Developing a hippocampal neural prosthetic to facilitate human memory encoding and recall of stimulus features and categories.

Objective: Here, we demonstrate the first successful use of static neural stimulation patterns for specific information content. These static patterns were derived by a model that was applied to a subject's own hippocampal spatiotemporal neural codes for memory. Approach: We constructed a new model of processes by which the hippocampus encodes specific memory items via spatiotemporal firing of neural ensembles that underlie the successful encoding of targeted content into short-term memory. A memory decoding model (MDM) of hippocampal CA3 and CA1 neural firing was computed which derives a stimulation pattern for CA1 and CA3 neurons to be applied during the encoding (sample) phase of a delayed match-to-sample (DMS) human short-term memory task. Main results: MDM electrical stimulation delivered to the CA1 and CA3 locations in the hippocampus during the sample phase of DMS trials facilitated memory of images from the DMS task during a delayed recognition (DR) task that also included control images that were not from the DMS task. Across all subjects, the stimulated trials exhibited significant changes in performance in 22.4% of patient and category combinations. Changes in performance were a combination of both increased memory performance and decreased memory performance, with increases in performance occurring at almost 2 to 1 relative to decreases in performance. Across patients with impaired memory that received bilateral stimulation, significant changes in over 37.9% of patient and category combinations was seen with the changes in memory performance show a ratio of increased to decreased performance of over 4 to 1. Modification of memory performance was dependent on whether memory function was intact or impaired, and if stimulation was applied bilaterally or unilaterally, with nearly all increase in performance seen in subjects with impaired memory receiving bilateral stimulation. Significance: These results demonstrate that memory encoding in patients with impaired memory function can be facilitated for specific memory content, which offers a stimulation method for a future implantable neural prosthetic to improve human memory.

Socio-demographic profile of medical students in Aotearoa, New Zealand (2016-2020): a nationwide cross-sectional study.

OBJECTIVE: To determine the socio-demographic profile of all students enrolled to study medicine in Aotearoa New Zealand (NZ). DESIGN AND SETTING: Observational, cross-sectional study. Data were sought from the Universities of Auckland and Otago, the two NZ tertiary education institutions providing medical education, for the period 2016-2020 inclusive. These data are a subset of the larger project 'Mirror on Society' examining all regulated health professional enrolled students in NZ. VARIABLES OF INTEREST: gender, citizenship, ethnicity, rural classification, socioeconomic deprivation, school type and school socioeconomic scores. NZ denominator population data (18-29 years) were sourced from the 2018 census. PARTICIPANTS: 2858 students were enrolled to study medicine between 2016 and 2020 inclusive. RESULTS: There were more women (59.1%) enrolled to study medicine than men (40.9%) and the majority (96.5%) were in the 18-29 years age range. Maori students (rate ratio 0.92; 95% CI 0.84 to 1.0) and Pacific students (rate ratio 0.85; 95% CI 0.73 to 0.98) had lower overall rates of enrolment. For all ethnic groups, irrespective of rural or urban origin, enrolment rates had a nearly log-linear negative relationship with increasing socioeconomic deprivation. Enrolments were lower for students from rural areas compared with those from urban areas (rate ratio 0.53; 95% CI 0.46-0.61). Overall NZ's medical students do not reflect the diverse communities they will serve, with under-representation of Maori and Pacific students and students who come from low socioeconomic and rural backgrounds. CONCLUSIONS: To meaningfully address these issues, we suggest the following policy changes: universities commit and act to Indigenise institutional ways of knowing and being; selection policies are reviewed to ensure that communities in greatest need of doctors are prioritised for enrolment into medicine (specifically, the impact of low socioeconomic status should be factored into selection decisions); and the government fund more New Zealanders to study medicine.

Cultural and translation challenges in assessing health literacy among immigrants from the former Soviet Union.

