Biases in hand perception are driven by somatosensory computations, not a distorted hand model.

To sense and interact with objects in the environment, we effortlessly configure our fingertips at desired locations. It is therefore reasonable to assume that the underlying control mechanisms rely on accurate knowledge about the structure and spatial dimensions of our hand and fingers. This intuition, however, is challenged by years of research showing drastic biases in the perception of finger geometry.1,2,3,4,5 This perceptual bias has been taken as evidence that the brain's internal representation of the body's geometry is distorted,6 leading to an apparent paradox regarding the skillfulness of our actions.7 Here, we propose an alternative explanation of the biases in hand perception-they are the result of the Bayesian integration of noisy, but unbiased, somatosensory signals about finger geometry and posture. To address this hypothesis, we combined Bayesian reverse engineering with behavioral experimentation on joint and fingertip localization of the index finger. We modeled the Bayesian integration either in sensory or in space-based coordinates, showing that the latter model variant led to biases in finger perception despite accurate representation of finger length. Behavioral measures of joint and fingertip localization responses showed similar biases, which were well fitted by the space-based, but not the sensory-based, model variant. The space-based model variant also outperformed a distorted hand model with built-in geometric biases. In total, our results suggest that perceptual distortions of finger geometry do not reflect a distorted hand model but originate from near-optimal Bayesian inference on somatosensory signals.

Alpha oscillations reflect similar mapping mechanisms for localizing touch on hands and tools.

It has been suggested that our brain re-uses body-based computations to localize touch on tools, but the neural implementation of this process remains unclear. Neural oscillations in the alpha and beta frequency bands are known to map touch on the body in external and skin-centered coordinates, respectively. Here, we pinpointed the role of these oscillations during tool-extended sensing by delivering tactile stimuli to either participants' hands or the tips of hand-held rods. To disentangle brain responses related to each coordinate system, we had participants' hands/tool tips crossed or uncrossed at their body midline. We found that midline crossing modulated alpha (but not beta) band activity similarly for hands and tools, also involving a similar network of cortical regions. Our findings strongly suggest that the brain uses similar oscillatory mechanisms for mapping touch on the body and tools, supporting the idea that body-based neural processes are repurposed for tool use.

The mobilization and transport of newly fixed carbon are driven by plant water use in an experimental rainforest under drought.

Non-structural carbohydrates (NSCs) are building blocks for biomass and fuel metabolic processes. However, it remains unclear how tropical forests mobilize, export, and transport NSCs to cope with extreme droughts. We combined drought manipulation and ecosystem 13CO2 pulse-labeling in an enclosed rainforest at Biosphere 2, assessed changes in NSCs, and traced newly assimilated carbohydrates in plant species with diverse hydraulic traits and canopy positions. We show that drought caused a depletion of leaf starch reserves and slowed export and transport of newly assimilated carbohydrates below ground. Drought effects were more pronounced in conservative canopy trees with limited supply of new photosynthates and relatively constant water status than in those with continual photosynthetic supply and deteriorated water status. We provide experimental evidence that local utilization, export, and transport of newly assimilated carbon are closely coupled with plant water use in canopy trees. We highlight that these processes are critical for understanding and predicting tree resistance and ecosystem fluxes in tropical forest under drought.

Wave damping by giant kelp, Macrocystis pyrifera.

BACKGROUND AND AIMS: The increased likelihood and severity of storm events has brought into focus the role of coastal ecosystems in provision of shoreline protection by attenuating wave energy. Canopy-forming kelps, including giant kelp (Macrocystis pyrifera), are thought to provide this ecosystem service, but supporting data are extremely limited. Previous in situ examinations relied mostly on comparisons between nominally similar sites with and without kelp. Given that other factors (especially seafloor bathymetry and topographic features) often differ across sites, efforts to isolate the effects of kelp on wave energy propagation confront challenges. In particular, it can be difficult to distinguish wave energy dissipation attributable to kelp from frictional processes at the seabed that often covary with the presence of kelp. Here, we use an ecological transition from no kelp to a full forest, at a single site with static bathymetry, to resolve unambiguously the capacity of giant kelp to damp waves. METHODS: We measured waves within and outside rocky reef habitat, in both the absence and the presence of giant kelp, at Marguerite Reef, Palos Verdes, CA, USA. Nested within a broader kelp restoration project, this site transitioned from a bare state to one supporting a fully formed forest (density of 8 stipes m-2). We quantified, as a function of incident wave conditions, the decline in wave energy flux attributable to the presence of kelp, as waves propagated from outside and into reef habitat. KEY RESULTS: The kelp forest damped wave energy detectably, but to a modest extent. Interactions with the seabed alone reduced wave energy flux, on average, by 12 ±â€…1.4 % over 180 m of travel. The kelp forest induced an additional 7 ±â€…1.2 % decrease. Kelp-associated declines in wave energy flux were slightly greater for waves of longer periods and smaller wave heights. CONCLUSIONS: Macrocystis pyrifera forests have a limited, albeit measurable, capacity to enhance shoreline protection from nearshore waves. Expectations that giant kelp forests, whether extant or enhanced through restoration, have substantial impacts on wave-induced coastal erosion might require re-evaluation.

