The effect of recreational cannabis legalization and commercialization on substance use, mental health, and injury: a systematic review

OBJECTIVE

To determine the effect of recreational cannabis legalization (RCL) and/or recreational cannabis commercialization (RCC) on emergency department (ED) visits, hospitalizations, and deaths due to substance use, injury, and mental health among those aged 11 years and older.

METHODS

A systematic review of six electronic databases up to February 1, 2023. Original, peer-reviewed articles with interrupted time series or before and after designs were included. Four independent reviewers screened articles and assessed risk of bias. Outcomes with 'critical' risk of bias were excluded. Protocol registered on PROSPERO (# CRD42021265183).

RESULTS

After screening and risk of bias assessment, 29 studies were included which examined ED visits or hospitalizations for cannabis use or alcohol (N = 10), opioid mortality (N = 3), motor vehicle fatalities or injury (N = 11), and intentional injury/mental health (N = 5). Rates or number of cannabis-related hospitalizations increased after RCL in Canada and the USA. Immediate increases in rates of cannabis-related ED visits were found after both RCL and RCC in Canada. Rates of traffic fatalities increased after RCL and RCC in certain jurisdictions in the USA.

CONCLUSIONS

RCL was associated with increased rates of cannabis-related hospitalizations. RCL and/or RCC was associated with increased rates of cannabis-related ED visits, consistently shown across sex and age groups. The effect on fatal motor vehicle incidents was mixed, with observed increases found after RCL and/or RCC. The effect of RCL or RCC on opioids, alcohol, intentional injury, and mental health is not clear. These results inform population health initiatives and international jurisdictions considering RCL implementation.

Evolutionary stability of social interaction rules in collective decision-making

Social animals can use the choices made by other members of their groups as cues in decision making. Individuals must balance the private information they receive from their own sensory cues with the social information provided by observing what others have chosen. These two cues can be integrated using decision making rules, which specify the probability to select one or other options based on the quality and quantity of social and non-social information. Previous empirical work has investigated which decision making rules can replicate the observable features of collective decision making, while other theoretical research has derived forms for decision making rules based on normative assumptions about how rational agents should respond to the available information. Here we explore the performance of one commonly used decision making rule in terms of the expected decision accuracy of individuals employing it. We show that parameters of this model which have typically been treated as independent variables in empirical model-fitting studies obey necessary relationships under the assumption that animals are evolutionarily optimised to their environment. We further investigate whether this decision making model is appropriate to all animal groups by testing its evolutionary stability to invasion by alternative strategies that use social information differently, and show that the likely evolutionary equilibrium of these strategies depends sensitively on the precise nature of group identity among the wider population of animals it is embedded within.

Police-led real-time surveillance system for suspected suicides in Great Britain

It has become increasingly apparent that rapidly available information about the occurrence of suicides is needed, particularly to support suicide prevention efforts. Concerns about the potential impact of the COVID-19 pandemic on vulnerability to suicide highlighted the need for such early data internationally. Here, we set out the nature, current status and content of a real-time suicide monitoring system in Great Britain (England, Scotland and Wales), and explore its potential to contribute to timely and targeted suicide prevention initiatives. We also discuss the challenges to successful implementation.

Nosocomial or not? A combined epidemiological and genomic investigation to understand hospital-acquired COVID-19 infection on an elderly care ward

Background

COVID-19 has the potential to cause outbreaks in hospitals. Given the comorbid and elderly cohort of patients hospitalized, hospital-acquired COVID-19 infection is often fatal. Pathogen genome sequencing is becoming increasingly important in infection prevention and control (IPC).

Aim

To inform the understanding of in-hospital SARS-CoV-2 transmission in order to improve IPC practices and to inform the future development of virological testing for IPC.

Methods

Patients detected COVID-19 positive by polymerase chain reaction on Ward A in April and May 2020 were included with contact tracing to identify other potential cases. Genome sequencing was undertaken for a subgroup of cases. Epidemiological, genomic, and cluster analyses were performed to describe the epidemiology and to identify factors contributing to the outbreak.

Findings

Fourteen cases were identified on Ward A. Contact tracing identified 16 further patient cases; in addition, eight healthcare workers (HCWs) were identified as being COVID-19 positive through a round of asymptomatic testing. Genome sequencing of 16 of these cases identified viral genomes differing by two single nucleotide polymorphisms or fewer, with further cluster analysis identifying two groups of infection (a five-person group and a six-person group).

