Memorable first impressions.

Our ability to recall details from a remembered image depends on a single mechanism that is engaged from the very moment the image disappears from view.

Conditional independence as a statistical assessment of evidence integration processes.

Intuitively, combining multiple sources of evidence should lead to more accurate decisions than considering single sources of evidence individually. In practice, however, the proper computation may be difficult, or may require additional data that are inaccessible. Here, based on the concept of conditional independence, we consider expressions that can serve either as recipes for integrating evidence based on limited data, or as statistical benchmarks for characterizing evidence integration processes. Consider three events, A, B, and C. We find that, if A and B are conditionally independent with respect to C, then the probability that C occurs given that both A and B are known, P(C|A, B), can be easily calculated without the need to measure the full three-way dependency between A, B, and C. This simplified approach can be used in two general ways: to generate predictions by combining multiple (conditionally independent) sources of evidence, or to test whether separate sources of evidence are functionally independent of each other. These applications are demonstrated with four computer-simulated examples, which include detecting a disease based on repeated diagnostic testing, inferring biological age based on multiple biomarkers of aging, discriminating two spatial locations based on multiple cue stimuli (multisensory integration), and examining how behavioral performance in a visual search task depends on selection histories. Besides providing a sound prescription for predicting outcomes, this methodology may be useful for analyzing experimental data of many types.

Coupling of saccade plans to endogenous attention during urgent choices.

The neural mechanisms that willfully direct attention to specific locations in space are closely related to those for generating targeting eye movements (saccades). However, the degree to which the voluntary deployment of attention to a location is necessarily accompanied by a corresponding saccade plan remains unclear. One problem is that attention and saccades are both automatically driven by salient sensory events; another is that the underlying processes unfold within tens of milliseconds only. Here, we use an urgent task design to resolve the evolution of a visuomotor choice on a moment-by-moment basis while independently controlling the endogenous (goal-driven) and exogenous (salience-driven) contributions to performance. Human participants saw a peripheral cue and, depending on its color, either looked at it (prosaccade) or looked at a diametrically opposite, uninformative non-cue (antisaccade). By varying the luminance of the stimuli, the exogenous contributions could be cleanly dissociated from the endogenous process guiding the choice over time. According to the measured timecourses, generating a correct antisaccade requires about 30 ms more processing time than generating a correct prosaccade based on the same perceptual signal. The results indicate that saccade plans are biased toward the location where attention is endogenously deployed, but the coupling is weak and can be willfully overridden very rapidly.

Conditional independence as a statistical assessment of evidence integration processes.

Intuitively, combining multiple sources of evidence should lead to more accurate decisions than considering single sources of evidence individually. In practice, however, the proper computation may be difficult, or may require additional data that are inaccessible. Here, based on the concept of conditional independence, we consider expressions that can serve either as recipes for integrating evidence based on limited data, or as statistical benchmarks for characterizing evidence integration processes. Consider three events, A, B, and C. We find that, if A and B are conditionally independent with respect to C, then the probability that C occurs given that both A and B are known, PC|A,B, can be easily calculated without the need to measure the full three-way dependency between A, B, and C. This simplified approach can be used in two general ways: to generate predictions by combining multiple (conditionally independent) sources of evidence, or to test whether separate sources of evidence are functionally independent of each other. These applications are demonstrated with four computer-simulated examples, which include detecting a disease based on repeated diagnostic testing, inferring biological age based on multiple biomarkers of aging, discriminating two spatial locations based on multiple cue stimuli (multisensory integration), and examining how behavioral performance in a visual search task depends on selection histories. Besides providing a sound prescription for predicting outcomes, this methodology may be useful for analyzing experimental data of many types.

Stimulus salience conflicts and colludes with endogenous goals during urgent choices.

Selecting where to look next depends on both the salience of objects and current goals (what we are looking for), but discerning their relative contributions over the time frame of typical visuomotor decisions (200-250 ms) has been difficult. Here we investigate this problem using an urgent choice task with which the two contributions can be dissociated and tracked moment by moment. Behavioral data from three monkeys corresponded with model-based predictions: when salience favored the target, perceptual performance evolved rapidly and steadily toward an asymptotic level; when salience favored the distracter, many rapid errors were produced and the rise in performance took more time-effects analogous to oculomotor and attentional capture. The results show that salience has a brief (∼50 ms) but inexorable impact that leads to exogenous, involuntary capture, and this can either help or hinder performance, depending on the alignment between salience and ongoing internal goals.

A conflict between spatial selection and evidence accumulation in area LIP.

