MRI morphometry of the anterior and posterior cerebellar vermis and its relationship to sensorimotor and cognitive functions in children.

INTRODUCTION: The human cerebellum emerges as a posterior brain structure integrating neural networks for sensorimotor, cognitive, and emotional processing across the lifespan. Developmental studies of the cerebellar anatomy and function are scant. We examine age-dependent MRI morphometry of the anterior cerebellar vermis, lobules I-V and posterior neocortical lobules VI-VII and their relationship to sensorimotor and cognitive functions. METHODS: Typically developing children (TDC; n=38; age 9-15) and healthy adults (HAC; n=31; 18-40) participated in high-resolution MRI. Rigorous anatomically informed morphometry of the vermis lobules I-V and VI-VII and total brain volume (TBV) employed manual segmentation computer-assisted FreeSurfer Image Analysis Program [http://surfer.nmr.mgh.harvard.edu]. The neuropsychological scores (WASI-II) were normalized and related to volumes of anterior, posterior vermis, and TBV. RESULTS: TBVs were age independent. Volumes of I-V and VI-VII were significantly reduced in TDC. The ratio of VI-VII to I-V (∼60%) was stable across age-groups; I-V correlated with visual-spatial-motor skills; VI-VII with verbal, visual-abstract and FSIQ. CONCLUSIONS: In TDC neither anterior I-V nor posterior VI-VII vermis attained adult volumes. The "inverted U" developmental trajectory of gray matter peaking in adolescence does not explain this finding. The hypothesis of protracted development of oligodendrocyte/myelination is suggested as a contributor to TDC's lower cerebellar vermis volumes.

An Ex-Vivo Study Comparing the Accuracy of the E-Connect S+ and Morita Tri Auto ZX2+ Endodontic Handpieces in Root Canal Length Determination.

INTRODUCTION: This ex vivo study evaluated the accuracy of the Electronic Apex Locator (EAL) and Automatic Apical Stop (AAS) functions of the E-Connect S+ and Morita Tri Auto ZX2+ cordless apex locators in determining patency length. METHODS: Sixty-four human teeth with a single root were randomly allocated into E-connect or Morita groups (n = 32). The canals were accessed and preflared, after which a size 15 K-file was inserted into the canal to the major foramen and recorded as the actual length (AL). Matched measurements were taken using the AAS and EAL functions and visually confirmed with confocal microscopy. The variance between canal length (mm), the persons correlation (ρ) between function and AL, and the accuracy (%) of the canal length relative to the AL (Δmm) between devices and functions were assessed. RESULTS: Regardless of device or function, all measurements were within 1±Δmm and correlated strongly (ρ > 0.97) with the AL. When considering a more stringent clinically acceptable range of 0.5±Δmm from the AL, all devices and functions demonstrated similar accuracy levels (84%-94%). However, at lower tolerance ranges, the E-connect device with the EAL function exhibited the highest accuracy. On average, all devices and functions stopped short of the AL (mean Δmm>0). CONCLUSION: The E-Connect S+ and Morita Tri Auto ZX2+ apex locators provided reliable accuracy in determining the position of the major foramen. These findings demonstrate a high level of reproducibility in canal length measurements using both cordless endodontic handpieces, regardless of whether the EAL or AAS functions were employed.

Pathologic classification of a late-onset peripheral neuropathy in a spontaneous Labrador retriever dog model.

Late-onset peripheral neuropathy (LPN) is a heritable canine neuropathy commonly found in Labrador retrievers and is characterized by laryngeal paralysis and pelvic limb paresis. Our objective was to establish canine LPN as a model for human hereditary peripheral neuropathy by classifying it as either an axonopathy or myelinopathy and evaluating length-dependent degeneration. We conducted a motor nerve conduction study of the sciatic and ulnar nerves, electromyography (EMG) of appendicular and epaxial musculature, and histologic analysis of sciatic and recurrent laryngeal nerves in LPN-affected and control dogs. LPN-affected dogs exhibited significant decreases in compound muscle action potential (CMAP) amplitude, CMAP area, and pelvic limb latencies. However, no differences were found in motor nerve conduction velocity, residual latencies, or CMAP duration. Distal limb musculature showed greater EMG changes in LPN-affected dogs. Histologically, LPN-affected dogs exhibited a reduction in the number of large-diameter axons, especially in distal nerve regions. In conclusion, LPN in Labrador retrievers is a common, spontaneous, length-dependent peripheral axonopathy that is a novel animal model of age-related peripheral neuropathy that could be used for fundamental research and clinical trials.