Conclusion

Despite the temporal relationship of cases, genome sequencing identified that not all cases shared transmission events. However, 11 samples were found to be closely related and these likely represented in-hospital transmission. This included three HCWs, thereby confirming transmission between patients and HCWs.

How do you develop systems leadership in public health? Insights from a scoping study

OBJECTIVES

Systems leadership is widely acknowledged to be needed to address the many 'wicked issues' challenging public health systems. However, there is a lack of evidence on how to develop public health professionals into effective systems leaders. This study scoped the possibilities for developing the systems leadership capacity of public health specialists in England.

STUDY DESIGN

This was a mixed-methods qualitative scoping study design.

METHODS

The study involved three stages. In the first, a rapid literature review mapped key documents in three relevant areas: systems leadership theory and practice, the changing context of public health in the UK, and training and development for UK public health professionals. In the second, 29 stakeholders were consulted to understand the context and needs for systems leadership development in public health. A third phase involved stakeholders codesigning a potential development framework for the project commissioners.

RESULTS

Four main themes were identified: the nature and purpose of systems leadership; development needs and opportunities for public health specialists; the enabling environment; and wider contextual factors impacting public health.

CONCLUSIONS

Key principles of, and a framework for, a systems leadership development approach are identified, which could be applied to any public health system.

A Systematic Nomenclature for the Drosophila Ventral Nerve Cord

Drosophila melanogaster is an established model for neuroscience research with relevance in biology and medicine. Until recently, research on the Drosophila brain was hindered by the lack of a complete and uniform nomenclature. Recognizing this, Ito et al. (2014) produced an authoritative nomenclature for the adult insect brain, using Drosophila as the reference. Here, we extend this nomenclature to the adult thoracic and abdominal neuromeres, the ventral nerve cord (VNC), to provide an anatomical description of this major component of the Drosophila nervous system. The VNC is the locus for the reception and integration of sensory information and involved in generating most of the locomotor actions that underlie fly behaviors. The aim is to create a nomenclature, definitions, and spatial boundaries for the Drosophila VNC that are consistent with other insects. The work establishes an anatomical framework that provides a powerful tool for analyzing the functional organization of the VNC.

Genomic sequence analysis reveals diversity of Australian Xanthomonas species associated with bacterial leaf spot of tomato, capsicum and chilli

Background

The genetic diversity in Australian populations of Xanthomonas species associated with bacterial leaf spot in tomato, capsicum and chilli were compared to worldwide bacterial populations. The aim of this study was to confirm the identities of these Australian Xanthomonas species and classify them in comparison to overseas isolates. Analysis of whole genome sequence allows for the investigation of bacterial population structure, pathogenicity and gene exchange, resulting in better management strategies and biosecurity.

Results

Phylogenetic analysis of the core genome alignments and SNP data grouped strains in distinct clades. Patterns observed in average nucleotide identity, pan genome structure, effector and carbohydrate active enzyme profiles reflected the whole genome phylogeny and highlight taxonomic issues in X. perforans and X. euvesicatoria. Circular sequences with similarity to previously characterised plasmids were identified, and plasmids of similar sizes were isolated. Potential false positive and false negative plasmid assemblies were discussed. Effector patterns that may influence virulence on host plant species were analysed in pathogenic and non-pathogenic xanthomonads.

Conclusions

The phylogeny presented here confirmed X. vesicatoria, X. arboricola, X. euvesicatoria and X. perforans and a clade of an uncharacterised Xanthomonas species shown to be genetically distinct from all other strains of this study. The taxonomic status of X. perforans and X. euvesicatoria as one species is discussed in relation to whole genome phylogeny and phenotypic traits. The patterns evident in enzyme and plasmid profiles indicate worldwide exchange of genetic material with the potential to introduce new virulence elements into local bacterial populations.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5600-x) contains supplementary material, which is available to authorized users.

Abstract P6-13-01: MRI breast cancer screening compared to mammography in women with a familial risk: A multicenter randomized controlled trial

Background: Screening guidelines for women with a family history of breast cancer without a known causative gene mutation differ per country. No randomized controlled trial has been performed to assess the optimal screening strategy for these women.

