENT: Interocular suppression offers a powerful means of studying the extent of unconscious processing by rendering a salient stimulus presented to one eye invisible. Here, we provide evidence that attention is a determining factor for unconscious semantic processing. An electrophysiological marker for semantic processing (N400 component) was present when attention was diverted away from the suppressed stimulus but absent when attention was directed to that stimulus, indicating that inattention facilitates unconscious semantic processing during the interocular suppression. Although contrary to the common sense assumption that attention facilitates information processing, this result is in accordance with recent studies showing that attention modulates interocular suppression but is not necessary for semantic processing. Our finding reconciles the conflicting evidence and advances theories of consciousness.

Grouping Influences Output Interference in Short-term Memory: A Mixture Modeling Study.

Output interference is a source of forgetting induced by recalling. We investigated how grouping influences output interference in short-term memory. In Experiment 1, the participants were asked to remember four colored items. Those items were grouped by temporal coincidence as well as spatial alignment: two items were presented in the first memory array and two were presented in the second, and the items in both arrays were either vertically or horizontally aligned as well. The participants then performed two recall tasks in sequence by selecting a color presented at a cued location from a color wheel. In the same-group condition, the participants reported both items from the same memory array; however, in the different-group condition, the participants reported one item from each memory array. We analyzed participant responses with a mixture model, which yielded two measures: guess rate and precision of recalled memories. The guess rate in the second recall was higher for the different-group condition than for the same-group condition; however, the memory precisions obtained for both conditions were similarly degraded in the second recall. In Experiment 2, we varied the probability of the same- and different-group conditions with a ratio of 3 to 7. We expected output interference to be higher in the same-group condition than in the different-group condition. This is because items of the other group are more likely to be probed in the second recall phase and, thus, protecting those items during the first recall phase leads to a better performance. Nevertheless, the same pattern of results was robustly reproduced, suggesting grouping shields the grouped items from output interference because of the secured accessibility. We discussed how grouping influences output interference.