Multiple objects evoke fluctuating responses in several regions of the visual pathway.

How neural representations preserve information about multiple stimuli is mysterious. Because tuning of individual neurons is coarse (e.g., visual receptive field diameters can exceed perceptual resolution), the populations of neurons potentially responsive to each individual stimulus can overlap, raising the question of how information about each item might be segregated and preserved in the population. We recently reported evidence for a potential solution to this problem: when two stimuli were present, some neurons in the macaque visual cortical areas V1 and V4 exhibited fluctuating firing patterns, as if they responded to only one individual stimulus at a time (Jun et al., 2022). However, whether such an information encoding strategy is ubiquitous in the visual pathway and thus could constitute a general phenomenon remains unknown. Here, we provide new evidence that such fluctuating activity is also evoked by multiple stimuli in visual areas responsible for processing visual motion (middle temporal visual area, MT), and faces (middle fundus and anterolateral face patches in inferotemporal cortex - areas MF and AL), thus extending the scope of circumstances in which fluctuating activity is observed. Furthermore, consistent with our previous results in the early visual area V1, MT exhibits fluctuations between the representations of two stimuli when these form distinguishable objects but not when they fuse into one perceived object, suggesting that fluctuating activity patterns may underlie visual object formation. Taken together, these findings point toward an updated model of how the brain preserves sensory information about multiple stimuli for subsequent processing and behavioral action.

Orthogonal neural representations support perceptual judgements of natural stimuli.

In natural behavior, observers must separate relevant information from a barrage of irrelevant information. Many studies have investigated the neural underpinnings of this ability using artificial stimuli presented on simple backgrounds. Natural viewing, however, carries a set of challenges that are inaccessible using artificial stimuli, including neural responses to background objects that are task-irrelevant. An emerging body of evidence suggests that the visual abilities of humans and animals can be modeled through the linear decoding of task-relevant information from visual cortex. This idea suggests the hypothesis that irrelevant features of a natural scene should impair performance on a visual task only if their neural representations intrude on the linear readout of the task relevant feature, as would occur if the representations of task-relevant and irrelevant features are not orthogonal in the underlying neural population. We tested this hypothesis using human psychophysics and monkey neurophysiology, in response to parametrically variable naturalistic stimuli. We demonstrate that 1) the neural representation of one feature (the position of a central object) in visual area V4 is orthogonal to those of several background features, 2) the ability of human observers to precisely judge object position was largely unaffected by task-irrelevant variation in those background features, and 3) many features of the object and the background are orthogonally represented by V4 neural responses. Our observations are consistent with the hypothesis that orthogonal neural representations support stable perception of objects and features despite the tremendous richness of natural visual scenes.

Task interference as a neuronal basis for the cost of cognitive flexibility.

Humans and animals have an impressive ability to juggle multiple tasks in a constantly changing environment. This flexibility, however, leads to decreased performance under uncertain task conditions. Here, we combined monkey electrophysiology, human psychophysics, and artificial neural network modeling to investigate the neuronal mechanisms of this performance cost. We developed a behavioural paradigm to measure and influence participants' decision-making and perception in two distinct perceptual tasks. Our data revealed that both humans and monkeys, unlike an artificial neural network trained for the same tasks, make less accurate perceptual decisions when the task is uncertain. We generated a mechanistic hypothesis by comparing this neural network trained to produce correct choices with another network trained to replicate the participants' choices. We hypothesized, and confirmed with further behavioural, physiological, and causal experiments, that the cost of task flexibility comes from what we term task interference. Under uncertain conditions, interference between different tasks causes errors because it results in a stronger representation of irrelevant task features and entangled neuronal representations of different features. Our results suggest a tantalizing, general hypothesis: that cognitive capacity limitations, both in health and disease, stem from interference between neural representations of different stimuli, tasks, or memories.

Targeted V1 comodulation supports task-adaptive sensory decisions.