Methods: In twelve centers, 1355 women aged 30–55 years with a cumulative lifetime risk of ≥20% without a BRCA1/2 mutation were randomized into two arms. From January 2011 until December 2017, women in the MRI-arm received yearly MRI-screening, clinical breast examination (CBE), and mammography every other year; and in the Mx-arm yearly mammography and CBE. Outcomes were number and stage of detected breast cancers, sensitivity, specificity and positive predictive value, and stratified by screening round and by mammographic density.

Results: After on average 4.3 screening rounds per woman, in the MRI-arm (N=675) compared to the Mx-arm (N=680) more breast cancers were detected (41 versus 14, p<0.001), invasive cancers were smaller (median size 8 versus 17 mm, p=0.006) and less often node positive (20% versus 71.4%, p=0.019)(Table). In the MRI-arm, sensitivity was slightly higher (95.1% versus 92.9%, p=1), and specificity significantly lower (82% versus 90.1%, p<0.001), compared to the Mx-arm. After two rounds, specificity improved for both modalities (87.1% for MRI; 93.0% for Mx; p<0.001) and no ≥T2 tumors or interval cancers occurred in the MRI-arm. All tumors ≥T2 were in the two highest density categories. MRI detected more small invasive tumors than Mx across all density categories.

Conclusions: In real-life practice the MRI-arm detected more, relevantly smaller, and far more often node negative tumors, and also at low density in women with a familial risk for breast cancer.

Table 1Characteristics of participating women at baseline and of the detected breast cancers, according to study armParticipantsMRI-arm n=675Mx-arm n=680MRI-arm vs. Mx-arm p-valueMean age yr ± SD44.6 ± 6.244.7 ± 6.3 Premenopausal512 (76%)505 (74%) Previous Mx ≤ 2 yr536 (79 %)542 (80%) Previous Mx > 2 years ago23 ( 3%)29 ( 4%) Previous MRI ≤ 2 years ago62 ( 9%)81 (12%) Previous MRI > 2 years ago91 (14%)89 (13%) BI-RADS density category*   I (entirely fat)88 (13%)92 (14%) II (scattered densities)248 (37%)229 (34%) III (heterogeneously dense)238 (35%)243 (36%) IV (extremely dense)98 (15%)102 (15%) Mean age at cancer detection49,6 ± 7.049,8 ± 4,70.74No cancer – no. (%)634 (94%)666 (98%) Invasive breast cancers – no. (%)25 (4%)7 (1%)<0.001 (noBC/inv BC/DCIS)DCIS – no. (%)16 (2%)7 (1%) Median size of invasive cancers8 mm17 mm0.006T1a/b15 (60%)1 (14%) T1c7 (28%)4 (57%)0.078 (T1a-b/T1c/≥ T2)≥ T23 (12%)2 (29%) Node pos5 (20%)5 (71%)0.019 (N+/-)Node negative20 (80%)2 (29%) DCIS grade 15 (31%)2 (29%) DCIS grade 28 (50%)4 (57%)1 (dcis gr1,2,3)DCIS grade 33 (19%)1 (14%) *Determined by radiologists, according to the fourth ACR BI-RADS edition

Citation Format: Tilanus-Linthorst MM, Saadatmand S, Geuzinge AH, Rutgers EJ, Mann R, de Roy van Zuidewijn DB, Zonderland HM, Tollenaar RA, Lobbes MB, Ausems MG, van 't Riet M, Hooning MJ, Mares-Engelbert I, Luiten EJ, Heijnsdijk EA, Verhoef C, Karssemeijer N, Oosterwijk JC, Obdeijn I-M, de Koning HJ. MRI breast cancer screening compared to mammography in women with a familial risk: A multicenter randomized controlled trial [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-13-01.

Doctors with Asperger's: the impact of a diagnosis

BACKGROUND

Asperger syndrome (AS) is part of a spectrum of disorders encompassing difficulties with social interaction that may result in specific educational needs for doctors in training. There is currently limited research on the impact of AS on working as a doctor.

METHODS

This is a qualitative study using semi-structured interviews to explore the perceptions of trainees diagnosed with AS following input from a professional support service, and the perspectives of the staff involved in their professional development.

FINDINGS

Receiving a diagnosis of AS was viewed as a double-edged sword, allowing the development of insight into lifelong difficulties, but also creating the potential for prejudice. Understanding AS traits provided an explanation for challenges in the workplace and therefore opportunities to find solutions. Understanding AS traits provided an explanation for challenges in the workplace DISCUSSION: This study explores the benefits and disadvantages of defining and labelling a specific professional support need for a group of trainees. It also reveals the need for improved awareness of AS amongst all clinical educators.