Service-learning outreach to attract high school students to degrees and careers in agricultural sciences.

Given projected deficits and a lack of diversity, there is a critical need to recruit and develop the next generation of the agricultural workforce. The objectives of our study were to evaluate if AgCamp, a one day workshop focused on agriculture delivered through a college student-led service-learning platform: (1) increased high school students' knowledge of agriculture, (2) changed their interests in pursuing degrees and careers in agriculture, and (3) increased their comfort and confidence in communicating with others in agriculture. We hosted high school students at AgCamp and provided them with instruction in animal science, horticulture, and agricultural mechanics. Pre- and post-test survey instruments were developed and distributed at the beginning and end of AgCamp. Data were analyzed with SPSS 26.0 using paired sample t-tests. As a result of attending this outreach initiative, high school students (n = 26) reported having more knowledge of horticulture (P < 0.01) and agricultural mechanics (P < 0.01), but not animal science (P = 0.12), likely due to greater incoming knowledge of this sub-discipline, as reflected on the pre-test value. High school participants were also more interested in pursuing a college degree (P = 0.04) and career (P < 0.01) in agriculture and became more confident approaching other high school students (P < 0.01), college students (P < 0.01), and college faculty (P = 0.01) involved in agriculture. Ultimately, participating in AgCamp stimulated high school students' knowledge and interest in pursuing agricultural degrees and careers, indicating there is value in offering youth outreach as short-term programming to attract students to agriculture.

Neurofilament light chain concentration does not correlate with disease status in Labrador Retrievers affected with idiopathic laryngeal paralysis.

OBJECTIVE: The aim of this study was to investigate whether plasma neurofilament light chain (pNfL) concentration was altered in Labrador Retrievers with idiopathic laryngeal paralysis (ILP) compared to a control population. A secondary aim was to investigate relationships between age, height, weight, and body mass index in the populations studied. ANIMALS: 123 dogs: 62 purebred Labrador Retrievers with ILP (ILP Cases) and 61 age-matched healthy medium- to large-breed dogs (Controls). METHODS: Dogs, recruited from August 1, 2016, to March 1, 2022, were categorized as case or control based on a combination of physical exam, neurologic exam, and history. Blood plasma was collected, and pNfL concentration was measured. pNfL concentrations were compared between ILP Cases and Controls. Covariables including age, height, and weight were collected. Relationships between pNfL and covariables were analyzed within and between groups. In dogs where 2 plasma samples were available from differing time points, pNfL concentrations were measured to evaluate alterations over time. RESULTS: No significant difference in pNfL concentration was found between ILP Cases and Control (P = .36). pNfL concentrations had moderate negative correlations with weight and height in the Control group; other variables did not correlate with pNfL concentrations in ILP Case or Control groups. pNfL concentrations do not correlate with ILP disease status or duration in Labrador Retrievers. CLINICAL RELEVANCE: There is no evidence that pNfL levels are altered due to ILP disease duration or progression when compared with healthy controls. When evaluating pNfL concentrations in the dog, weight and height should be considered.

Leukotriene B4 receptor 2 governs macrophage migration during tissue inflammation.

Chronic inflammation is the underlying cause of many diseases, including type 1 diabetes, obesity, and non-alcoholic fatty liver disease. Macrophages are continuously recruited to tissues during chronic inflammation where they exacerbate or resolve the pro-inflammatory environment. Although leukotriene B4 receptor 2 (BLT2) has been characterized as a low affinity receptor to several key eicosanoids and chemoattractants, its precise roles in the setting of inflammation and macrophage function remain incompletely understood. Here we used zebrafish and mouse models to probe the role of BLT2 in macrophage function during inflammation. We detected BLT2 expression in bone marrow derived and peritoneal macrophages of mouse models. Transcriptomic analysis of Ltb4r2-/- and WT macrophages suggested a role for BLT2 in macrophage migration, and studies in vitro confirmed that whereas BLT2 does not mediate macrophage polarization, it is required for chemotactic function, possibly mediated by downstream genes Ccl5 and Lgals3. Using a zebrafish model of tailfin injury, we demonstrated that antisense morpholino-mediated knockdown of blt2a or chemical inhibition of BLT2 signaling impairs macrophage migration. We further replicated these findings in zebrafish models of islet injury and liver inflammation. Moreover, we established the applicability of our zebrafish findings to mammals by showing that macrophages of Ltb4r2-/- mice have defective migration during lipopolysaccharide stimulation in vivo. Collectively, our results demonstrate that BLT2 mediates macrophage migration during inflammation, which implicates it as a potential therapeutic target for inflammatory pathologies.