Sensory-guided behavior requires reliable encoding of stimulus information in neural populations, and flexible, task-specific readout. The former has been studied extensively, but the latter remains poorly understood. We introduce a theory for adaptive sensory processing based on functionally-targeted stochastic modulation. We show that responses of neurons in area V1 of monkeys performing a visual discrimination task exhibit low-dimensional, rapidly fluctuating gain modulation, which is stronger in task-informative neurons and can be used to decode from neural activity after few training trials, consistent with observed behavior. In a simulated hierarchical neural network model, such labels are learned quickly and can be used to adapt downstream readout, even after several intervening processing stages. Consistently, we find the modulatory signal estimated in V1 is also present in the activity of simultaneously recorded MT units, and is again strongest in task-informative neurons. These results support the idea that co-modulation facilitates task-adaptive hierarchical information routing.

Tai Chi as a Complementary Therapy for Depression and Anxiety Among U.S. Veterans in a Mental Health Inpatient Setting.

BACKGROUND: Depression and anxiety are two of the top five mental illnesses veterans report. Treatment for depression and anxiety includes medications and psychiatric treatment in inpatient, outpatient, and residential treatment programs; the use of complementary and alternative medicine (CAM) can have beneficial results by decreasing symptoms, recognize patients' preference for CAM, and be cost-effective. AIM: This study aimed to evaluate the effects of Tai Chi on depression and anxiety symptoms on inpatient psychosocial or substance use disorder (SUD) rehabilitation treatment program residents since little evidence exists regarding the effectiveness of Tai Chi on participants in residential mental health treatment programs. METHOD: A mixed-method, cohort design with 88 participants (41 usual treatment without Tai Chi, 47 intervention) used a demographic survey, Hamilton Anxiety Scale, Quick Inventory of Depressive Symptomatology, self-report, and the Patient Health Questionnaire-9 at Weeks 1 and 4 of the treatment program. After Week 4, the intervention group responded to six open-ended questions about Tai Chi's effects on their overall depression and anxiety. RESULTS: The anxiety level of the intervention group was significantly decreased, as evidenced by the Hamilton Anxiety Scale scores (p = .02). However, the measures of depression did not differ between the groups. Two themes, mindfulness and satisfaction, were identified from the written responses regarding the Tai Chi intervention. CONCLUSION: Tai Chi effectively reduced symptoms of anxiety that varied by age and ethnicity. This study increased the insight regarding the benefit of including Tai Chi as a complementary therapy for those participating in residential treatment programs.

Contributions of early and mid-level visual cortex to high-level object categorization.

The complexity of visual features for which neurons are tuned increases from early to late stages of the ventral visual stream. Thus, the standard hypothesis is that high-level functions like object categorization are primarily mediated by higher visual areas because they require more complex image formats that are not evident in early visual processing stages. However, human observers can categorize images as objects or animals or as big or small even when the images preserve only some low- and mid-level features but are rendered unidentifiable ('texforms', Long et al., 2018). This observation suggests that even the early visual cortex, in which neurons respond to simple stimulus features, may already encode signals about these more abstract high-level categorical distinctions. We tested this hypothesis by recording from populations of neurons in early and mid-level visual cortical areas while rhesus monkeys viewed texforms and their unaltered source stimuli (simultaneous recordings from areas V1 and V4 in one animal and separate recordings from V1 and V4 in two others). Using recordings from a few dozen neurons, we could decode the real-world size and animacy of both unaltered images and texforms. Furthermore, this neural decoding accuracy across stimuli was related to the ability of human observers to categorize texforms by real-world size and animacy. Our results demonstrate that neuronal populations early in the visual hierarchy contain signals useful for higher-level object perception and suggest that the responses of early visual areas to simple stimulus features display preliminary untangling of higher-level distinctions.

Multiple objects evoke fluctuating responses in several regions of the visual pathway.

How neural representations preserve information about multiple stimuli is mysterious. Because tuning of individual neurons is coarse (for example, visual receptive field diameters can exceed perceptual resolution), the populations of neurons potentially responsive to each individual stimulus can overlap, raising the question of how information about each item might be segregated and preserved in the population. We recently reported evidence for a potential solution to this problem: when two stimuli were present, some neurons in the macaque visual cortical areas V1 and V4 exhibited fluctuating firing patterns, as if they responded to only one individual stimulus at a time. However, whether such an information encoding strategy is ubiquitous in the visual pathway and thus could constitute a general phenomenon remains unknown. Here we provide new evidence that such fluctuating activity is also evoked by multiple stimuli in visual areas responsible for processing visual motion (middle temporal visual area, MT), and faces (middle fundus and anterolateral face patches in inferotemporal cortex - areas MF and AL), thus extending the scope of circumstances in which fluctuating activity is observed. Furthermore, consistent with our previous results in the early visual area V1, MT exhibits fluctuations between the representations of two stimuli when these form distinguishable objects but not when they fuse into one perceived object, suggesting that fluctuating activity patterns may underlie visual object formation. Taken together, these findings point toward an updated model of how the brain preserves sensory information about multiple stimuli for subsequent processing and behavioral action. Impact Statement: We find neural fluctuations in multiple areas along the visual cortical hierarchy that could allow the brain to represent distinct co-occurring visual stimuli.