An unusual complication of nasolabial flap reconstruction

Squamous cell carcinoma is the most common carcinoma in the oral cavity. Resection of these cancers often requires reconstruction. Nasolabial flaps are a robust and reliable local flap that provide a satisfactory outcome. We report two cases where an epidermoid cyst developed within the scar of the nasolabial flap and review the literature.

Doctors with dyslexia: strategies and support

BACKGROUND

Looking beyond dyslexia as an individual doctor's issue requires adjusting a working environment to better serve the needs of doctors with dyslexia. With an increasing number of doctors disclosing dyslexia at medical school, how can educators best provide this support? Our research looks at the impact of dyslexia on clinical practice and the coping strategies used by doctors to minimise the effect.

METHODS

Qualitative data were collected from 14 doctors with dyslexia using semi-structured interviews and by survey. 'In situ' demonstration interviews were conducted in order to understand how dyslexia is managed in the workplace from first-hand experience. Employers and educators who have responsibility for meeting the needs of this group were also consulted.

RESULTS

Even in cases of doctors who had a diagnosis, they often did not disclose their dyslexia to their employer. Study participants reported having developed individual ways of coping and devised useful 'workarounds'. Support from employers comes in the form of 'reasonable adjustments', although from our data we cannot be sure that such adjustments contribute to an 'enabling' work environment. Supportive characteristics included the opportunity to shadow others and the time and space to complete paperwork on a busy ward. How can educators best provide support [for doctors with dyslexia]?

DISCUSSION

Doctors with dyslexia need to be helped to feel comfortable enough to disclose. Educators need to challenge any negative assumptions that exist as well as promote understanding about the elements that contribute to a positive working environment. As a result of the research there is now practice available for educators to identify evidence-based strategies and resources.

Quantification of Random Pore Structures of Porous Adsorbents

The structure of pore spaces in typical catalyst particles could often be described as being “not so much fabricated as thrown together”. Thus whilst for certain materials, such as zeolites, the microstructures are well defined and have a precise geometry, most materials when used in typical particulate form are at least partly composed of chaotically configured pore spaces. These random pore structures can be important in determining an adsorbent's performance, so it is necessary to define them quantitatively.

A heirarchy of approaches based upon developments from simple stochastic pore networks is described. A stochastic pore network is one in which simple pore segments form interconnecting networks within which pores can be either randomly or partly randomly distributed. Such stochastic networks can be characterised by mercury porosimetry and low-temperature gas adsorption. Interconnectivity and randomness affect the degree of hysteresis for both these techniques. For 3-D random pattern stochastic networks, it is possible to interpret sectioned SEM images using ‘random’ slices of particles subject to low melting point alloy visual porosimetry in order to arrive at measures of random pore structure. This ‘image analysis’ approach is being extended to 3-D image reconstruction of SEM sections using fractal surfaces in conjunction with randomly tortuous pores.

Association of previous injury and speed with running style and stride-to-stride fluctuations

Running-related injuries remain problematic among recreational runners. We evaluated the association between having sustained a recent running-related injury and speed, and the strike index (a measure of footstrike pattern, SI) and spatiotemporal parameters of running. Forty-four previously injured and 46 previously uninjured runners underwent treadmill running at 80%, 90%, 100%, 110%, and 120% of their preferred running speed. Participants wore a pressure insole device to measure SI, temporal parameters, and stride length (S(length)) and stride frequency (S(frequency)) over 2-min intervals. Coefficient of variation and detrended fluctuation analysis provided information on stride-to-stride variability and correlative patterns. Linear mixed models were used to compare differences between groups and changes with speed. Previously injured runners displayed significantly higher stride-to-stride correlations of SI than controls (P = 0.046). As speed increased, SI, contact time (T(contact)), stride time (T(stride)), and duty factor (DF) decreased (P < 0.001), whereas flight time (T(flight)), S(length), and S(frequency) increased (P < 0.001). Stride-to-stride variability decreased significantly for SI, T(contact), T(flight), and DF (P ≤ 0.005), as did correlative patterns for T(contact), T(stride), DF, S(length), and S(frequency) (P ≤ 0.044). Previous running-related injury was associated with less stride-to-stride randomness of footstrike pattern. Overall, runners became more pronounced rearfoot strikers as running speed increased.