Dissociable default-mode subnetworks subserve childhood attention and cognitive flexibility: Evidence from deep learning and stereotactic electroencephalography.

Cognitive flexibility encompasses the ability to efficiently shift focus and forms a critical component of goal-directed attention. The neural substrates of this process are incompletely understood in part due to difficulties in sampling the involved circuitry. We leverage stereotactic intracranial recordings to directly resolve local-field potentials from otherwise inaccessible structures to study moment-to-moment attentional activity in children with epilepsy performing a flexible attentional task. On an individual subject level, we employed deep learning to decode neural features predictive of task performance indexed by single-trial reaction time. These models were subsequently aggregated across participants to identify predictive brain regions based on AAL atlas and FIND functional network parcellations. Through this approach, we show that fluctuations in beta (12-30 Hz) and gamma (30-80 Hz) power reflective of increased top-down attentional control and local neuronal processing within relevant large-scale networks can accurately predict single-trial task performance. We next performed connectomic profiling of these highly predictive nodes to examine task-related engagement of distributed functional networks, revealing exclusive recruitment of the dorsal default mode network during shifts in attention. The identification of distinct substreams within the default mode system supports a key role for this network in cognitive flexibility and attention in children. Furthermore, convergence of our results onto consistent functional networks despite significant inter-subject variability in electrode implantations supports a broader role for deep learning applied to intracranial electrodes in the study of human attention.

Triplication of the interferon receptor locus contributes to hallmarks of Down syndrome in a mouse model.

Down syndrome (DS), the genetic condition caused by trisomy 21, is characterized by variable cognitive impairment, immune dysregulation, dysmorphogenesis and increased prevalence of diverse co-occurring conditions. The mechanisms by which trisomy 21 causes these effects remain largely unknown. We demonstrate that triplication of the interferon receptor (IFNR) gene cluster on chromosome 21 is necessary for multiple phenotypes in a mouse model of DS. Whole-blood transcriptome analysis demonstrated that IFNR overexpression associates with chronic interferon hyperactivity and inflammation in people with DS. To define the contribution of this locus to DS phenotypes, we used genome editing to correct its copy number in a mouse model of DS, which normalized antiviral responses, prevented heart malformations, ameliorated developmental delays, improved cognition and attenuated craniofacial anomalies. Triplication of the Ifnr locus modulates hallmarks of DS in mice, suggesting that trisomy 21 elicits an interferonopathy potentially amenable to therapeutic intervention.

The impact of COVID-19 on primary care accessibility and the role of telehealth for patients with chronic conditions.

Objectives: The objective of this study is to quantify how long patients took to complete their rescheduled primary care appointment pre-pandemic (2019) and during an initial pandemic period (2020). In doing so, the study evaluates telehealth's role in helping primary care patients - particularly in patients with chronic conditions - withstand COVID's significant disruption in care. Methods: Cancelled and completed primary care appointments for adult patients were extracted from the beginning of the pandemic (March 1 to July 31, 2020) and a similar period pre-pandemic (March 1 to July 31, 2019). Days to the subsequent completed visit after cancellation (through June 30, 2021) and appointment modality (in-person, phone, video) were examined. Statistical testing was done to determine statistical significance, and a linear regression was run to control for effects of other study variables. Results: Pre-pandemic patients with chronic conditions needed 52.3 days on average to reschedule their cancelled in-person appointment. During the early pandemic period, chronic condition patients who saw their provider in-person took on average 78.8 days. During the same pre-pandemic period, patients with chronic conditions had their average wait time decrease to 51.5 days when rescheduling via telehealth. These differences were similar for patients without chronic conditions. Conclusions: This analysis shows that telehealth created return to care timelines comparable to the pre-pandemic period which is especially important for patients with chronic conditions. Public interest summary: Telehealth visits (i.e., talking with a physician via phone or video call) help patients continue to receive the medical care they need - especially during disruptive periods such as the COVID pandemic. Access to telehealth is the strongest predictor in determining how soon a patient will complete their reschedule primary care appointment. Because telehealth is so important, health care providers and systems need to continue to offer patients the ability to talk with their physician via phone or video call.