Topological insights into the neural basis of flexible behavior.

It is widely accepted that there is an inextricable link between neural computations, biological mechanisms, and behavior, but it is challenging to simultaneously relate all three. Here, we show that topological data analysis (TDA) provides an important bridge between these approaches to studying how brains mediate behavior. We demonstrate that cognitive processes change the topological description of the shared activity of populations of visual neurons. These topological changes constrain and distinguish between competing mechanistic models, are connected to subjects' performance on a visual change detection task, and, via a link with network control theory, reveal a tradeoff between improving sensitivity to subtle visual stimulus changes and increasing the chance that the subject will stray off task. These connections provide a blueprint for using TDA to uncover the biological and computational mechanisms by which cognition affects behavior in health and disease.

The Experience of Frontline Nurses during the COVID-19 Pandemic: A Phenomenological Study.

The purpose of this phenomenological study was to describe the experience of frontline nurses working during the COVID-19 pandemic. The first author conducted two individual audiotaped interviews with 23 qualified staff nurses. All the authors analyzed the professionally transcribed data according to hermeneutic principles. The researchers identified five major themes: (a) we are family; (b) heroes work here; (c) fear of contagion; (d) mental health and well-being; and (e) new reality. Given the uncertainties of working during the COVID-19 pandemic, findings revealed the value of supportive collegial relationships and the need to support the mental health and well-being needs of frontline nurses during the pandemic. Nurses need supportive environments to help ease the challenges associated with serving on the frontline during times of crisis. Findings have implications for future public health preparedness and response efforts.

Coordinated multiplexing of information about separate objects in visual cortex.

Sensory receptive fields are large enough that they can contain more than one perceptible stimulus. How, then, can the brain encode information about each of the stimuli that may be present at a given moment? We recently showed that when more than one stimulus is present, single neurons can fluctuate between coding one vs. the other(s) across some time period, suggesting a form of neural multiplexing of different stimuli (Caruso et al., 2018). Here, we investigate (a) whether such coding fluctuations occur in early visual cortical areas; (b) how coding fluctuations are coordinated across the neural population; and (c) how coordinated coding fluctuations depend on the parsing of stimuli into separate vs. fused objects. We found coding fluctuations do occur in macaque V1 but only when the two stimuli form separate objects. Such separate objects evoked a novel pattern of V1 spike count ('noise') correlations involving distinct distributions of positive and negative values. This bimodal correlation pattern was most pronounced among pairs of neurons showing the strongest evidence for coding fluctuations or multiplexing. Whether a given pair of neurons exhibited positive or negative correlations depended on whether the two neurons both responded better to the same object or had different object preferences. Distinct distributions of spike count correlations based on stimulus preferences were also seen in V4 for separate objects but not when two stimuli fused to form one object. These findings suggest multiple objects evoke different response dynamics than those evoked by single stimuli, lending support to the multiplexing hypothesis and suggesting a means by which information about multiple objects can be preserved despite the apparent coarseness of sensory coding.

Effects of Implementing an Acuity Tool on a Psychiatric Intensive Care Unit.

BACKGROUND: Staff shortages, reduced budgets, and high acuity of violent psychiatric patients can create challenges in psychiatric intensive care units (PICUs). LOCAL PROBLEM: Staffing of the psychiatric unit was based on patient census rather than evidence-based practices. METHODS: A pre-/postintervention design was used to examine changes in nursing satisfaction and patient outcomes as measured with the National Database of Nursing Quality Indicators (NDNQI) survey results. INTERVENTIONS: A psychiatric specific acuity tool was implemented on the PICU of a Veterans Administration hospital. RESULTS: After an initial decrease related to the COVID-19 pandemic, total acuity and the total number of nurses remained relatively stable while the unit census declined. NDNQI survey results improved with the largest being a 52-percentile increase for the quality-of-care summary measure. CONCLUSIONS: An acuity tool can help standardize practice, determine fair patient assignments among staff, increase nurse satisfaction, and promote best practices for patient safety.