The inferior turbinate flap: a novel technique for prosthetic preparation of a total rhinectomy defect

For total rhinectomy defects, the decision to proceed with a prosthetic versus surgical reconstruction is multifactorial, taking into account patient risk factors, availability of donor tissues, the need for tumor surveillance, and personal preferences. When a prosthetic approach is chosen, the reconstructive surgeon is tasked with preparing the defect to maximize prosthetic retention and prevent ulcerations. Stable bone coverage is critical to achieve this aim. Although skin grafting has been described previously for bone coverage, the periosteum is often stripped. We present a novel use of the inferior turbinate flap for preparation of rhinectomy defects that can be utilized regardless of the presence or absence of the periosteum and provides a more durable coverage than skin grafts.

A combinatorial regulatory signature controls terminal differentiation of the dopaminergic nervous system in C. elegans

Terminal differentiation programs in the nervous system are encoded by cis-regulatory elements that control the expression of terminal features of individual neuron types. We decoded the regulatory information that controls the expression of five enzymes and transporters that define the terminal identity of all eight dopaminergic neurons in the nervous system of the Caenorhabditis elegans hermaphrodite. We show that the tightly coordinated, robust expression of these dopaminergic enzymes and transporters ("dopamine pathway") is ensured through a combinatorial cis-regulatory signature that is shared by all dopamine pathway genes. This signature is composed of an Ets domain-binding site, recognized by the previously described AST-1 Ets domain factor, and two distinct types of homeodomain-binding sites that act in a partially redundant manner. Through genetic screens, we identified the sole C. elegans Distalless/Dlx ortholog, ceh-43, as a factor that acts through one of the homeodomain sites to control both induction and maintenance of terminal dopaminergic fate. The second type of homeodomain site is a Pbx-type site, which is recognized in a partially redundant and neuron subtype-specific manner by two Pbx factors, ceh-20 and ceh-40, revealing novel roles of Pbx factors in the context of terminal neuron differentiation. Taken together, we revealed a specific regulatory signature and cognate, terminal selector-type transcription factors that define the entire dopaminergic nervous system of an animal. Dopaminergic neurons in the mouse olfactory bulb express a similar combinatorial transcription factor collective of Ets/Dlx/Pbx factors, suggesting deep phylogenetic conservation of dopaminergic regulatory programs.

Signatures of the Z = 82 shell closure in α-decay process

In recent experiments at the velocity filter Separator for Heavy Ion reaction Products (SHIP) (GSI, Darmstadt), an extended and improved set of α-decay data for more than 20 of the most neutron-deficient isotopes in the region from lead to thorium was obtained. The combined analysis of this newly available α-decay data, of which the (186)Po decay is reported here, allowed us for the first time to clearly show that crossing the Z = 82 shell to higher proton numbers strongly accelerates the α decay. From the experimental data, the α-particle formation probabilities are deduced following the Universal Decay Law approach. The formation probabilities are discussed in the framework of the pairing force acting among the protons and the neutrons forming the α particle. A striking resemblance between the phenomenological pairing gap deduced from experimental binding energies and the formation probabilities is noted. These findings support the conjecture that both the N = 126 and Z = 82 shell closures strongly influence the α-formation probability.

Control of mitochondrial structure and function by the Yorkie/YAP oncogenic pathway

Mitochondrial structure and function are highly dynamic, but the potential roles for cell signaling pathways in influencing these properties are not fully understood. Reduced mitochondrial function has been shown to cause cell cycle arrest, and a direct role of signaling pathways in controlling mitochondrial function during development and disease is an active area of investigation. Here, we show that the conserved Yorkie/YAP signaling pathway implicated in the control of organ size also functions in the regulation of mitochondria in Drosophila as well as human cells. In Drosophila, activation of Yorkie causes direct transcriptional up-regulation of genes that regulate mitochondrial fusion, such as opa1-like (opa1) and mitochondria assembly regulatory factor (Marf), and results in fused mitochondria with dramatic reduction in reactive oxygen species (ROS) levels. When mitochondrial fusion is genetically attenuated, the Yorkie-induced cell proliferation and tissue overgrowth are significantly suppressed. The function of Yorkie is conserved across evolution, as activation of YAP2 in human cell lines causes increased mitochondrial fusion. Thus, mitochondrial fusion is an essential and direct target of the Yorkie/YAP pathway in the regulation of organ size control during development and could play a similar role in the genesis of cancer.