Health literacy is an important foundation for health promotion and an under-recognized risk factor for immigrant and refugee groups. Yet measuring health literacy among diverse ethnic and linguistic populations presents complex challenges. We describe cultural and translation challenges encountered in measuring health literacy among Russian-speaking immigrants to the USA and offer a mixed-methods approach to understanding them. The Rx-Health Literacy (RxHL) study used cross-sectional quantitative and qualitative data to examine health literacy and medication adherence among five cultural and four language groups (Latinx, Vietnamese, African-American, Russian-speaking immigrant and White American) who are patients at Caring Health Center, a federally qualified health center in Springfield, MA. We translated an existing health literacy scale into Russian and Vietnamese and examined item difficulty across cultural groups. We conducted qualitative cognitive interviews to learn more about Russian speakers' understandings of the scale. Health literacy scores varied by cultural group, and the range of correct responses was much greater among Russian speakers than in other groups. Percentage correct varied by 69.7% for Russian speakers, compared with 25.0-44.0% for other groups. These findings indicate greater variability in health literacy levels among this group compared with others. Cognitive interviews with Russian-speaking participants revealed multiple interpretations of several items, suggesting that the English version of the scale contained embedded meanings associated with an American health care context that were not captured in the translated instrument. Combining qualitative and quantitative research methods allows for greater insight into contextual and translation factors that may shape the results of translated instruments in unanticipated ways.

Suppression of cortical electrostimulation artifacts using pre-whitening and null projection.

Objective.Invasive brain-computer interfaces (BCIs) have shown promise in restoring motor function to those paralyzed by neurological injuries. These systems also have the ability to restore sensation via cortical electrostimulation. Cortical stimulation produces strong artifacts that can obscure neural signals or saturate recording amplifiers. While front-end hardware techniques can alleviate this problem, residual artifacts generally persist and must be suppressed by back-end methods.Approach.We have developed a technique based on pre-whitening and null projection (PWNP) and tested its ability to suppress stimulation artifacts in electroencephalogram (EEG), electrocorticogram (ECoG) and microelectrode array (MEA) signals from five human subjects.Main results.In EEG signals contaminated by narrow-band stimulation artifacts, the PWNP method achieved average artifact suppression between 32 and 34 dB, as measured by an increase in signal-to-interference ratio. In ECoG and MEA signals contaminated by broadband stimulation artifacts, our method suppressed artifacts by 78%-80% and 85%, respectively, as measured by a reduction in interference index. When compared to independent component analysis, which is considered the state-of-the-art technique for artifact suppression, our method achieved superior results, while being significantly easier to implement.Significance.PWNP can potentially act as an efficient method of artifact suppression to enable simultaneous stimulation and recording in bi-directional BCIs to biomimetically restore motor function.

A comprehensive description of kidney disease progression after acute kidney injury from a prospective, parallel-group cohort study.

Acute kidney injury (AKI) is associated with adverse long-term outcomes, but many studies are retrospective, focused on specific patient groups or lack adequate comparators. The ARID (AKI Risk in Derby) Study was a five-year prospective parallel-group cohort study to examine this. Hospitalized cohorts with and without exposure to AKI were matched 1:1 for age, baseline kidney function, and diabetes. Estimated glomerular filtration rate (eGFR) and the urinary albumin:creatinine ratio (uACR) were measured at three-months, one-, three- and five-years. Outcomes included kidney disease progression, heart failure episodes and mortality. In 866 matched individuals, kidney disease progression at five years was found to be significantly increased in 30% of the exposed group versus 7% of those non-exposed (adjusted odds ratio 2.49 [95% confidence interval 1.43 to 4.36]). In the AKI group, this was largely characterized by incomplete recovery of kidney function by three months. Further episodes of AKI during follow-up were significantly more common in the exposed group (odds ratio 2.71 [1.94 to 3.77]) and had an additive effect on risk of kidney disease progression. Mortality and heart failure episodes were more frequent in the exposed group, but the association with AKI was no longer significant when models were adjusted for three-month eGFR and uACR. In a general hospitalized population, kidney disease progression after five years was common and strongly associated with AKI. Thus, the time course of changes and the attenuation of associations with adverse outcomes after adjustment for three-month eGFR and uACR suggest non-recovery of kidney function is an important assessment in post-AKI care and a potential future target for intervention. STUDY REGISTRATION: ISRCTN25405995.