A Somatosensory Computation That Unifies Limbs and Tools.

It is often claimed that tools are embodied by their user, but whether the brain actually repurposes its body-based computations to perform similar tasks with tools is not known. A fundamental computation for localizing touch on the body is trilateration. Here, the location of touch on a limb is computed by integrating estimates of the distance between sensory input and its boundaries (e.g., elbow and wrist of the forearm). As evidence of this computational mechanism, tactile localization on a limb is most precise near its boundaries and lowest in the middle. Here, we show that the brain repurposes trilateration to localize touch on a tool, despite large differences in initial sensory input compared with touch on the body. In a large sample of participants, we found that localizing touch on a tool produced the signature of trilateration, with highest precision close to the base and tip of the tool. A computational model of trilateration provided a good fit to the observed localization behavior. To further demonstrate the computational plausibility of repurposing trilateration, we implemented it in a three-layer neural network that was based on principles of probabilistic population coding. This network determined hit location in tool-centered coordinates by using a tool's unique pattern of vibrations when contacting an object. Simulations demonstrated the expected signature of trilateration, in line with the behavioral patterns. Our results have important implications for how trilateration may be implemented by somatosensory neural populations. We conclude that trilateration is likely a fundamental spatial computation that unifies limbs and tools.

Value-consistent rehabilitation is associated with long-term psychological flexibility and quality of life after traumatic brain injury.

Meaningful steps have been taken toward using holistic approaches in outpatient rehabilitation for traumatic brain injury (TBI) (i.e., treating the whole individual); however, research and practice continue to disproportionately focus on adapting to physical and cognitive changes. Research suggests treatment focusing on individual values may be important for psychological adjustment after TBI. The current study sought to explore individual values across multiple life domains in those with TBI as well as what values outpatient rehabilitation was helpful for, and to examine discrepancies between these factors (i.e., value-consistent rehabilitation) in relation to important long-term treatment outcomes. 215 adults with a history of TBI who had participated in outpatient rehabilitation completed online surveys assessing how consistent outpatient rehabilitation was with individual values, psychological flexibility, and quality of life. The life domains with the greatest discrepancies between individual importance and rehabilitation helpfulness were spirituality, intimate relations, and family relations. Greater value-consistent rehabilitation was associated with higher levels of psychological flexibility and quality of life beyond demographics and injury characteristics. Our findings provide further support in favour of holistic, client-centred approaches that are facilitated by neurological rehabilitation programs.

Arthroscopic Removal of Extra-Articular Foreign Bodies From the Shoulder: Inside-Out Technique.

Arthroscopic shoulder surgery can be performed for retrieval of bullets and retained metallic fragments in the glenohumeral and subacromial spaces. Previous case reports and case series have demonstrated the effectiveness of an arthroscopic approach over an open procedure, as it is less invasive, allows for improved inspection and documentation of the joint surfaces and periarticular structures, and potentially leads to a faster recovery. An arthroscopic approach for extracting foreign bodies from both the quadrilateral space and the posterior extra-articular space by first accessing the glenohumeral space has yet to be described. This inside-out technique may afford surgeons the potential for improved visualization and less morbidity compared with a traditional open posterior approach. We report a technique for an arthroscopic inside-out approach for removal of extra-articular foreign bodies retained in either the quadrilateral space or the posterior extra-articular space.

Biological modification of coastal pH depends on community composition and time.