[Quality criteria for health promotion and primary prevention measures in association with obesity in children and adolescents. A BZgA-coordinated expert consensus]

On behalf of the Federal Ministry of Health, a working group coordinated by the Federal Center for Health Education (BZgA) compiled quality criteria for health promotion and primary prevention measures in association with obesity in children and adolescents that are applicable both to population-wide and to target group-specific measures. The criteria are intended to support the planning of new measures and the conceptual improvement of existing measures. Additional elements are the assessment of programs for financing purposes and the rendering of accounts to funding agencies, as well as the acquisition of further knowledge. The criteria, thus, address not only project developers and providers, but also multipliers who implement measures, as well as funding agencies, who can use the criteria as a basis for assessing the measures. The structure of the quality criteria is geared to the fundamental structure of the Public Health Action Cycle. In addition, resource orientation, participation and, above all, organizational development are important aspects associated with quality that have not been given adequate consideration to date. The quality criteria are applicable to all situation-based and behavioral prevention measures, and also development processes that focus on promoting the health and normal weight development of children and adolescents.

Utilization and Perceived Benefit for Diverse Users of Communities of Practice in a Healthcare Organization

Communities of practice have been heralded as a powerful knowledge management tool, especially for geographically disparate workgroups. Research into knowledge management (KM) in healthcare organizations is a needed research focus, given that differences exist in knowledge and knowledge management processes between healthcare and other organization types. The research presented in this paper examines the effectiveness of communities of practice as a knowledge sharing tool in a large and geographically disparate healthcare organization. Findings suggest that job role affects community members’ perceptions of the benefit and impact of communities of practice as well as their participation in such communities.

Group decisions and individual differences: route fidelity predicts flight leadership in homing pigeons (Columba livia)

How social-living animals make collective decisions is currently the subject of intense scientific interest, with increasing focus on the role of individual variation within the group. Previously, we demonstrated that during paired flight in homing pigeons, a fully transitive leadership hierarchy emerges as birds are forced to choose between their own and their partner's habitual routes. This stable hierarchy suggests a role for individual differences mediating leadership decisions within homing pigeon pairs. What these differences are, however, has remained elusive. Using novel quantitative techniques to analyse habitual route structure, we show here that leadership can be predicted from prior route-following fidelity. Birds that are more faithful to their own route when homing alone are more likely to emerge as leaders when homing socially. We discuss how this fidelity may relate to the leadership phenomenon, and propose that leadership may emerge from the interplay between individual route confidence and the dynamics of paired flight.

Dissecting the functional specificities of two Hox proteins

Hox proteins frequently select and regulate their specific target genes with the help of cofactors like Extradenticle (Exd) and Homothorax (Hth). For the Drosophila Hox protein Sex combs reduced (Scr), Exd has been shown to position a normally unstructured portion of Scr so that two basic amino acid side chains can insert into the minor groove of an Scr-specific DNA-binding site. Here we provide evidence that another Drosophila Hox protein, Deformed (Dfd), uses a very similar mechanism to achieve specificity in vivo, thus generalizing this mechanism. Furthermore, we show that subtle differences in the way Dfd and Scr recognize their specific binding sites, in conjunction with non-DNA-binding domains, influence whether the target gene is transcriptionally activated or repressed. These results suggest that the interaction between these DNA-binding proteins and the DNA-binding site determines the architecture of the Hox-cofactor-DNA ternary complex, which in turn determines whether the complex recruits coactivators or corepressors.

Objectively identifying landmark use and predicting flight trajectories of the homing pigeon using Gaussian processes

Pigeons home along idiosyncratic habitual routes from familiar locations. It has been suggested that memorized visual landmarks underpin this route learning. However, the inability to experimentally alter the landscape on large scales has hindered the discovery of the particular features to which birds attend. Here, we present a method for objectively classifying the most informative regions of animal paths. We apply this method to flight trajectories from homing pigeons to identify probable locations of salient visual landmarks. We construct and apply a Gaussian process model of flight trajectory generation for pigeons trained to home from specific release sites. The model shows increasing predictive power as the birds become familiar with the sites, mirroring the animal's learning process. We subsequently find that the most informative elements of the flight trajectories coincide with landscape features that have previously been suggested as important components of the homing task.