Exercise repetition rate measured with simple sensors at home can be used to estimate Upper Extremity Fugl-Meyer score after stroke.

Introduction: It would be valuable if home-based rehabilitation training technologies could automatically assess arm impairment after stroke. Here, we tested whether a simple measure-the repetition rate (or "rep rate") when performing specific exercises as measured with simple sensors-can be used to estimate Upper Extremity Fugl-Meyer (UEFM) score. Methods: 41 individuals with arm impairment after stroke performed 12 sensor-guided exercises under therapist supervision using a commercial sensor system comprised of two pucks that use force and motion sensing to measure the start and end of each exercise repetition. 14 of these participants then used the system at home for three weeks. Results: Using linear regression, UEFM score was well estimated using the rep rate of one forward-reaching exercise from the set of 12 exercises (r2 = 0.75); this exercise required participants to alternately tap pucks spaced about 20 cm apart (one proximal, one distal) on a table in front of them. UEFM score was even better predicted using an exponential model and forward-reaching rep rate (Leave One Out Cross Validation (LOOCV) r2 = 0.83). We also tested the ability of a nonlinear, multivariate model (a regression tree) to predict UEFM, but such a model did not improve prediction (LOOCV r2 = 0.72). However, the optimal decision tree also used the forward-reaching task along with a pinch grip task to subdivide more and less impaired patients in a way consistent with clinical intuition. At home, rep rate for the forward-reaching exercise well predicted UEFM score using an exponential model (LOOCV r2 = 0.69), but only after we re-estimated coefficients using the home data. Discussion: These results show how a simple measure-exercise rep rate measured with simple sensors-can be used to infer an arm impairment score and suggest that prediction models should be tuned separately for the clinic and home environments.

Alternative and legacy flame retardants in marine mammals from three northern ocean regions.

Flame retardants are globally distributed contaminants that have been linked to negative health effects in humans and wildlife. As top predators, marine mammals bioaccumulate flame retardants and other contaminants in their tissues which is one of many human-imposed factors threatening population health. While some flame retardants, such as the polybrominated diphenyl ethers (PBDE), have been banned because of known toxicity and environmental persistence, limited data exist on the presence and distribution of current-use alternative flame retardants in marine mammals from many industrialized and remote regions of the world. Therefore, this study measured 44 legacy and alternative flame retardants in nine marine mammal species from three ocean regions: the Northwest Atlantic, the Arctic, and the Baltic allowing for regional, species, age, body condition, temporal, and tissue comparisons to help understand global patterns. PBDE concentrations were 100-1000 times higher than the alternative brominated flame retardants (altBFRs) and Dechloranes. 2,2',4,5,5'-pentabromobiphenyl (BB-101) and hexabromobenzene (HBBZ) were the predominant altBFRs, while Dechlorane-602 was the predominant Dechlorane. This manuscript also reports only the second detection of hexachlorocyclopentadienyl-dibromocyclooctane (HCDBCO) in marine mammals. The NW Atlantic had the highest PBDE concentrations followed by the Baltic and Arctic which reflects greater historical use of PBDEs in North America compared to Europe and greater industrialization of North America and Baltic countries compared to the Arctic. Regional patterns for other compounds were more complicated, and there were significant interactions among species, regions, body condition and age class. Lipid-normalized PBDE concentrations in harbor seal liver and blubber were similar, but HBBZ and many Dechloranes had higher concentrations in liver, indicating factors other than lipid dynamics affect the distribution of these compounds. The health implications of contamination by this mixture of compounds are of concern and require further research.

Exposure to legacy and alternative flame retardants in two harbor seal populations and the association with blubber fatty acid profiles.