The lateral intraparietal area (LIP) contains spatially selective neurons that help guide eye movements and, according to numerous studies, do so by accumulating sensory evidence in favor of one choice (e.g., look left) or another (look right). To examine this functional link, we trained two monkeys on an urgent motion discrimination task, a task with which the evolution of both the recorded neuronal activity and the subject's choice can be tracked millisecond by millisecond. We found that while choice accuracy increased steeply with increasing sensory evidence, at the same time, the LIP selection signal became progressively weaker, as if it hindered performance. This effect was consistent with the transient deployment of spatial attention to disparate locations away from the relevant sensory cue. The results demonstrate that spatial selection in LIP is dissociable from, and may even conflict with, evidence accumulation during informed saccadic choices.

Exogenous capture accounts for fundamental differences between pro- and antisaccade performance.

To generate the next eye movement, oculomotor circuits take into consideration the physical salience of objects in view and current behavioral goals, exogenous and endogenous influences, respectively. However, the interactions between exogenous and endogenous mechanisms and their dynamic contributions to target selection have been difficult to resolve because they evolve extremely rapidly. In a recent study (Salinas et al., 2019), we achieved the necessary temporal precision using an urgent variant of the antisaccade task wherein motor plans are initiated early and choice accuracy depends sharply on when exactly the visual cue information becomes available. Empirical and modeling results indicated that the exogenous signal arrives ∼80 ms after cue onset and rapidly accelerates the (incorrect) plan toward the cue, whereas the informed endogenous signal arrives ∼25 ms later to favor the (correct) plan away from the cue. Here, we scrutinize a key mechanistic hypothesis about this dynamic, that the exogenous and endogenous signals act at different times and independently of each other. We test quantitative model predictions by comparing the performance of human participants instructed to look toward a visual cue or away from it under high urgency. We find that, indeed, the exogenous response is largely impervious to task instructions; it simply flips its sign relative to the correct choice, and this largely explains the drastic differences in psychometric performance between the two tasks. Thus, saccadic choices are strongly dictated by the alignment between salience and behavioral goals.

Under time pressure, the exogenous modulation of saccade plans is ubiquitous, intricate, and lawful.

The choice of where to look next is determined by both exogenous (bottom-up) and endogenous (top-down) factors, but details of their interaction and distinct contributions to target selection have remained elusive. Recent experiments with urgent choice tasks, in which stimuli are evaluated while motor plans are already advancing, have greatly clarified these contributions. Specifically, exogenous modulations associated with stimulus detection act rapidly and briefly (∼25 ms) to automatically halt and/or boost ongoing motor plans as per spatial congruence rules. These stereotypical modulations explain, in quantitative detail, characteristic features of many saccadic tasks (e.g. antisaccade, countermanding, saccadic-inhibition, gap, and double-step). Thus, the same low-level visuomotor interactions contribute to diverse oculomotor phenomena traditionally attributed to different neural mechanisms.

Urgent Decision Making: Resolving Visuomotor Interactions at High Temporal Resolution.

Measuring when exactly perceptual decisions are made is crucial for defining how the activation of specific neurons contributes to behavior. However, in traditional, nonurgent visuomotor tasks, the uncertainty of this temporal measurement is very large. This is a problem not only for delimiting the capacity of perception, but also for correctly interpreting the functional roles ascribed to choice-related neuronal responses. In this article, we review psychophysical, neurophysiological, and modeling work based on urgent visuomotor tasks in which this temporal uncertainty can be effectively overcome. The cornerstone of this work is a novel behavioral metric that describes the evolution of the subject's perceptual judgment moment by moment, allowing us to resolve numerous perceptual events that unfold within a few tens of milliseconds. In this framework, the neural distinction between perceptual evaluation and motor selection processes becomes particularly clear, as the conclusion of one is not contingent on that of the other.

Tumor filodes benigno de la vulva: reporte de un caso / Benign phyllodes tumor of the vulva: Case Report

Resumen: ANTECEDENTES: El tumor filodes de la vulva es una lesión proliferativa, benigna, poco común, que comparte características similares con los tumores mamarios. Aparece en forma de masa unilateral, no dolorosa, localizada en los labios mayores o menores, y en la horquilla posterior de la vulva. Hasta la fecha se han reportado 30 casos de tumor filodes vulvar en todo el mundo. Debido a su baja incidencia no se han estimado los datos epidemiológicos y fisiopatológicos concretos de la enfermedad. CASO CLÍNICO: Paciente de 20 años, que acudió a consulta debido a la aparición de una masa vulvar de aproximadamente 11 cm en el labio mayor izquierdo, no dolorosa, de crecimiento rápido. El tratamiento consistió en resección quirúrgica. El diagnóstico presuntivo fue fibroma vulvar. El servicio de Anatomopatología reportó: tumoración de 280 g, de 12 x 7 x 6 cm, con bordes y formas irregulares, multinodular, cubierta por piel con epidermis; superficie sólida, con bordes irregulares, de aspecto frondoso y consistencia blanda. Se estableció el diagnóstico de tumor filodes de bajo grado (benigno). CONCLUSIÓN: El tumor filodes de la vulva es una alteración excepcional, por lo que es importante conocer sus manifestaciones clínicas, características macro y microscópicas para establecer el diagnóstico y tratamiento certeros.

