Choice Points Research Articles

A Step Towards the Future of Role-Playing Games: The SpyFeet Mobile RPG Project

Meaningful choice has often been identified as a key component in a player's engagement with an interactive narrative, but branching stories require tremendous amounts of hand-authored content, in amounts that increase exponentially rather than linearly as more choice points are added. Previous approaches to reducing authorial burden for computer RPGs have relied on creating better tools to manage existing unwieldy structures of quests and dialogue trees. We hypothesize that reducing authorial burden and increasing agency are two sides of the same coin, requiring specific advancements in two related areas of design and technology research: (1) dynamic story management architecture that represents story events abstractly and allows story elements to be selected and re-ordered in response to player choices, and (2) dynamic dialogue generation to allow a single story event to be revealed differently by different characters and in the context of dynamic relationships between those characters and the player. This paper describes SpyFeet, a playable prototype of a storytellingsystem designed to test this hypothesis.

The hippocampus is functionally connected to the striatum and orbitofrontal cortex during context dependent decision making

Many of our everyday actions are only appropriate in certain situations and selecting the appropriate behavior requires that we use current context and previous experience to guide our decisions. The current study examined hippocampal functional connectivity with prefrontal and striatal regions during a task that required participants to make decisions based on the contextual retrieval of overlapping sequential representations. Participants learned four sequences comprised of six faces each. An overlapping condition was created by having two sequences with two identical faces as the middle images. A non-overlapping condition contained two sequences that did not share any faces between them. Hippocampal functional connectivity was assessed during the presentation period and at the critical choice, where participants had to make a contextually dependent decision. The left hippocampus showed significantly increased functional connectivity with dorsal and ventral striatum and anterior cingulate cortex during the presentation period of the overlapping compared to the non-overlapping condition after participants knew the sequences. At the critical choice point of the overlapping condition, the left hippocampus showed stronger functional connectivity with the orbitofrontal cortex. These functional connectivity results suggest that the hippocampus may play a role in decision making by predicting the possibilities of what might come next, allowing orbitofrontal and striatal regions to evaluate the expected choice options in order to make the correct action at the choice point.

The core planar cell polarity gene prickle interacts with flamingo to promote sensory axon advance in the Drosophila embryo

The atypical cadherin Drosophila protein Flamingo and its vertebrate homologues play widespread roles in the regulation of both dendrite and axon growth. However, little is understood about the molecular mechanisms that underpin these functions. Whereas flamingo interacts with a well-defined group of genes in regulating planar cell polarity, previous studies have uncovered little evidence that the other core planar cell polarity genes are involved in regulation of neurite growth. We present data in this study showing that the planar cell polarity gene prickle interacts with flamingo in regulating sensory axon advance at a key choice point — the transition between the peripheral nervous system and the central nervous system. The cytoplasmic tail of the Flamingo protein is not required for this interaction. Overexpression of another core planar cell polarity gene dishevelled produces a similar phenotype to prickle mutants, suggesting that this gene may also play a role in regulation of sensory axon advance.

Memory Modulates Journey-Dependent Coding in the Rat Hippocampus

Neurons in the rat hippocampus signal current location by firing in restricted areas called place fields. During goal-directed tasks in mazes, place fields can also encode past and future positions through journey-dependent activity, which could guide hippocampus-dependent behavior and underlie other temporally extended memories, such as autobiographical recollections. The relevance of journey-dependent activity for hippocampal-dependent memory, however, is not well understood. To further investigate the relationship between hippocampal journey-dependent activity and memory, we compared neural firing in rats performing two mnemonically distinct but behaviorally identical tasks in the plus maze: a hippocampus-dependent spatial navigation task and a hippocampus-independent cue response task. While place, prospective, and retrospective coding reflected temporally extended behavioral episodes in both tasks, memory strategy altered coding differently before and after the choice point. Before the choice point, when discriminative selection of memory strategy was critical, a switch between the tasks elicited a change in a field's coding category, so that a field that signaled current location in one task coded pending journeys in the other task. After the choice point, however, when memory strategy became irrelevant, the fields preserved coding categories across tasks, so that the same field consistently signaled either current location or the recent journeys. Additionally, on the start arm, firing rates were affected at comparable levels by task and journey; on the goal arm, firing rates predominantly encoded journey. The data demonstrate a direct link between journey-dependent coding and memory and suggest that episodes are encoded by both population and firing rate coding.