Flame retardants (FRs) are ubiquitously present in various environmental compartments due to widespread application. However, there have been few reports on the alternative FRs in harbor seals, and their relationship with fatty acid (FA) profiles have largely been overlooked. Here, we investigated the levels of legacy and alternative FRs and FA profiles in the blubber of harbor seals from the coasts of South Sweden (2009-2016) and Northeastern US (NE US) (1999-2010). We observed different proportions of mono- and poly-unsaturated FAs (MUFAs and PUFAs) between the two populations, which may reflect variations in the diet. Significantly higher concentrations of ΣPBDE were also observed in harbor seals from US compared to those from Sweden, both dominated by BDE 47. By comparison, the levels of alternative FRs, noticeably HBBZ and PBEB were much lower compared to those of PBDEs. Moreover, we found a positive correlation between BDE 99 and Σn-6/Σn-3 PUFA in harbor seals from Sweden. In addition, BDE 153 and BDE 154 were positively correlated with ΣUFA/ΣSFA in seals from Sweden and US, respectively. Our results imply the influence of diet in FA profiles and FR concentrations in top predators, as well as the importance of blubber FA characteristics in indicating FR exposure. Further investigations are required to assess the risk of exposure in these harbor seals, as well as to elucidate the underlying mechanisms associating FA profiles with FR exposure.

National cross-sectional study of the sociodemographic characteristics of Aotearoa New Zealand's regulated health workforce pre-registration students: a mirror on society?

OBJECTIVES: To provide a sociodemographic profile of students enrolled in their first year of a health professional pre-registration programme offered within New Zealand (NZ) tertiary institutions. DESIGN: Observational, cross-sectional study. Data were sought from NZ tertiary education institutions for all eligible students accepted into the first 'professional' year of a health professional programme for the 5-year period 2016-2020 inclusive. VARIABLES OF INTEREST: gender, citizenship, ethnicity, rural classification, socioeconomic deprivation, school type and school socioeconomic scores. Analyses were carried out using the R statistics software. SETTING: Aotearoa NZ. PARTICIPANTS: All students (domestic and international) accepted into the first 'professional' year of a health professional programme leading to registration under the Health Practitioners Competence Assurance Act 2003. RESULTS: NZ's health workforce pre-registration students do not reflect the diverse communities they will serve in several important dimensions. There is a systematic under-representation of students who identify as Maori and Pacific, and students who come from low socioeconomic and rural backgrounds. The enrolment rate for Maori students is about 99 per 100 000 eligible population and for some Pacific ethnic groups is lower still, compared with 152 per 100 000 for NZ European students. The unadjusted rate ratio for enrolment for both Maori students and Pacific students versus 'NZ European and Other' students is approximately 0.7. CONCLUSIONS: We recommend that: (1) there should be a nationally coordinated system for collecting and reporting on the sociodemographic characteristics of the health workforce pre-registration; (2) mechanisms be developed to allow the agencies that fund tertiary education to base their funding decisions directly on the projected health workforce needs of the health system and (3) tertiary education funding decisions be based on Te Tiriti o Waitangi (the foundational constitutional agreement between the Indigenous people, Maori and the British Crown signed in 1840) and have a strong pro-equity focus.

Effective and respectful interaction with Maori: How the regulators of health professionals are responding to the Health Practitioners Competence Assurance Amendment Act 2019.

AIMS: To ascertain the response of registered health professional regulators to the legislated requirement under the Health Practitioners Competence Assurance Amendment Act 2019 (HPCA Amendement Act) that practitioners are culturally competent and, specifically, enabling "effective and respectful interaction with Maori". METHOD: A document analysis of the extent to which the culturally competent requirement is indicated in information about professional competencies within publicly available information of the 17 responsible authorities (RAs) that govern health practitioners under the Health Practitioners Competence Assurance legislation. RESULTS: Three years after the amendment to the original Act (HPCA Act) requiring health professionals to be culturally competent specifically in relation to interacting with Maori, only four of the 17 RAs fully reference the amended requirement, and only two RAs link this specific cultural competence to the requirements of the amended Act (HPCA Amendment Act). The majority of the RAs have yet to integrate references to engaging with Maori in this way into their professional competencies. CONCLUSIONS: Culturally competent practice is only meaningful once it is enacted by individual practitioners in their interactions with others. It is imperative for RAs to include the cultural competence requirement into their published information about professional competencies as this would signal to the profession, practitioners, and wider community that effective and respectful interaction with Maori is a fundamental expectation of all health practitioners in this country. Other issues identified during the analysis suggest an emphasis on administration and bureaucracy. This presents an opportunity for consolidating the practice of RAs including how key functions are expressed and promulgated.