Biological processes play important roles in determining how global changes manifest at local scales. Primary producers can absorb increased CO2 via daytime photosynthesis, modifying pH in aquatic ecosystems. Yet producers and consumers also increase CO2 via respiration. It is unclear whether biological modification of pH differs across the year, and, if so, what biotic and abiotic drivers underlie temporal differences. We addressed these questions using the intensive study of tide pool ecosystems in Alaska, USA, including quarterly surveys of 34 pools over 1 year and monthly surveys of five pools from spring to fall in a second year. We measured physical conditions, community composition, and changes in pH and dissolved oxygen during the day and night. We detected strong temporal patterns in pH dynamics. Our measurements indicate that pH modification varies spatially (between tide pools) and temporally (across months). This variation in pH dynamics mirrored changes in dissolved oxygen and was associated with community composition, including both relative abundance and diversity of benthic producers and consumers, whose role differed across the year, particularly at night. These results highlight the importance of the time of year when considering the ways that community composition influences pH conditions in aquatic ecosystems.

Longitudinal assessment of mental health after a flood: roles of social support, hope, recovery stressors, and prior lifetime trauma.

OBJECTIVES: Severe weather events have mental health consequences for survivors that may change over time. We assessed post-flood mental health longitudinally in three groups of mostly middle-aged and older adults who varied in current and prior severe weather experiences. METHOD: Predictors of central interest were age, perceived social support, state hope (including agency and pathways), recovery stressors, and prior lifetime trauma. Criterion variables included symptoms of depression, post-traumatic stress disorder (PTSD), and worry. RESULTS: Analyses of variance yielded significant Disaster Exposure Group x Wave interactions for depression and PTSD symptoms. Those with flooded homes and properties had elevated symptoms at Wave 1 which were reduced at Wave 2. Older age was associated with fewer symptoms of depression, PTSD, and worry. Recovery stressors and lifetime trauma predicted more PTSD symptoms. Greater agency predicted less PTSD and depression symptoms, whereas pathways predicted less worry. CONCLUSION: These data show that mental health symptoms may decrease over time for those directly impacted by severe flooding. State hope appears to contribute to better mental health after exposure to a devastating flood. Implications for understanding the dynamic relationships among risk variables and positive factors that promote post-disaster mental health in the years after a flood are considered.

A horizon for haptic perception.

The spatial limits of sensory acquisition (its sensory horizon) are a fundamental property of any sensorimotor system. In the present study, we sought to determine whether there is a sensory horizon for the human haptic modality. At first blush, it seems obvious that the haptic system is bounded by the space where the body can interact with the environment (e.g., the arm span). However, the human somatosensory system is exquisitely tuned to sensing with tools-blind-cane navigation being a classic example of this. The horizon of haptic perception therefore extends beyond body space, but to what extent is unknown. We first used neuromechanical modeling to determine the theoretical horizon, which we pinpointed as 6 m. We then used a psychophysical localization paradigm to behaviorally confirm that humans can haptically localize objects using a 6-m rod. This finding underscores the incredible flexibility of the brain's sensorimotor representations, as they can be adapted to sense an object many times longer than the user's own body.NEW & NOTEWORTHY There are often spatial limits to where an active sensory system can sample information from the environment. Hand-held tools can extend human haptic perception beyond the body, but the limits of this extension are unknown. We used theoretical modeling and psychophysics to determine these spatial limits. We find that the ability to spatially localize objects through a tool extends at least 6 m beyond the user's body.

Resilience as a moderator of depression and anxiety: a bidimensional approach to predictors of subjective cognition in older adults.

OBJECTIVES: Subjective cognitive complaints (SCCs) have shown to be useful predictors of objective cognitive decline in older adults. Though psychopathology symptoms (e.g. depression, anxiety) have been linked to SCCs, little is known about the influence of positive psychology factors (e.g. resilience) on these complaints. The current study aimed to determine whether resilience predicts SCCs, and whether greater resilience moderates (or lessens) the effect of negative mental health symptoms on SCCs. METHODS: Four hundred twenty-eight adults aged 60 years or older (M = 67.6, SD = 5.9) were recruited to participate in an online Qualtrics survey study. Surveys included assessed psychological resilience [University of Washington Resilience Scale 8-item short form (UWRS-8)], depression [Geriatric Depression Scale (GDS-15)], anxiety [Geriatric Anxiety Scale (GAS-30)], and SCCs [Perceived Deficits Questionnaire-Depression (PDQ-D); Barkley Deficits in Executive Functioning Scale-Short Form (BDEFS-SF)]. RESULTS: Although greater resilience was only independently associated with less complaints on BDEFS total scores, resilience moderated (i.e. reduced) the negative effects of depression and anxiety on PDQ-D retrospective memory and planning subscales as well as BDEFS-SF total scores. Resilience also moderated (i.e. reduced) the negative effect of anxiety on PDQ-D total scores. CONCLUSION: With resilience lessening the effect of depression and anxiety on SCCS, our findings suggest positive psychological factors may be useful for understanding the prevalence of complaints. Future research should seek to replicate these findings and investigate relationships between additional positive psychological factors and cognitive health in old age including the use of both objective and subjective assessments of cognition.