Trail Marking and Abandonment of Depleted Feeding Sites by the Caterpillars of Eutachyptera psidii (Lepidoptera: Lasiocampidae)

The caterpillars of Eutachytptera psidii (Lepidoptera: Lasiocampidae) mark trails between their nest and distant feeding sites with a trail pheromone secreted from the ventral surfaces of their last abdominal segments. The threshold sensitivity to artificial trails prepared from an hexane extract of the pheromone was 0.75 × 10−3 caterpillar-equivalents per cm of trail. In tests of trail-specificity involving four other social species, the caterpillars responded only to trails prepared from a pheromone extract of the closely related genus Gloveria. Tests were conducted to determine the efficiency with which colonies abandon exhausted feeding sites in favor of new food finds. On their first forays after their food sources were experimentally moved from established feeding sites to new sites, 67.5 ± 3.6% of all the evening’s activity occurred on pathways leading to the previously established sites. During their next two forays, 86.3 ± 3.7% and 92.1 ± 2.0% of all activity occurred on pathways leading to the new sites. Efficient abandonment of exhausted feeding sites is attributed to the persistence of the trail pheromone, differential marking of new and old pathways and to the caterpillar’s ability to discern trail strength and to choose stronger over weaker trails at choice points.

Vocational Psychology at the Fork in the Road: Staying the Course or Taking the Road Less Traveled

In response to the question posed in this special issue of the Journal of Career Assessment regarding the next big question in vocational psychology, this article poses that the field is at a critical fork in the road. The choice point for vocational psychology is to continue to create knowledge and services for middle-class populations with some degree of choice in their lives or to expand our inclusiveness to include people without as much volition about education, training, and work. In advocating for the road less traveled, some of the challenges and benefits that may result from examining the work lives of the poor and unemployed are reviewed. Selected contributions that vocational psychology can add to the discourse in unemployment and poverty are outlined.

N‐cadherin regulates primary motor axon growth and branching during zebrafish embryonic development

N-cadherin is a classical type I cadherin that contributes to the formation of neural circuits by regulating growth cone migration and the formation of synaptic contacts. This study analyzed the role of N-cadherin in primary motor axons growth during development of the zebrafish (Danio rerio) embryo. After exiting the spinal cord, primary motor axons migrate ventrally through a common pathway and form the first neuromuscular junction with the muscle pioneer cells located at the horizontal myoseptum, which serves as a choice point for cell-type-specific pathway selection. Analysis of N-cadherin mutants (cdh2(hi3644Tg) ) and embryos injected with N-cadherin antisense morpholinos showed primary motor axons extending aberrant axonal branches at the choice point in ∼40% of the somitic hemisegments and an ∼150% increase in the number of branches per axon length within the ventral myotome. Analysis of individual axons trajectories showed that the caudal (CaP) and rostral (RoP) motor neurons axons formed aberrant branches at the choice point that abnormally extended in the rostrocaudal axis and ventrally to the horizontal myoseptum. Expression of a dominant-interfering N-cadherin cytoplasmic domain in primary motor neurons caused some axons to stall abnormally at the horizontal myoseptum and to impair their migration into the ventral myotome. However, in N-cadherin-depleted embryos, the majority of primary motor axons innervated their appropriate myotomal territories, indicating that N-cadherin regulates motor axon growth and branching without severely affecting the mechanisms that control axonal target selection.

Prolegomenon to norms in branching space–times

Earlier (collaborative) work postulated that agency is essentially indeterministic, and finds a home in “branching times” (BT). BT is built on world-wide but momentary events called “moments” structured by an indeterministic causal ordering. The notion of a “history” is defined as a suitable chain of moments; histories branch one from another at moments. Other earlier work, the essential points of which are summarized in Section 2, led to “branching space–times” (BST). BT moments are replaced in BST by local “point events,” and “histories” are redefined more realistically as a family of suitable space–time-like structures that branch from one another at point events. In BST one finds that “transitions” from initial events to outcome events—each properly defined—play a fundamental role as originating causes (causae causantes) and effects. This spatio-temporal-causal story provides, in Section 3, an objective foundation for an indeterministic theory of agents and choices amid BST (BSTAC), the key concepts of which are “life event,” “life history,” and “person,” the latter essentially involving alternate possibilities, some of which arise from free choices. Section 4 works out a concept of “choice point,” leading to a BST account of “agent α sees to outcome O,” which is more sophisticated than the stit concept of earlier work. Many-agent cooperation is considered in Section 5, with hints concerning message sending and receiving. A theory of norms in BST (BSTACN) that builds on the foregoing, and also on earlier work, is briefly adumbrated in Section 6.