Non-Alcoholic Fatty Liver Disease: Translating Disease Mechanisms into Therapeutics Using Animal Models.

Nonalcoholic fatty liver disease (NAFLD) is a range of pathologies arising from fat accumulation in the liver in the absence of excess alcohol use or other causes of liver disease. Its complications include cirrhosis and liver failure, hepatocellular carcinoma, and eventual death. NAFLD is the most common cause of liver disease globally and is estimated to affect nearly one-third of individuals in the United States. Despite knowledge that the incidence and prevalence of NAFLD are increasing, the pathophysiology of the disease and its progression to cirrhosis remain insufficiently understood. The molecular pathogenesis of NAFLD involves insulin resistance, inflammation, oxidative stress, and endoplasmic reticulum stress. Better insight into these molecular pathways would allow for therapies that target specific stages of NAFLD. Preclinical animal models have aided in defining these mechanisms and have served as platforms for screening and testing of potential therapeutic approaches. In this review, we will discuss the cellular and molecular mechanisms thought to contribute to NAFLD, with a focus on the role of animal models in elucidating these mechanisms and in developing therapies.

The lifesaving effects of cardiac adhesions.

Patients that incur myocardial disruption from penetrating cardiac injuries have an average 6%-10% expectancy rate of reaching the hospital alive. If prompt recognition on arrival is not immediate, the morbidity and mortality are significantly higher due to the secondary physiologic sequalae of either cardiogenic or hemorrhagic shock. Even after a triumphant arrival at a medical facility, out of that 6%-10%, half of those patients are not expected to survive. The unique significance of the presenting case breaks this tradition, expanding past the paradigms and issuing an exceptional understanding of the protective effects that cardiac surgery can futuristically cause through preformed adhesions. In our case, the cardiac adhesions achieved this by containing a penetrating cardiac injury that had caused complete ventricular disruption.

SHARING Choices: Lessons Learned from a Primary-Care Focused Advance Care Planning Intervention.

BACKGROUND: Few advance care planning (ACP) interventions have been scaled in primary care. PROBLEM: Best practices for delivering ACP at scale in primary care do not exist and prior efforts have excluded older adults with Alzheimer's Disease and Related Dementias (ADRD). INTERVENTION: SHARING Choices (NCT#04819191) is a multicomponent cluster-randomized pragmatic trial conducted at 55 primary care practices from two care delivery systems in the Mid-Atlantic region of the U.S. We describe the process of implementing SHARING Choices within 19 practices randomized to the intervention, summarize fidelity to planned implementation, and discuss lessons learned. OUTCOMES: Embedding SHARING Choices involved engagement with organizational and clinic-level partners. Of 23,220 candidate patients, 17,931 outreach attempts by phone (77.9%) and the patient portal (22.1%) were made by ACP facilitators and 1215 conversations occurred. Most conversations (94.8%) were less than 45 minutes duration. Just 13.1% of ACP conversations included family. Patients with ADRD comprised a small proportion of patients who engaged in ACP. Implementation adaptations included transitioning to remote modalities, aligning ACP outreach with the Medicare Annual Wellness Visit, accommodating primary care practice flexibility. LESSONS LEARNED: Study findings reinforce the value of adaptable study design; co-designing workflow adaptations with practice staff; adapting implementation processes to fit the unique needs of two health systems; and modifying efforts to meet health system goals and priorities.

Traumatic aortic injury from pellet gun: A case report.

Acute traumatic aortic injuries are of the most lethal sequelae of penetrating thoracic injuries and require rapid detection and management. The American College of Radiology currently recommends the use of noncontrast CT, followed by computed tomography angiography (CTA) as the first-line imaging modalities when traumatic aortic injury is suspected. Direct signs of aortic injury on CTA include pseudoaneurysm, focal contour abnormality, intimal flap, intramural hematoma, an abrupt change in aortic caliber, and contrast extravasation. Aortic pseudoaneurysms are most often caused by blunt or penetrating trauma that results in damage to the vessel wall, turbulent blood flow, and formation of a surrounding hematoma contained by a wall of products from the clotting cascade. This wall is weaker than those of a true aneurysm and will ultimately rupture over time if not repaired. Traumatic aortic pseudoaneurysms are preferably treated by thoracic endovascular aortic repair using a prosthetic stent graft. Here, we present a 44-yearold female with a history of homelessness, polysubstance use disorder, and HIV who presented to the emergency department after being found down. She reported being shot by a pellet gun, and physical examination revealed a penetrating left-sided chest wound that appeared to be several days old. A STAT CTA was obtained and revealed a hemopneumothorax and possible thoracic aortic pseudoaneurysm. A left-sided chest tube was placed and the patient underwent thoracic endovascular aortic repair through right femoral arterial access and tolerated the procedure well. The patient was placed on daily aspirin postoperatively and discharged on post-op day 5.