Optimized Home Rehabilitation Technology Reduces Upper Extremity Impairment Compared to a Conventional Home Exercise Program: A Randomized, Controlled, Single-Blind Trial in Subacute Stroke.

BACKGROUND: Upper extremity (UE) stroke rehabilitation requires patients to perform exercises at home, yet patients show limited benefit from paper-based home exercise programs. OBJECTIVE: To compare the effectiveness of 2 home exercise programs for reducing UE impairment: a paper-based approach and a sensorized exercise system that incorporates recommended design features for home rehabilitation technology. METHODS: In this single-blind, randomized controlled trial, 27 participants in the subacute phase of stroke were assigned to the sensorized exercise (n = 14) or conventional therapy group (n = 13), though 2 participants in the conventional therapy group were lost to follow-up. Participants were instructed to perform self-guided movement training at home for at least 3 hours/week for 3 consecutive weeks. The sensorized exercise group used FitMi, a computer game with 2 puck-like sensors that encourages movement intensity and auto-progresses users through 40 exercises. The conventional group used a paper book of exercises. The primary outcome measure was the change in Upper Extremity Fugl-Meyer (UEFM) score from baseline to follow-up. Secondary measures included the Modified Ashworth Scale for spasticity (MAS) and the Visual Analog Pain (VAP) scale. RESULTS: Participants who used FitMi improved by an average of 8.0 ± 4.6 points on the UEFM scale compared to 3.0 ± 6.1 points for the conventional participants, a significant difference (t-test, P = .029). FitMi participants exhibited no significant changes in UE MAS or VAP scores. CONCLUSIONS: A sensor-based exercise system incorporating a suite of recommended design features significantly and safely reduced UE impairment compared to a paper-based, home exercise program. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03503617.

Occurrence and tissue-specific partitioning of alternative brominated flame retardants in northwest Atlantic harbor seal pups (Phoca vitulina vitulina).

Brominated flame retardants such as polybrominated diphenyl ethers (PBDEs) have been used for decades until evidence of negative health effects led to bans in many countries. PBDEs have since been replaced by alternative legacy compounds or newly developed chemicals. In this study, eight alternative brominated flame retardants were analyzed in blubber and liver of harbor seal pups (≤6 months) from the Northwest Atlantic collected during 2001-2010 to elucidate concentrations, patterns, contamination trends, potential maternal transfer, and tissue partitioning. All compounds were detected in liver and blubber tissues with hexabromocyclododecane (HBCD) isomers and 2-ethylhexyl 2,3,4,5-tetrabromobenzoate (TBB) predominating. Overall, α-HBCD was the dominant HBCD isomer in both tissues although the concentrations of γ-HBCD exceeded those of α-HBCD in seven pups, indicating their mothers may have had alternative dietary patterns or recent exposure to the commercial mixture. Although it was detected in less than half of the samples, to our knowledge, this is the first study to report tetrabromobisphenol A (TBBPA) concentrations in multiple tissues of a top marine predator. For the brominated components of Firemaster® flame retardants, TBB concentrations exceeded bis-(2-ethylhexyl)-tetrabromophthalate (TBPH). This pattern may result from recent exposure to commercial mixtures in which TBB exceeds TBPH 4:1 or from differences in perinatal or lactational transfer efficiency of the two compounds. Between the two tissues, lipid-normalized ß-HBCD, γ-HBCD, TBB and decabromodiphenyl ethane (DBDPE) concentrations were significantly higher in liver than blubber. This indicates that the bioaccumulation of these chemicals is not simply related to lipid dynamics but may be linked to blood proteins. This study demonstrates that harbor seal pups from this region are contaminated with alternative flame retardants passed to them via placental or lactational transfer. Given the evidence for negative health effects of these chemicals, this contamination adds additional pressure on the first year survival of these young, developing animals.