Shared decision making: using health information technology to integrate patient choice into primary care.

Advances in shared decision making (SDM) have not successfully translated to practice. We describe our experience and lessons learned in translating an SDM process for primary care cardiovascular disease management. The SDM process operationalized recognized SDM elements using workflow modifications, a computerized patient questionnaire, an automated risk calculator to identify at-risk patients, a web-based tool for patients to choose interventions, automated feedback on the personalized benefits of choices, and a web-based tool for providers to view patient risk, patient choice, and expert advice. Although medication was typically the intervention resulting in the greatest risk reduction, the majority of patients preferred dietary and other lifestyle changes. Patients generally favored the opportunity to make and communicate choices. However, providers only viewed patient choice data in 20% of the encounters. Translation of the SDM process was successful for patients and the difference between patient choice and optimal risk reduction points to the importance of engaging in an SDM process. Lack of engagement by providers may be due to "alert fatigue" or to the failure of the SDM process to improve efficiency in the office visit.

Effects of pharmacological manipulations of NMDA-receptors on deliberation in the Multiple-T task

Both humans and non-human animals have the ability to navigate and make decisions within complex environments. This ability is largely dependent upon learning and memory processes, many of which are known to depend on NMDA-sensitive receptors. When humans come to difficult decisions they often pause to deliberate over their choices. Similarly, rats pause at difficult choice points. This behavior, known as vicarious trial and error (VTE), is hippocampally dependent and entails neurophysiological representations of expectations of future outcomes in hippocampus and downstream structures. In order to determine the dependence of VTE behaviors on NMDA-sensitive receptors, we tested rats on a Multiple-T choice task with a reward-delivery reversal known to elicit VTE. Rats under the influence of NMDA-receptor antagonists (CPP) showed a significant reduction in VTE, particularly at the reward reversal, implying a role for NMDA-sensitive receptors in the generation of vicarious trial and error behaviors.

Modelling a Decision Maker's Preferences: Testing for Relevance and Application Development

The need for developing models in the tourism and hospitality industry which identify and make use of a decision maker's preferences has been demonstrated extensively in the works of Brown et al (2002) and Israeli and Brown (2004), as well as others (Ingold and Yeoman, 1997). In this study, the authors examine historical data of Israeli hotels in order to demonstrate empirically the need for these models and to determine which model best fits the empirical data. Three preference-based pricing models are tested, built with indifference curves to analyse the two-attribute case of room rate versus occupancy. These models differ from standard ones in that the decision maker's actual choices for specific budget scenarios are built directly into them. These constrained choice points are built into a table and are used to create an entire pricing schedule based on the preference ratio thus determined. The first model uses an unconstrained desired point and assumes that managers find rate and occupancy to be perfectly substitutable at all budget constraints. The second model assumes linear fractional substitutability and alters the ratio for specific constrained choice points (Israeli and Brown, 2004). The third model assumes perfect complementarity at each constrained choice point and assumes a consistent ratio for each constrained choice segment (Brown, 2004). The heuristic nature of the models makes statistical analysis of their validity difficult, but is thus attempted in any case. The motivation behind this test is to determine which model can best be used to evaluate behaviour and performance in a future study.

Lineage Divergence at the First TCR-Dependent Checkpoint: Preferential γδ and Impaired αβ T Cell Development in Nonobese Diabetic Mice

The first TCR-dependent checkpoint in the thymus determines αβ versus γδ T lineage fate and sets the stage for later T cell differentiation decisions. We had previously shown that early T cells in NOD mice that are unable to rearrange a TCR exhibit a defect in checkpoint enforcement at this stage. To determine if T cell progenitors from wild-type NOD mice also exhibit cell-autonomous defects in development, we investigated their differentiation in the Notch-ligand-presenting OP9-DL1 coculture system, as well as by analysis of T cell development in vivo. Cultured CD4 and CD8 double-negative cells from NOD mice exhibited major defects in the generation of CD4 and CD8 double-positive αβ T cells, whereas γδ T cell development from bipotent precursors was enhanced. Limiting dilution and single-cell experiments show that the divergent effects on αβ and γδ T cell development did not spring from biased lineage choice but from increased proliferation of γδ T cells and impaired accumulation of αβ T lineage double-positive cells. In vivo, NOD early T cell subsets in the thymus also show characteristics indicative of defective β-selection, and peripheral αβ T cells are poorly established in mixed bone marrow chimeras, contrasting with strong γδ T as well as B cell repopulation. Thus, NOD T cell precursors reveal divergent, lineage-specific differentiation abnormalities in vitro and in vivo from the first TCR-dependent developmental choice point, which may have consequences for subsequent lineage decisions and effector functions.