Is the Grass Really Greener? The Influence of Gender Identity and Sexual Orientation on Mate Copying Behaviors.

Mate copying is a sexual strategy whereby individuals attend to socially available information about their prospective mate. This allows for more accurate decision making in regard to mating. This phenomenon was originally demonstrated among nonhumans, but there is an increasing weight of evidence suggesting that humans also engage in mate copying. Research typically focuses on heterosexual cisgender women, with no previous studies having looked at those identifying outside of the traditional gender binary. The current study aimed to address this gap by examining the impact of gender identity and sexual orientation on the propensity to engage in mate copying. Participants (N = 831) completed an online survey providing desirability ratings for photographs alone (T1) and then rated the same photographs after receiving social information about the relationship status and previous relationship history of the pictured individual (T2). It was found that both gender identity (F(4, 713) = 3.94, ηp2 = .02) and sexual orientation (F(4, 713) = 4.40, ηp2 = .02) influenced an individual's overall propensity to mate copy, and that desirability patterns for individuals were very different depending on these variables. It was concluded that while mate copying certainly is evident among humans, the phenomenon is extremely nuanced and sensitive.

Effect of Sexual Racism on Partner Desirability in Gay Asian Men.

Sexual racism-including or excluding racial minority members in partner selection based on race-negatively affects Asian men who have sex with men (MSM) across various domains. The current study aims to investigate the effect of potential partners' racial preferences on desirability in Asian MSM. The relationship between sexual racism awareness and partner desirability when evaluating white partners with racial preferences was also investigated. A sample of Asian MSM (N = 128) responded to hypothetical online dating scenarios in which the racial background (Asian/white) and racial preference (none/Asian/white) of facial stimuli were manipulated. A two-way ANOVA with post-hoc Bonferroni analyses confirmed that, as hypothesized, among potential white partners, those that exhibited no racial preferences were most desirable, F(1.66, 210.54) = .11.37, p < .001, ηp2 = .08. Among potential Asian partners, those that preferred white men were least desirable, F(1.82, 231.60) = 81.95, p < .001, ηp2 = .39. Unexpectedly, there was no relationship evident between sexual racism awareness and desirability for potential white partners (in any racial preference condition; all rs < .20). Our findings suggest that overt expression of certain racial preferences can negatively affect desirability in online dating applications.

A Tet-Inducible CRISPR Platform for High-Fidelity Editing of Human Pluripotent Stem Cells.

Pluripotent stem cells (PSCs) offer an exciting resource for probing human biology; however, gene-editing efficiency remains relatively low in many cell types, including stem cells. Gene-editing using the CRISPR-Cas9 system offers an attractive solution that improves upon previous gene-editing approaches; however, like other technologies, off-target mutagenesis remains a concern. High-fidelity Cas9 variants greatly reduce off-target mutagenesis and offer a solution to this problem. To evaluate their utility as part of a cell-based gene-editing platform, human PSC lines were generated with a high-fidelity (HF) tetracycline-inducible engineered Streptococcus pyogenes SpCas9 (HF-iCas9) integrated into the AAVS1 safe harbor locus. By engineering cells with controllable expression of Cas9, we eliminated the need to include a large Cas9-expressing plasmid during cell transfection. Delivery of genetic cargo was further optimized by packaging DNA targeting guide RNAs (gRNAs) and donor fragments into a single plasmid backbone. The potential of homology-directed repair (HDR) based gene knock-in at the CLYBL safe harbor site and endogenous SOX2 and SIX6 genes were demonstrated. Moreover, we used non-homologous end-joining (NHEJ) for gene knockout of disease-relevant alleles. These high-fidelity CRISPR tools and the resulting HF-iCas9 cell lines will facilitate the production of cell-type reporters and mutants across different genetic backgrounds.

Cardiac Screening and Disease Characteristics of Patients with Ocular Sarcoidosis.