A general decoding strategy explains the relationship between behavior and correlated variability.

Improvements in perception are frequently accompanied by decreases in correlated variability in sensory cortex. This relationship is puzzling because overall changes in correlated variability should minimally affect optimal information coding. We hypothesize that this relationship arises because instead of using optimal strategies for decoding the specific stimuli at hand, observers prioritize generality: a single set of neuronal weights to decode any stimuli. We tested this using a combination of multineuron recordings in the visual cortex of behaving rhesus monkeys and a cortical circuit model. We found that general decoders optimized for broad rather than narrow sets of visual stimuli better matched the animals' decoding strategy, and that their performance was more related to the magnitude of correlated variability. In conclusion, the inverse relationship between perceptual performance and correlated variability can be explained by observers using a general decoding strategy, capable of decoding neuronal responses to the variety of stimuli encountered in natural vision.

Dynamic task-belief is an integral part of decision-making.

Natural decisions involve two seemingly separable processes: inferring the relevant task (task-belief) and performing the believed-relevant task. The assumed separability has led to the traditional practice of studying task-switching and perceptual decision-making individually. Here, we used a novel paradigm to manipulate and measure macaque monkeys' task-belief and demonstrated inextricable neuronal links between flexible task-belief and perceptual decision-making. We showed that in animals, but not in artificial networks that performed as well or better than the animals, stronger task-belief is associated with better perception. Correspondingly, recordings from neuronal populations in cortical areas 7a and V1 revealed that stronger task-belief is associated with better discriminability of the believed-relevant, but not the believed-irrelevant, feature. Perception also impacts belief updating; noise fluctuations in V1 help explain how task-belief is updated. Our results demonstrate that complex tasks and multi-area recordings can reveal fundamentally new principles of how biology affects behavior in health and disease.

Methylphenidate as a causal test of translational and basic neural coding hypotheses.

Most systems neuroscience studies fall into one of two categories: basic science work aimed at understanding the relationship between neurons and behavior, or translational work aimed at developing treatments for neuropsychiatric disorders. Here we use these two approaches to inform and enhance each other. Our study both tests hypotheses about basic science neural coding principles and elucidates the neuronal mechanisms underlying clinically relevant behavioral effects of systemically administered methylphenidate (Ritalin). We discovered that orally administered methylphenidate, used clinically to treat attention deficit hyperactivity disorder (ADHD) and generally to enhance cognition, increases spatially selective visual attention, enhancing visual performance at only the attended location. Further, we found that this causal manipulation enhances vision in rhesus macaques specifically when it decreases the mean correlated variability of neurons in visual area V4. Our findings demonstrate that the visual system is a platform for understanding the neural underpinnings of both complex cognitive processes (basic science) and neuropsychiatric disorders (translation). Addressing basic science hypotheses, our results are consistent with a scenario in which methylphenidate has cognitively specific effects by working through naturally selective cognitive mechanisms. Clinically, our findings suggest that the often staggeringly specific symptoms of neuropsychiatric disorders may be caused and treated by leveraging general mechanisms.

Priority coding in the visual system.

Although we are continuously bombarded with visual input, only a fraction of incoming visual events is perceived, remembered or acted on. The neural underpinnings of various forms of visual priority coding, including perceptual expertise, goal-directed attention, visual salience, image memorability and preferential looking, have been studied. Here, we synthesize information from these different examples to review recent developments in our understanding of visual priority coding and its neural correlates, with a focus on the role of behaviour to evaluate candidate correlates. We propose that the brain combines different types of priority into a unified priority signal while also retaining the ability to differentiate between them, and that this happens by leveraging partially overlapping low-dimensional neural subspaces for each type of priority that are shared with the downstream neural populations involved in decision-making. Finally, we describe the gulfs in understanding that have resulted from different research approaches, and we point towards future directions that will lead to fundamental insights about neural coding and how prioritization influences visually guided behaviours.

Comparison of Recertification Methods on CPR Quality.