Results of a 2-week novel robotic rehabilitation program in 18 children with prior hemispherectomy.

BACKGROUND: Partial preservation of sensory and motor functions in the contralateral extremities after hemispherectomy is likely secondary to cortical reorganization of the remaining hemisphere and can be improved by rehabilitation. This study aims to investigate behavioral changes that may occur after a 2-week novel robotic rehabilitation program in 18 children with prior anatomic hemispherectomy. Other conventional rehabilitation methods were also reviewed and compared. METHODS: This study examined the impact of a novel robotic rehabilitation 2-week program on 18 hemispherectomy patients (average age 14.3 ± 3.9 years; age at hemispherectomy 5.6 ± 4.5 years). RESULTS: Statistically significant improvements were seen in the six-minute walk test (29 m, p < 0.001), Canadian Occupational Performance Measure performance (1.64 points, p = 0.002) and satisfaction (2.49 points, p = 0.001), and individual perceived performance on survey (1.72 points, p = 0.042). Fifteen patients showed improvement in the upper extremity Fugl-Meyer scores with an average increase of 3 points (p = 0.006). CONCLUSION: This study demonstrates clinically meaningful and statistically significant improvements in motor function and behavior following a novel robotic rehabilitation two-week program.

Content Analysis of Patient-Facing Information Related to Preeclampsia.

BACKGROUND: Previous research has shown pregnant people are not knowledgeable about preeclampsia, a significant cause of maternal morbidity and mortality. This lack of knowledge may impact their ability to report symptoms, comply with recommendations, and receive appropriate follow-up care. Pregnant people commonly seek information from sources outside their treating clinician, including pregnancy-specific books and online sources. We examined commonly used preeclampsia information sources to evaluate whether pregnant people are receiving up-to-date, guideline-based information. METHODS: We conducted a content analysis of preeclampsia-related information in top-ranking websites and bestselling pregnancy books. We used American College of Obstetricians and Gynecologists preeclampsia guidelines to construct a codebook, which we used to examine source content completeness and accuracy. For each source, we analyzed information about preeclampsia diagnosis, patient-reported symptoms, risk factors, prevention, treatment, and complications. RESULTS: Across 19 included sources (13 websites and 6 books), we found substantial variation in completeness and accuracy of preeclampsia information. We found high rates of mentions for preeclampsia symptoms. Risk factors were more commonly included in online sources than book sources. Most sources mentioned treatment options, including blood pressure medication and giving birth; however, one-third of online sources positively mentioned the nonrecommended treatment of bed rest. Prevention methods, including prenatal aspirin for high-risk pregnancies, and long-term complications of preeclampsia were infrequently mentioned. CONCLUSIONS: Varying rates of accuracy in patient-facing preeclampsia information mean there is substantial room for improvement in these sources. Ensuring pregnant people receive current guideline-based information is critical for improving outcomes and implementing shared decision-making.

Cortical change after a 2-week novel robotic rehabilitation program in children with prior hemispherectomy: pilot imaging study.