Preference of dairy cows: Indoor cubicle housing with access to a total mixed ration vs. access to pasture

Cattle are grazing animals so it is generally assumed that pasture is a welfare friendly system as it is natural and allows the expression of normal behaviour, which may be restricted indoors. However, high yielding dairy cows may not be able to fulfil their nutritional demands from grass alone resulting in them becoming hungry, compromising their welfare. As indoor housing and pasture may both have positive and negative effects on the welfare of dairy cattle a study was conducted to determine the preference of high genetic merit Holstein dairy cows ( n = 32) in mid to late lactation to be indoors or on pasture and to establish the factors that influenced their decision. Twice a day, after milking, cows were taken to a choice point equidistant (48 m) from indoor housing and pasture, where cows chose whether to go indoors or to pasture. After their initial choice, cows could then move between indoors and pasture until the next milking. Indoors, a total mixed ration (TMR) was available ad libitum. At pasture, sward dry matter (DM) was maintained between 1800 and 3000 kg DM/ha. Decision at the choice point and time spent in each location were recorded. To determine what influenced the cow's decision, behaviour, weather conditions, milk yield, lameness, body condition score (BCS) and liveweight were recorded. From the choice point cows chose to go indoors almost twice as often as to pasture (66.2 ± 5.02% vs. 33.8 ± 5.02%, respectively) which was significantly different from 100% ( P < 0.001), 50% ( P = 0.004) and 0% ( P < 0.001), and spent more time indoors compared to pasture (91.9 ± 2.33% vs. 8.1 ± 2.33%, respectively) which was significantly different from 100% ( P = 0.001), 50% ( P < 0.001) and 0% ( P < 0.001). Milk yield affected preference ( P = 0.005) with high yielding cows (>26.9 kg/day; n = 12) spending more time indoors than low yielding dairy cows (≤26.9 kg/day; n = 12), and there was a tendency for cows with a higher BCS (>2.7; n = 12) to spend more time at pasture ( P = 0.058). Of the weather conditions rainfall influenced preference ( P = 0.015) with cows spending more time indoors on days when it rained. Indoor and outdoor temperature–humidity index (THI), lameness and liveweight had no effect on preference. The results indicate that the cows in this study had a partial preference to be indoors which is likely to be influenced by the TMR, allowing high yielding cows to meet their nutritional demands. However, this partial preference does not mean that pasture is not important for the welfare of dairy cows.

A narrative of an action research study in preschool: choice points and their implications for professional and organisational development

Against the background of Swedish preschool's historical and traditional functions in Swedish society, this article focuses on some of the choice points and their implications for professional and organisational development in preschool. By combining feminist pragmatism and feminist action research, some analytical points are made regarding the significance of organisational settings and the limitations they can have on the professional practices within the organisational setting. The preschool teachers in this study show that pedagogical change is possible, although it takes time and is not necessarily endorsed by municipal employers. The role of action researchers is described in terms of positions and ethics. The latter is presented as particularly important.

Environmental Cues that Affect Knowing: A Case Study in a Public Hospital Building

Hospital buildings can be described as sophisticated public areas due to their functional organizations’ complexity and architectural configuration. Although these buildings generally cover all the functional requirements, quite often they are not able to face the psychological needs of patients and their companions. The research which is presented in this article focuses on the “perceptive memories” of companions, during their visits in the hospital. The main aim of the study is to describe the “visual characteristics” of the environment that helps the users to “know” the building and affect the “legibility”. The case study was carried out in one of the largest public hospitals in Istanbul, the CAPA Clinical Faculty, which has a distinctive architectural form. The symmetrical plans of the building provided an opportunity to compare data gathered from the different departments of the hospital which have very similar configurations but different wall colours, signage systems, functions, lighting design, floor coverings and landmarks. 41 participants were engaged in a questionnaire task, which contained open-ended questions, and photographs taken from similar points and presented the same perspectives that were chosen on purpose. The participants were asked to choose their departments from the picture boards and explain the reason for their choice by describing the physical characteristics of the environment. In the literature, these mentioned points are called “choice points”, places where people get information from the environment and make decisions about their movements. As a result of the study, the analysis of the data provided support that people need environmental cues for describing and knowing their environment. The results essentially present the fact that legibility decreases in conditions in which there are fewer environmental cues. The research also suggests that the time spent in the hospital plays a significant role in the task performance. People who spent more time in the hospital tended to use different descriptive words from others. One of the most significant purposes of architectural design is to create environments in which users are psychologically satisfied with the human-environment interaction system. It is essential that the organization of the physical environment satisfies peoples’ psychological needs, particularly in public places such as hospital buildings, where people don’t have time and energy to waste.