Religiosity and Social Support Predict Resilience in Older Adults After a Flood.

In this study, we examined religiosity and social support as predictors of resilience after a devastating flood. Three flood exposure groups of primarily middle-aged and older adults were compared: (1) non-flooded adults as controls, (2) once-flooded adults with structural damage to homes and property in the 2016 flood, and (3) twice-flooded adults who had relocated inland because of prior catastrophic losses in the 2005 Hurricanes Katrina and Rita and then flooded again in 2016. Resilience was assessed using the Connor-Davidson Resilience Scale (CD-RISC). Correlation analyses confirmed that older age was correlated with higher religiosity, charitable work done for others, and resilience. Regression analyses indicated that religious beliefs and coping, social support, and charitable work done for others were associated with higher levels of resilience, whereas flood damage was unrelated to resilience. Implications for current views on post-disaster adversity and resilience in later life are discussed.

Settling the Score: Can CPT-3 Embedded Validity Indicators Distinguish Between Credible and Non-Credible Responders Referred for ADHD and/or SLD?

OBJECTIVE: The purpose of the present study was to further investigate the clinical utility of individual and composite indicators within the CPT-3 as embedded validity indicators (EVIs) given the discrepant findings of previous investigations. METHODS: A total of 201 adults undergoing psychoeducational evaluation for ADHD and/or Specific Learning Disorder (SLD) were divided into credible (n = 159) and non-credible (n = 42) groups based on five criterion measures. RESULTS: Receiver operating characteristic curves (ROC) revealed that 5/9 individual indicators and 2/4 composite indicators met minimally acceptable classification accuracy of ≥0.70 (AUC = 0.43-0.78). Individual (0.16-0.45) and composite indicators (0.23-0.35) demonstrated low sensitivity when using cutoffs that maintained specificity ≥90%. CONCLUSION: Given the lack of stability across studies, further research is needed before recommending any specific cutoff be used in clinical practice with individuals seeking psychoeducational assessment.

Preventing Drift through Continued Co-Design with a First Nations Community: Refining the Prototype of a Tiered FASD Assessment.

As part of the broader Yapatjarrathati project, 47 remote health providers and community members attended a two-day workshop presenting a prototype of a culturally-safe, tiered neurodevelopmental assessment that can identify fetal alcohol spectrum disorder (FASD) in primary healthcare. The workshop provided a forum for broad community feedback on the tiered assessment process, which was initially co-designed with a smaller number of key First Nations community stakeholders. Improvement in self-reported attendee knowledge, confidence, and perceived competence in the neurodevelopmental assessment process was found post-workshop, assessed through self-report questionnaires. Narrative analysis described attendee experiences and learnings (extracted from the workshop transcript), and workshop facilitator experiences and learnings (extracted from self-reflections). Narrative analysis of the workshop transcript highlighted a collective sense of compassion for those who use alcohol to cope with intergenerational trauma, but exhaustion at the cyclical nature of FASD. There was a strong desire for a shared responsibility for First Nations children and families and a more prominent role for Aboriginal Health Workers in the assessment process. Narrative analysis from workshop facilitator reflections highlighted learnings about community expertise, the inadvertent application of dominant cultural approaches throughout facilitation, and that greater emphasis on the First Nation's worldview and connection to the community was important for the assessment process to be maintained long-term. This study emphasised the benefit of continued co-design to ensure health implementation strategies match the needs of the community.

Examining heterogeneity in depression symptoms and associations with cognition and everyday function in MCI.