INTRODUCTION: Partial preservation of sensory and motor functions in the contralateral extremities after hemispherectomy is likely secondary to cortical reorganization of the remaining hemisphere and can be improved by rehabilitation. This study aims to investigate behavioral and structural cerebral cortical changes that may occur after a 2-week novel robotic rehabilitation program in children with prior anatomic hemispherectomy. METHODS: Five patients with prior anatomic hemispherectomy (average age 10.8 years; all female) participated in a 2-week novel robotic rehabilitation program. Pre- and post-treatment (2 time points) high-resolution structural 3D FSPGR (fast spoiled gradient echo) magnetic resonance images were analyzed to measure cortical thickness and gray matter volume using a locally designed image processing pipeline. RESULTS: Four of the five patients showed improvement in the Fugl-Meyer score (average increase 2.5 + 2.1 SD. Individual analyses identified small increases in gray matter volume near the hand knob area of the primary cortex in three of the five patients. Group analyses identified an increase in cortical thickness near the hand knob area of the primary motor cortex, in addition to other sensorimotor regions. CONCLUSION: This small pilot study demonstrates that potentially rehabilitation-associated cortical changes can be identified with MRI in hemispherectomy patients.

Corrigendum: Patterned hippocampal stimulation facilitates memory in patients with a history of head impact and/or brain injury.

[This corrects the article DOI: 10.3389/fnhum.2022.933401.].

Artifact propagation in subdural cortical electrostimulation: Characterization and modeling.

Cortical stimulation via electrocorticography (ECoG) may be an effective method for inducing artificial sensation in bi-directional brain-computer interfaces (BD-BCIs). However, strong electrical artifacts caused by electrostimulation may significantly degrade or obscure neural information. A detailed understanding of stimulation artifact propagation through relevant tissues may improve existing artifact suppression techniques or inspire the development of novel artifact mitigation strategies. Our work thus seeks to comprehensively characterize and model the propagation of artifacts in subdural ECoG stimulation. To this end, we collected and analyzed data from eloquent cortex mapping procedures of four subjects with epilepsy who were implanted with subdural ECoG electrodes. From this data, we observed that artifacts exhibited phase-locking and ratcheting characteristics in the time domain across all subjects. In the frequency domain, stimulation caused broadband power increases, as well as power bursts at the fundamental stimulation frequency and its super-harmonics. The spatial distribution of artifacts followed the potential distribution of an electric dipole with a median goodness-of-fit of R 2 = 0.80 across all subjects and stimulation channels. Artifacts as large as ±1,100 µV appeared anywhere from 4.43 to 38.34 mm from the stimulation channel. These temporal, spectral and spatial characteristics can be utilized to improve existing artifact suppression techniques, inspire new strategies for artifact mitigation, and aid in the development of novel cortical stimulation protocols. Taken together, these findings deepen our understanding of cortical electrostimulation and provide critical design specifications for future BD-BCI systems.

Patterned Hippocampal Stimulation Facilitates Memory in Patients With a History of Head Impact and/or Brain Injury.

RATIONALE: Deep brain stimulation (DBS) of the hippocampus is proposed for enhancement of memory impaired by injury or disease. Many pre-clinical DBS paradigms can be addressed in epilepsy patients undergoing intracranial monitoring for seizure localization, since they already have electrodes implanted in brain areas of interest. Even though epilepsy is usually not a memory disorder targeted by DBS, the studies can nevertheless model other memory-impacting disorders, such as Traumatic Brain Injury (TBI). METHODS: Human patients undergoing Phase II invasive monitoring for intractable epilepsy were implanted with depth electrodes capable of recording neurophysiological signals. Subjects performed a delayed-match-to-sample (DMS) memory task while hippocampal ensembles from CA1 and CA3 cell layers were recorded to estimate a multi-input, multi-output (MIMO) model of CA3-to-CA1 neural encoding and a memory decoding model (MDM) to decode memory information from CA3 and CA1 neuronal signals. After model estimation, subjects again performed the DMS task while either MIMO-based or MDM-based patterned stimulation was delivered to CA1 electrode sites during the encoding phase of the DMS trials. Each subject was sorted (post hoc) by prior experience of repeated and/or mild-to-moderate brain injury (RMBI), TBI, or no history (control) and scored for percentage successful delayed recognition (DR) recall on stimulated vs. non-stimulated DMS trials. The subject's medical history was unknown to the experimenters until after individual subject memory retention results were scored. RESULTS: When examined compared to control subjects, both TBI and RMBI subjects showed increased memory retention in response to both MIMO and MDM-based hippocampal stimulation. Furthermore, effects of stimulation were also greater in subjects who were evaluated as having pre-existing mild-to-moderate memory impairment. CONCLUSION: These results show that hippocampal stimulation for memory facilitation was more beneficial for subjects who had previously suffered a brain injury (other than epilepsy), compared to control (epilepsy) subjects who had not suffered a brain injury. This study demonstrates that the epilepsy/intracranial recording model can be extended to test the ability of DBS to restore memory function in subjects who previously suffered a brain injury other than epilepsy, and support further investigation into the beneficial effect of DBS in TBI patients.