A forward genetic screen with a thalamocortical axon reporter mouse yields novel neurodevelopment mutants and a distinct emx2 mutant phenotype

BackgroundThe dorsal thalamus acts as a gateway and modulator for information going to and from the cerebral cortex. This activity requires the formation of reciprocal topographic axon connections between thalamus and cortex. The axons grow along a complex multistep pathway, making sharp turns, crossing expression boundaries, and encountering intermediate targets. However, the cellular and molecular components mediating these steps remain poorly understood.ResultsTo further elucidate the development of the thalamocortical system, we first created a thalamocortical axon reporter line to use as a genetic tool for sensitive analysis of mutant mouse phenotypes. The TCA-tau-lacZ reporter mouse shows specific, robust, and reproducible labeling of thalamocortical axons (TCAs), but not the overlapping corticothalamic axons, during development. Moreover, it readily reveals TCA pathfinding abnormalities in known cortical mutants such as reeler. Next, we performed an unbiased screen for genes involved in thalamocortical development using random mutagenesis with the TCA reporter. Six independent mutant lines show aberrant TCA phenotypes at different steps of the pathway. These include ventral misrouting, overfasciculation, stalling at the corticostriatal boundary, and invasion of ectopic cortical cell clusters. An outcross breeding strategy coupled with a genomic panel of single nucleotide polymorphisms facilitated genetic mapping with small numbers of mutant mice. We mapped a ventral misrouting mutant to the Emx2 gene, and discovered that some TCAs extend to the olfactory bulbs in this mutant. Mapping data suggest that other lines carry mutations in genes not previously known for roles in thalamocortical development.ConclusionsThese data demonstrate the feasibility of a forward genetic approach to understanding mammalian brain morphogenesis and wiring. A robust axonal reporter enabled sensitive analysis of a specific axon tract inside the mouse brain, identifying mutant phenotypes at multiple steps of the pathway, and revealing a new aspect of the Emx2 mutant. The phenotypes highlight vulnerable choice points and latent tendencies of TCAs, and will lead to a refined understanding of the elements and interactions required to form the thalamocortical system.See Commentary: http://www.biomedcentral.com/1741-7007/9/1

The Role of Theory in Furthering Evidence-Based Practice

This issue of HERD presents a fascinating array of research ranging from the development of substantive findings, to measurement development, to meta-analysis. All of these research purposes are exceptionally important for the development of a robust research base for evidence-based design. In these articles, the authors note the limitations of their work in regard to generalizability, measurement problems, and so forth, all of which remain symptomatic of much research in this domain. Simultaneously, the studies reflect a willingness to push the domain ahead, whether in terms of research strategy (e.g., retrospective data analysis or meta-analysis) or instrument development. There is much to learn from this collection of articles; a brief discussion of each follows.Brooks and colleagues conducted a two-part, highly exploratory pilot study regarding the design of nightstands. The first study involved 28 participants in assisted living or rehabilitation settings who were interviewed in regard to their use and perceptions of nightstands. The second study involved interviews of 36 university students and 36 older adults regarding perceptions of a smart design for a nightstand or side table. One should be circumspect about drawing conclusions from such an exploratory study because of sample size, problems of construct validity, and issues associated with research design.Lorenz and Dreher conducted a retrospective study that compared private and shared hospital rooms with regard to the occurrence of falls, hospital-acquired infection (HAI) rates, and risk for social isolation. Unfortunately the sample was extremely small (five falls in 166 patients; nine occurrences of HAI); thus, empirical conclusions in the study should be considered with caution. The authors acknowledge this limitation.Foureur and colleagues provide an update on the ongoing development of the Birth Unit Design Spatial Evaluation Tool (BUDSET), designed to assess the optimality of birth settings. The intriguing conceptual model underlying the development of this tool posits that optimal birth settings both facilitate effective communication and decrease patient and staff stress, which are mediated by the design of the birth unit as well as the model of care employed. The authors identify four critical spatial domains for birthing units: responses to the fear cascade, and facility characteristics, aesthetics, and support. Each of these is manifested by multiple characteristics, which are assessed through specific observable phenomena. The tool could discriminate between labor ward settings and birth centers, but the internal validity of half of the characteristics was unacceptable, suggesting the need for significant refinement of the tool.Algase and colleagues report on a cross-sectional observational study that compares two approaches to assessing the experiential attribute of crowding in long-term care settings. Crowding was assessed in two ways: first, by a simple count of people present in the room or area being observed; second, by means of the Long-Term Care Crowding Index (LTC-CI) developed by the authors. This study highlights different levels of crowding between nursing homes and assisted living facilities as well as variations between types of room and time of day. The LTC-CI advances the body of knowledge by attempting to account for density and to identify the role proximity plays in the assessment of crowding.Marquardt's contribution is a meta-analysis of the literature on spatial wayfinding for people with dementia. This extensive literature review makes clear a tangible connection between neuroscience and architectural design by suggesting that the optimization of spatial configuration and environmental cueing affects the orientation processes of people with dementia. Marquardt determines that limiting choice points, making environmental amenities visually accessible, and reinforcing wayfinding through appropriate environmental cues and signage are likely to provide a more supportive wayfinding environment. …