INTRODUCTION: Although there is some evidence that different symptoms of depression have differential effects on cognition in older adults, these relationships remain understudied in older adults with mild cognitive impairment (MCI). METHOD: Older adults (>50 years old) were classified as having MCI by Alzheimer's Disease Research Centers (ADRCs). Exploratory factor analyses and factor mixture modeling were used to determine depression symptom classes. Classes were then compared across different domains of cognition (i.e., memory, attention, language, and executive function) and informant-rated everyday function. RESULTS: Analyses revealed six, distinct symptom classes (i.e., somatic symptoms, severely depressed, anhedonic symptoms, cognitive symptoms, minimally depressed, and low life satisfaction symptoms). Classes significantly varied on all measures of cognition and everyday function. In particular, the anhedonic class often showed the most substantial decline (on par with the severely depressed class), while the low life satisfaction class often showed the least (on par with the minimally depressed class). CONCLUSIONS: To our knowledge, this is the first study to examine the relationship between depression symptom profiles and cognitive and everyday function in those with MCI. Our findings show that depression symptoms greatly differ in their associations with cognitive and everyday function. It may be beneficial for clinicians to specifically note if patients with MCI are reporting anhedonic and somatic symptoms of depression specifically.

Reach planning with someone else's hand.

To investigate the relationship between the sense of body ownership and motor control, we capitalized on a rare bizarre disorder wherein another person's hand is misattributed to their own body, i.e., a pathological form of embodiment (E+). Importantly, despite E+ is usually associated with motor deficits, we had the opportunity to test two E+ patients with spared motor function, thus able to perform a reaching task. Crucially, these patients had proprioceptive deafferentation, allowing us to purely isolate the embodiment-dependent effect from proprioception-dependent ones that are usually associated in experimental manipulations of body ownership in healthy participants. Previous evidence suggests that the reaching movement vector is attracted towards an embodied hand during the rubber hand illusion (RHI). However, these results are confounded by the spared proprioception, whose modulation alone could explain the effects on reach planning. The neuropsychological approach employed here provides unambiguous evidence about the role of body ownership in reach planning. Indeed, three brain-damaged patients with proprioceptive deafferentation, two E+ and a well-matched control patient without pathological embodiment (E-), and 10 age-matched healthy controls underwent a reaching task wherein they had to reach for a target from a fixed starting point, while an alien hand (the co-experimenter's) was placed on the table. Irrespective of proprioception, damaged in all patients, only in E+ patients reaching errors were significantly more shifted consistently with the pathological belief, i.e., as if they planned movements from the position of the alien (embodied) hand, as compared to controls. Furthermore, with an additional experiment on healthy participants, we demonstrated that reaching errors observed during the RHI correlate with the changes in ownership. In conclusion, our neuropsychological approach suggests that when planning a reach, we do so from where our owned hand is and not from its physical location.

Monitoring Bivalve Behavior and Physiology in the Laboratory and Field Using Open-Source Tools.

Bivalve molluscs have been the focus of behavioral and physiological studies for over a century, due in part to the relative ease with which their traits can be observed. The author reviews historical methods for monitoring behavior and physiology in bivalves, and how modern methods with electronic sensors can allow for a number of parameters to be measured in a variety of conditions using low-cost components and open-source tools. Open-source hardware and software tools can allow researchers to design and build custom monitoring systems to sample organismal processes and the environment, systems that can be tailored to the particular needs of a research program. The ability to leverage shared hardware and software can streamline the development process, providing greater flexibility to researchers looking to expand the number of traits they can measure, the frequency and duration of sampling, and the number of replicate devices they can afford to deploy.

Detection of Damage-Activated Metacaspase Activity by Western Blot in Plants.

Metacaspases are cysteine proteases that are present in plants, protists, fungi, and bacteria. Previously, we found that physical damage, e.g., pinching with forceps or grinding on liquid nitrogen of plant tissues, activates Arabidopsis thaliana METACASPASE 4 (AtMCA4). AtMCA4 subsequently cleaves PROPEP1, the precursor pro-protein of the plant elicitor peptide 1 (Pep1). Here, we describe a protein extraction method to detect activation of AtMCA4 by Western blot with antibodies against endogenous AtMCA4 and a PROPEP1-YFP fusion protein. It is important to (1) keep plant tissues at all times on liquid nitrogen prior to protein extraction, and (2) denature the protein lysate as fast as possible, as metacaspase activation ensues quasi immediately because of tissue damage inherent to protein extraction. In theory, this method can serve to detect damage-induced alterations of any protein-of-interest in any organism for which antibodies or fusion proteins are available, and hence, will greatly aid the study of rapid damage-activated proteolysis in the future.