A Qualitative Investigation of the Experiences of Tobacco Use among U.S. Adults with Food Insecurity.

BACKGROUND: Low-income U.S. adults experiencing food insecurity have a disproportionately high prevalence of cigarette smoking, and quantitative studies suggest that food insecurity is a barrier to quitting. To guide effective tobacco control strategies, this study aimed to understand the experiences, perceptions, and context of tobacco use and cessation among low-income populations experiencing food insecurity. METHODS: We conducted in-depth, semi-structured interviews with 23 adults who were currently smoking cigarettes and were experiencing food insecurity, mostly living in rural settings. Participants were recruited through food-pantry-based needs assessment surveys and study flyers in community-based organizations. The interview guide explored participants' histories of smoking, the role and function of tobacco in their lives, their interest in and barriers to quitting, as well as lived experiences of food insecurity. We used reflexive thematic analysis to analyze transcribed interviews. RESULTS: Within a broader context of structural challenges related to poverty and financial strain that shaped current smoking behavior and experiences with food insecurity, we identified the following five themes: smoking to ignore hunger or eat less; staying addicted to smoking in the midst of instability; smoking being prioritized in the midst of financial strain; life stressors and the difficulty of quitting smoking and staying quit; and childhood adversity at the intersection of food insecurity and tobacco use. CONCLUSION: The context of tobacco use among adults with food insecurity was highly complex. To effectively address tobacco-related disparities among those who are socially and economically disadvantaged, tobacco control efforts should consider relevant lived experiences and structural constraints intersecting smoking and food insecurity. Findings are applied to a conceptualization of clustering of conditions contributing to nicotine dependence, food insecurity, and stress.

Spatiotemporal Trends of Legacy and Alternative Flame Retardants in Harbor Seals from the Coasts of California, the Gulf of Maine, and Sweden.

Temporal trends of polybrominated diphenyl ethers (PBDEs) have been extensively studied in various environmental compartments globally. However, despite the increasing use of alternative flame retardants following PBDE bans, the spatiotemporal trends of these replacements have rarely been studied, and the available results are often inconsistent. In the present study, we retrospectively investigated the spatiotemporal trends of PBDEs and a suite of alternative brominated FRs (aBFRs) and chlorinated FRs (i.e., dechloranes or DECs) in three harbor seal (Phoca vitulina) populations from the coasts of California, the Gulf of Maine, and southern Sweden during 1999-2016. We observed significantly decreasing trends of ΣPBDEs in all the three populations at an annual rate of 9-11%, which were predominantly driven by the declining concentrations of tetra- and penta-BDEs. The levels of ΣaBFRs decreased significantly in seals from California (mainly 1,3,5-tribromobenzene) and Sweden (mainly hexabromobenzene), while no trend was observed for those from Maine. By contrast, DECs (dominated by DEC 602) did not decrease significantly in any population. Compared with the consistent PBDE congener profiles across regions, aBFRs and DECs exhibited varying compositional profiles between regions, likely indicating region-specific sources of these alternative FR mixtures. Spatial analysis also revealed regional differences in the concentrations of PBDEs, aBFRs, and DECs in harbor seals. Our reconstructed spatiotemporal trends suggest the effective regulation of commercial penta-BDE mix in these regions and warrant further monitoring of the higher brominated BDEs and alternative FRs.