Background: Socially anxious individuals are theorized to avoid social cues and engage in safety behaviors to prevent negative evaluation, which prevents disconfirmation of social fears. Cognitive models propose that this avoidance is driven by (1) self-focused attention (SFA) and (2) physiological arousal. Design: To examine these proposed mechanisms, we compared high socially anxious (HSA; n =29) and low socially anxious (LSA; n = 28) participants on a view-time task involving faces. Method: Participants engaged in a task in which they viewed socially threatening (i.e., disgust, anger) and nonthreatening (i.e., happy, neutral) faces. Results: Results revealed that HSA participants endorsed greater SFA during the view-time task and spent less time viewing angry, disgusted, and neutral facial expressions relative to LSA participants. Regression analyses revealed that arousal, as indexed by salivary ?-amylase, was a unique predictor of increased face-viewing time among HSA participants. In contrast, arousal predicted decreased face-viewing time among LSA participants. Conclusions: Findings underscore the need for further investigation of avoidance mechanisms in social anxiety.
Fumigation for nematode management in irrigated potato production systems of Idaho is widely practiced. Soil injection is the only labeled application method for 1,3-dichloropropene that is conventionally applied on a whole-field basis. Plant-parasitic nematode species exhibit spatially variable population densities that provide an opportunity to practice site-specific fumigation to reduce chemical usage and production costs. During 2002 to 2008, 62 fields intended for commercial potato production in eastern Idaho were sampled using a geo-referenced grid sampling system for plant-parasitic nematode population densities. In total, 4,030 grid samples were collected representing nearly 3,200 ha of commercial potato production. Collectively, 73% of the grid samples had Columbia root knot (CRN) (Meloidogyne chitwoodi) population densities below detectable levels. Site-specific fumigation is the practice of varying application rate of a fumigant based on nematode population density. In 2007, 640 ha of potato production were site-specific fumigated for CRN nematode control in eastern Idaho. On average, this practice resulted in a 30% reduction in chemical usage and production cost savings of $209/ha when 1,3-dichloropropene was used as the sole source of nematode suppression. Reductions in usage of 1,3-dichloropropene can exceed 50% if used in combination with a nonfumigant nematicide such as oxamyl. This combination approach can have production cost savings exceeding $200/ha. Based on farm-gate receipts and USDA inspections provided by potato producers from 2001 to 2011, potato tuber yield and quality have not been adversely affected using site-specific fumigation.
While several models of memory consolidation have previously associated hippocampal activity with declarative memory, there is now increasing evidence that the hippocampus also plays a crucial role in procedural memory. Here, we review recent human functional neuroimaging studies demonstrating that the hippocampus is involved in the acquisition and sleep-related consolidation of procedural memories, and motor sequence-based skills in particular. More specifically, we present evidence that hippocampal activity and its functional interactions with other brain structures, particularly competition with the striatum, contribute to initial learning of sequential motor behavior. Interestingly, these early cerebral representations in the hippocampus and striatum, which may interact through the prefrontal cortex, can even predict subsequent sleep-related memory consolidation processes. We propose that sleep can reorganize the activity within, as well as the functional interactions between, these structures, ultimately favoring overnight performance enhancement. Finally, we conclude by offering insights into the respective roles of these structures in procedural memory consolidation processes. We argue that, in the context of motor sequence memory consolidation, the hippocampal system triggers subsequent sleep-dependent performance enhancement whereas the striatal system is involved in the maintenance of the motor behavior over time.
As the worlds population ages, a deeper understanding of the relationship between aging and motor learning will become increasingly relevant in basic research and applied settings. In this context, this review aims to address the effects of age on motor sequence learning (MSL) and motor adaptation (MA) with respect to behavioral, neurological, and neuroimaging findings. Previous behavioral research investigating the influence of aging on motor learning has consistently reported the following results. First, the initial acquisition of motor sequences is not altered, except under conditions of increased task complexity. Second, older adults demonstrate deficits in motor sequence memory consolidation. And, third, although older adults demonstrate deficits during the exposure phase of MA paradigms, the aftereffects following removal of the sensorimotor perturbation are similar to young adults, suggesting that the adaptive ability of older adults is relatively intact. This paper will review the potential neural underpinnings of these behavioral results, with a particular emphasis on the influence of age-related dysfunctions in the cortico-striatal system on motor learning.