Effects of acute and repeated nicotine administration on delay discounting in Lewis and Fischer 344 rats

Biological differences may underlie individual differences in impulsive behavior, such as choice for a smaller, more immediate reinforcer over a larger, more delayed reinforcer. Repeated exposure to drugs of abuse may have different effects on such behavior. To evaluate the acute and repeated effects of nicotine on impulsive choice, two strains of rats that have been shown to differ in impulsive choice were tested in a delay-discounting paradigm. Eight Lewis and eight Fischer 344 rats were allowed to choose between one food pellet delivered immediately and three food pellets delivered after a delay. The delay systematically increased in blocks of trials within each session, and the delay value at which the choice for the two alternatives was equal (i.e. the indifference point) was interpolated. Effects of nicotine (0.1-1.0 mg/kg, subcutaneous) on percent choice and indifference points were determined during the acute-testing phase and during the redetermination of effects of each dose after at least 30 sessions of repeated 1.0 mg/kg nicotine exposure. The Lewis rats had shorter indifference points (i.e. made fewer larger-reinforcer choices) compared with the Fischer 344 rats. Acute nicotine administration increased the mean larger-reinforcer choices at the 0.3 mg/kg dose in the Lewis rats and at the 1.0 mg/kg dose in the Fischer 344 rats. After repeated exposure to nicotine, indifference points returned to near-baseline (predrug) levels for both the strains. Strain differences were observed in the rates of delay discounting, and nicotine may decrease the impulsive choice acutely, but this effect does not seem to be long lasting.

GDNF Acts as a Chemoattractant to Support ephrinA-Induced Repulsion of Limb Motor Axons

Despite the abundance of guidance cues in vertebrate nervous systems, little is known about cooperation between them. Motor axons of the lateral motor column (LMC(L)) require two ligand/receptor systems, ephrinA/EphA4 and glial cell line-derived neurotrophic factor (GDNF)/Ret, to project to the dorsal limb. Deletion of either EphA4 or Ret in mice leads to rerouting of a portion of LMC(L) axons to the ventral limb, a phenotype enhanced in EphA4;Ret double mutants. The guidance errors in EphA4 knockouts were attributed to the lack of repulsion from ephrinAs in the ventral mesenchyme. However, it has remained unclear how GDNF, expressed dorsally next to the choice point, acts on motor axons and cooperates with ephrinAs. Here we show that GDNF induces attractive turning of LMC(L) axons. When presented in countergradients, GDNF and ephrinAs cooperate in axon turning, indicating that the receptors Ret and EphA4 invoke opposite effects within the same growth cone. GDNF also acts in a permissive manner by reducing ephrinA-induced collapse and keeping the axons in a growth-competent state. This is the first example of two opposing cues promoting the same trajectory choice at an intermediate target.

Lessons in Collaboration, Four Years Post‐Katrina

Four action researchers present a case study of a project conducted by members of a national family therapy organization and members of a local family therapy institute, which describes their efforts to collaborate with local disaster recovery workers 2 years after Hurricane Katrina. The aim of the collaboration was to create a local action research team to study best practices that strengthen resilience after disaster. The authors discuss choice points and dilemmas faced in finding collaborative partners and in clarifying what constitutes an invitation to work in a community. The case study illuminates tensions and understandings between outsiders and a community still facing the long-term effects of a disaster.