PURPOSE: This is a retrospective nonrandomized cohort study investigating the prevalence, timing, and type of cardiac sarcoidosis indications on electrocardiogram in patients with diagnosed or suspected ocular sarcoidosis. METHODS: Medical histories of individuals seen from 2005 to 2020 at two centers with diagnosed or suspected ocular sarcoidosis were searched, and statistical methods were used to evaluate the relevance of each aspect obtained. RESULTS: Approximately 16% of the individuals in our cohort showed signs of cardiac sarcoidosis on ECG, primarily bundle branch blocks, and premature ventricular contractions, close to the time of their initial ocular sarcoidosis documentation. Males exhibited higher rates of clinically significant extra-pulmonary sarcoidosis. No other demographic differences were found. CONCLUSIONS: Our findings highlight the importance for further differentiation of non-infectious sarcoidosis and the utility of electrocardiogram screening. Studies with larger cohorts of ocular sarcoidosis might be needed to elucidate demographic differences within this patient population.

Green edge emitting lasers with porous GaN cladding.

GaN lasers with green emission wavelength at λ = 510 nm have been fabricated using novel nano-porous GaN cladding under pulsed electrical injection. The low slope efficiency of 0.13 W/A and high threshold current density of 14 kA/cm2 are related to a combination of poor injection efficiency and high loss, analyzed by the independent characterization methods of variable stripe length and segmented contacts. Continuous wave operation showed narrowed spectra and augmented spontaneous emission.

Association of Baseline Frailty Status and Age With Postoperative Complications After Cochlear Implantation: A National Inpatient Sample Study.

OBJECTIVE: To conduct a national registry-based evaluation of the independent associations of chronological age and frailty, as measured by 5- and 11-factor modified frailty index (mFI-5, mFI-11) score, on postoperative outcomes of participants undergoing cochlear implantation (CI). STUDY DESIGN: Cross-sectional analysis. SETTING: Multicenter national database. PARTICIPANTS: Adults 18 years or older who underwent CI during 2001 to 2018. MAIN OUTCOME MEASURES: Any postoperative complications (determined as the presence of major, minor, or implant-specific), extended hospital length of stay (eLOS) (≥75th percentile of study population), and nonhome discharge destination. RESULTS: There were 5,130 participants included with a median age of 60 years (interquartile range, 44-73 y) and slight female predominance (53.5%). Under mFI-5 scoring, there were 2,979 (58.1%) robust (mFI-5 = 0), 1710 (33.3%) prefrail (mFI-5 = 1), 362 (7.1%) frail (mFI-5 = 2), and 78 (1.5%) severely frail (mFI-5 ≥ 3) participants. Three hundred twenty-eight (6.49%) participants experienced a postoperative complication, with 320 (6.2%) discharged to a nonhome destination. Multivariate analysis showed no statistically significant correlation between increasing participant age or frailty status and postoperative complications; however, increasing baseline frailty tier showed an independent association with risk of eLOS (severely frail: odds ratio, 4..83; 95% confidence interval, 3.00-7.75; p < 0.001) and nonhome discharge (severely frail: odds ratio, 6.51; 95% confidence interval, 3.81-11.11; p < 0.001). The mFI-11 showed very similar trends. CONCLUSION: Among those evaluated, this study demonstrates that CI is a low-risk procedure in participants of all ages. Increasing frailty does not predispose to postoperative complications. However, frail patients are at additional risk for an eLOS and nonhome discharge. Short follow-up time, hospital-coding errors, and selection bias of more robust patients may limit the true results of this study.

Compositionally and density stratified igneous terrain in Jezero crater, Mars.

Before Perseverance, Jezero crater's floor was variably hypothesized to have a lacustrine, lava, volcanic airfall, or aeolian origin. SuperCam observations in the first 286 Mars days on Mars revealed a volcanic and intrusive terrain with compositional and density stratification. The dominant lithology along the traverse is basaltic, with plagioclase enrichment in stratigraphically higher locations. Stratigraphically lower, layered rocks are richer in normative pyroxene. The lowest observed unit has the highest inferred density and is olivine-rich with coarse (1.5 millimeters) euhedral, relatively unweathered grains, suggesting a cumulate origin. This is the first martian cumulate and shows similarities to martian meteorites, which also express olivine disequilibrium. Alteration materials including carbonates, sulfates, perchlorates, hydrated silicates, and iron oxides are pervasive but low in abundance, suggesting relatively brief lacustrine conditions. Orbital observations link the Jezero floor lithology to the broader Nili-Syrtis region, suggesting that density-driven compositional stratification is a regional characteristic.