Special mass influenza vaccination programs of elementary school-aged children (ESAC) in some or all Maryland Counties were conducted during the falls of 2005-2007. From 3% to 46% of ESAC received live attenuated influenza vaccine during these county programs, which were in addition to routine influenza vaccination efforts conducted in county medical offices. Anonymous, all cause public school absentee data for all grades was available from 11 of Marylands 24 counties. Binomial regression was used to estimate associations between the percentage of children vaccinated in each county and the degree of increase in absenteeism rates during influenza outbreaks. We estimated that, for every 20% increase in vaccination rates for ESAC during these special programs, a 4% decrease in the rise in absentee rates occurred during influenza outbreak periods in both elementary and upper schools (P<0.05). These results suggest both direct and indirect benefits of influenza vaccination of young children.
Recent research has demonstrated that adaptation to a visuomotor distortion systematically influenced movements to auditory targets in adults and typically developing (TD) children, suggesting that the adaptation of spatial-to-motor transformations for reaching movements is multisensory (i.e., generalizable across sensory modalities). The multisensory characteristics of these transformations in children with developmental coordination disorder (DCD) have not been examined. Given that previous research has demonstrated that children with DCD have deficits in sensorimotor integration, these children may also have impairments in the formation of multisensory spatial-to-motor transformations for target-directed arm movements. To investigate this hypothesis, children with and without DCD executed discrete arm movements to visual and acoustic targets prior to and following exposure to an abrupt visual feedback rotation. Results demonstrated that the magnitudes of the visual aftereffects were equivalent in the TD children and the children with DCD, indicating that both groups of children adapted similarly to the visuomotor perturbation. Moreover, the influence of visuomotor adaptation on auditory-motor performance was similar in the two groups of children. This suggests that the multisensory processes underlying adaptation of spatial-to-motor transformations are similar in children with DCD and TD children.
Previous research investigating children with Developmental Coordination Disorder (DCD) has consistently reported increased intra- and inter-individual variability during motor skill performance. Statistically characterizing this variability is not only critical for the analysis and interpretation of behavioral data, but also may facilitate our understanding of the processes underlying DCD. Thus, the primary purpose of this research was to demonstrate the utility of a flexible statistical technique, a random coefficient model (RCM), that characterizes the increased intra- and inter-individual variability in children with and without DCD. We analyzed data from a sensorimotor adaptation task during which participants executed discrete aiming movements under conditions of rotated visual feedback. To highlight the advantages of this statistical approach, we contrasted the results from the RCM with those from a traditionally employed general linear model (GLM). The RCM revealed differences between the two groups of children that the GLM did not detect; and, characterized trajectories of change for each individual. The RCM provides researchers an opportunity to probe behavioral deficits at the individual level and may provide new insights into the behavioral heterogeneity in children with DCD.
To determine the influence of arousal on cerebral cortical dynamics and motor behavior, 58 channels of EEG were recorded in 13 college-age men (n=6) and women during an aiming task performed alone and in a social evaluation condition. Moderate arousal, as measured by heart rate, skin conductance, and self-reported mood, was induced during the social evaluation. In accord with the Yerkes-Dodson Hypothesis, which posits optimal performance during moderate arousal, improved performance (i.e., quality of the aiming trajectories) was observed. During social evaluation, changes in electroencephalogram dynamics included decreased coherence between the motor planning (Fz) and right temporal region (T4), increased coherence in the sensorimotor networks subserving the task, and increased local processing (gamma, 30-44 Hz) in the temporal regions. The results imply that moderate arousal promotes specific alterations in cortical dynamics that facilitate motor performance.
We studied the role of cocaine and amphetamine related transcript (CART) in regulating context induced reinstatement (renewal) of reward seeking. Rats were trained to respond for alcoholic beer in context A before extinction in context B. Rats were tested for responding in context A (ABA) and context B (ABB). Intracerebroventricular (ICV) infusions of the active fragment CART55-102 but not the inactive fragment CART1-27 before test prevented ABA renewal of extinguished responding. ICV CART55-102 had no effect on responding in the extinction context (ABB). ICV CART55-102 also altered the profile of behavioral responses observed on test in the training (ABA) but not extinction (ABB) context. These results identify a novel role for CART in preventing reinstatement of reward seeking.
Accurate and efficient sensorimotor behavior depends on precise localization of the body in space, which may be estimated using multiple sensory modalities (i.e., vision and proprioception). Although age-related differences in multisensory-motor integration across childhood have been previously reported, the extent to which age-related changes in unimodal functioning affect multisensory-motor integration is unclear. The purpose of the current study was to address this knowledge gap. Thirty-seven 7- to 13-year-old children moved their dominant hand in a target localization task to visual, proprioceptive, and concurrent visual and proprioceptive stimuli. During a subsequent experimental phase, we introduced a perturbation that placed the concurrent visual and proprioceptive stimuli in conflicting locations (incongruent condition) to determine the relative contributions of vision and proprioception to the multisensory estimate of target position. Results revealed age-related differences in the localization of incongruent stimuli in which the visual estimate of target position contributed more to the multisensory estimate in the younger children whereas the proprioceptive estimate was up-weighted in the older children. Moreover, above and beyond the effects of age, differences in proprioceptive functioning systematically influenced the relative contributions of vision and proprioception to the multisensory estimate during the incongruent trials. Specifically, improvements in proprioceptive functioning resulted in an up-weighting of proprioception, suggesting that the central nervous system of school-aged children utilizes information about unimodal functioning to integrate redundant sensorimotor inputs.