BACKGROUND: High-quality cardiopulmonary resuscitation (CPR) is vital to improving survival from cardiac arrest. This study compared participant performance of CPR with three American Heart Association (AHA)-approved CPR recertification programs because current literature does not show which method is superior. Our goal is to investigate the best training methods to deliver high-quality CPR. METHOD: Participants were within 90 days of recertification in face-to-face, Heart Code, or Resuscitation Quality Improvement (RQI). RESULTS: No statistically significant differences were found among training modalities or demographic characteristics. The only significant difference was among those who had performed CPR on a human. CONCLUSION: Mean scores for the three modalities did not reach the passing requirement for AHA, suggesting that one method of CPR training is not better than the others. Recommendations for translating these findings into clinical practice include mock codes with the ability to measure CPR metrics and simulations of cardiac responses to provide vicarious CPR experience. [J Contin Educ Nurs. 2022;53(1):43-48.].

Clinical Nurses Research Priorities in Hospital Settings: A Delphi Survey.

This study aimed to identify the research priorities of clinical nurses to develop a research program at a health care services system that includes three hospitals. A Delphi survey was emailed to all clinical nurses in two rounds. The Delphi method was used to collect data from the nurses in regards to their priority research themes, and the data were analyzed using descriptive and comparative statistics. A total of 933 clinical nurses returned the first round of the Delphi survey and 543 nurses answered the second round. Clinical nurses identified 89 potential research themes. Patient safety and ethical challenges were the two highest ranked research priorities. The 40 highest ranked priority research themes were closely associated with issues concerning patient care and ethics. However, the nurses also gave high ratings to issues relating to the work environment, questions about technology implementation, and patient involvement in clinical care decisions.

Attention improves information flow between neuronal populations without changing the communication subspace.

Visual attention allows observers to change the influence of different parts of a visual scene on their behavior, suggesting that information can be flexibly shared between visual cortex and neurons involved in decision making. We investigated the neural substrate of flexible information routing by analyzing the activity of populations of visual neurons in the medial temporal area (MT) and oculo-motor neurons in the superior colliculus (SC) while rhesus monkeys switched spatial attention. We demonstrated that attention increases the efficacy of visuomotor communication: trial-to-trial variability in SC population activity could be better predicted by the activity of the MT population (and vice versa) when attention was directed toward their joint receptive fields. Surprisingly, this improvement in prediction was not explained by changes in the dimensionality of the shared subspace or in the magnitude of local or shared pairwise noise correlations. These results lay a foundation for future theoretical and experimental studies into how visual attention can flexibly change information flow between sensory and decision neurons.

Symptom and Illness Experience for English and Spanish-Speaking Children with Advanced Cancer: Child and Parent Perspective.

Understanding the symptom and illness experience of children with advanced cancer facilitates quality care; yet, obtaining this understanding is complicated by the child's developmental level and physical and psychological health factors that affect communication. The purpose of this study was to describe the symptom and illness experience of English- and Spanish-speaking children with advanced cancer as described by the child and parent. We conducted hermeneutic phenomenological, descriptive, and interpretive interviews with eligible children and parents. The interdisciplinary research team analyzed transcripts hermeneutically until consensus on theme labels was reached. Four themes and associated subthemes were identified from the interviews of the 10 child-parent dyads: 1. symptoms disrupt life (path to diagnosis, life is disrupted), 2. isolation (lack of understanding, family separations/relationships), 3. protection, and 4. death is not for children. Children and parents readily described the impact symptoms and cancer treatment had on their lives and relationships. These findings underscore the salient aspects of daily life disrupted by cancer. With a deeper understanding of symptom burden and its interference, relationship and communication implications, and anticipatory grief, the treating team may better optimize care for children and their families living with advanced cancer.

Impact of an Extended Nursing Shift Schedule in a Rural and Urban Primary Care Setting.

Two primary care clinics in rural and urban settings implemented a 9-hour nursing shift schedule. The purpose of this project was to use a quasiexperimental mixed-methods research design to assess outcomes for a 1-year implementation of nursing staff maintaining 9-hour shifts. Pre- and postdata were collected before and after implementation. The rural clinic demonstrated significant improvements in nurse satisfaction, overtime, compensatory time, and postacute follow-up. The urban facility showed significant decreases in sick leave. Patient satisfaction scores did not show significant changes for either clinic.