The extant developmental literature investigating age-related differences in the execution of aiming movements has predominantly focused on visuomotor coordination, despite the fact that additional sensory modalities, such as audition and somatosensation, may contribute to motor planning, execution, and learning. The current study investigated the execution of aiming movements toward both visual and acoustic stimuli. In addition, we examined the interaction between visuomotor and auditory-motor coordination as 5- to 10-yr-old participants executed aiming movements to visual and acoustic stimuli before and after exposure to a visuomotor rotation. Children in all age groups demonstrated significant improvement in performance under the visuomotor perturbation, as indicated by decreased initial directional and root mean squared errors. Moreover, children in all age groups demonstrated significant visual aftereffects during the postexposure phase, suggesting a successful update of their spatial-to-motor transformations. Interestingly, these updated spatial-to-motor transformations also influenced auditory-motor performance, as indicated by distorted movement trajectories during the auditory postexposure phase. The distorted trajectories were present during auditory postexposure even though the auditory-motor relationship was not manipulated. Results suggest that by the age of 5 yr, children have developed a multisensory spatial-to-motor transformation for the execution of aiming movements toward both visual and acoustic targets.
We examined whether the behavioral impairments in finger torque control evident in children with developmental coordination disorder (DCD) follow a delayed or different developmental trajectory compared with their typically developing peers.
The toxicity of chronic immunosuppressive agents required for organ transplant maintenance has prompted investigators to pursue approaches to induce immune tolerance. We developed an approach using a bioengineered mobilized cellular product enriched for hematopoietic stem cells (HSCs) and tolerogenic graft facilitating cells (FCs) combined with nonmyeloablative conditioning; this approach resulted in engraftment, durable chimerism, and tolerance induction in recipients with highly mismatched related and unrelated donors. Eight recipients of human leukocyte antigen (HLA)-mismatched kidney and FC/HSC transplants underwent conditioning with fludarabine, 200-centigray total body irradiation, and cyclophosphamide followed by posttransplant immunosuppression with tacrolimus and mycophenolate mofetil. Subjects ranged in age from 29 to 56 years. HLA match ranged from five of six loci with related donors to one of six loci with unrelated donors. The absolute neutrophil counts reached a nadir about 1 week after transplant, with recovery by 2 weeks. Multilineage chimerism at 1 month ranged from 6 to 100%. The conditioning was well tolerated, with outpatient management after postoperative day 2. Two subjects exhibited transient chimerism and were maintained on low-dose tacrolimus monotherapy. One subject developed viral sepsis 2 months after transplant and experienced renal artery thrombosis. Five subjects experienced durable chimerism, demonstrated immunocompetence and donor-specific tolerance by in vitro proliferative assays, and were successfully weaned off all immunosuppression 1 year after transplant. None of the recipients produced anti-donor antibody or exhibited engraftment syndrome or graft-versus-host disease. These results suggest that manipulation of a mobilized stem cell graft and nonmyeloablative conditioning represents a safe, practical, and reproducible means of inducing durable chimerism and donor-specific tolerance in solid organ transplant recipients.
Previous developmental research examining sensorimotor control of the arm in school-age children has demonstrated age-related improvements in movement kinematics. However, the mechanisms that underlie these age-related improvements are still unclear. This study hypothesized that changes in sensorimotor performance across childhood can be attributed, in part, to the development of state estimation, defined as estimates computed by the central nervous system, which specify both current and future hand positions and velocities (i.e., hand "state"). Two behavioral experiments were conducted, in which 6- to 12-year-old children and young adults executed goal-directed arm movements. Results from Experiment 1 revealed that young children (i.e., ?6-8 years) have less precise proprioceptive feedback for static (i.e., stationary) hand state estimation compared with older children (i.e., ?10-12 years), resulting in increased variability of target-directed reaching movements. Experiment 2 demonstrated that young children rely on delayed and unreliable state estimates during the execution of goal-directed hand movements (i.e., dynamic state estimation), resulting in both increased movement errors and directional variability. Collectively, these results suggest that improvements in sensorimotor behavior across childhood can be attributed, at least partially, to the development of both static and dynamic state estimation.
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