Abstract: BACKGROUND: Phyllodes tumor of the vulva is a rare, benign, proliferative lesion that shares similar characteristics with mammary tumors. It appears as a unilateral, non-painful mass located on the labia majora or majora, and on the posterior fork of the vulva. To date, 30 cases of phyllodes tumor have been reported worldwide. Due to its low incidence, the specific epidemiological and pathophysiological data of the disease have not been estimated. CLINICAL CASE: A 20-year-old patient, who came to the clinic for a vulvar mass of approximately 11 cm in the left, non-painful, rapidly growing lip. Treatment consisted of surgical resection. The presumptive diagnosis was vulvar fibroma. The pathology service reported: a 280 g mass, 12 x 7 x 6 cm, with irregular edges and shapes, multinodular, covered by skin with epidermis; Solid cutting surface with uneven edges, leafy appearance and soft consistency. The diagnosis of low-grade phyllodes (benign) tumor was established. CONCLUSION: The phyllodes tumor of the vulva is an exceptional alteration, so it is important to know its clinical manifestations, in addition to the macro and microscopic characteristics to establish the accurate diagnosis and treatment.

Endometriosis polipoide: una variante de la endometriosis / Polypoid endometriosis: A variant of endometriosis

Resumen: ANTECEDENTES: La endometriosis polipoide describe una variante poco común de la endometriosis, con características histológicas que simulan un pólipo endometrial y posibilidad de transformación maligna. CASO CLÍNICO: Paciente de 46 años, acudió a consulta por dolor abdominal y sangrado uterino anormal. Los estudios de imagen revelaron una masa heterogénea de forma irregular, adyacente al ovario. Los análisis de sangre reportaron concentraciones elevadas de Ca-125 (75.2 U/mL). El tratamiento consistió en resección quirúrgica mediante laparotomía. El reporte de histopatología fue: endometriosis polipoide. Actualmente la paciente permanece en vigilancia médica, sin recidiva de la enfermedad. CONCLUSIONES: La endometriosis polipoide es una variante poco común de la endometriosis, con posibilidad de evolución maligna. Es importante conocer la enfermedad, con la finalidad de ofrecer el tratamiento adecuado.

Abstract: BACKGROUND: Polypoid endometriosis was first introduced in 1980. It was used to describe an uncommon variant of endometriosis with histological features simulating an endometrial polyp and may be at risk of malignant transformation. CLINICAL CASE: A 46-year-old female presented with lower abdominal pain and Abnormal uterine bleeding. Image studies revealed an irregular shaped, heterogeneous mass adjacent to the ovary. Blood tests showed an elevated CA-125 value (75.2 U/ml). Resection of the mass was performed by laparotomy and the definitive study of histopathology revealed polypoid endometriosis. Currently the patient continues in surveillance without disease recurrence. CONCLUSIONS: Polypoid endometriosis is an uncommon variant of endometriosis, with the possibility of malignant evolution. This rare form of disease should be known, in order to provide adequate treatment for the patient.

Voluntary and involuntary contributions to perceptually guided saccadic choices resolved with millisecond precision.

In the antisaccade task, which is considered a sensitive assay of cognitive function, a salient visual cue appears and the participant must look away from it. This requires sensory, motor-planning, and cognitive neural mechanisms, but what are their unique contributions to performance, and when exactly are they engaged? Here, by manipulating task urgency, we generate a psychophysical curve that tracks the evolution of the saccadic choice process with millisecond precision, and resolve the distinct contributions of reflexive (exogenous) and voluntary (endogenous) perceptual mechanisms to antisaccade performance over time. Both progress extremely rapidly, the former driving the eyes toward the cue early on (∼100 ms after cue onset) and the latter directing them away from the cue ∼40 ms later. The behavioral and modeling results provide a detailed, dynamical characterization of attentional and oculomotor capture that is not only qualitatively consistent across participants, but also indicative of their individual perceptual capacities.

All-or-None Context Dependence Delineates Limits of FEF Visual Target Selection.

Choices of where to look are informed by perceptual judgments, which locate objects of current value or interest within the visual scene. This perceptual-motor transform is partly implemented in the frontal eye field (FEF), where visually responsive neurons appear to select behaviorally relevant visual targets and, subsequently, saccade-related neurons select the movements required to look at them. Here, we use urgent decision-making tasks to show (1) that FEF motor activity can direct accurate, visually informed choices in the complete absence of prior target-distracter discrimination by FEF visual responses and (2) that such discrimination by FEF visual cells shows an all-or-none reliance on the presence of stimulus attributes strongly associated with saliency-driven attentional allocation. The present findings suggest that FEF visual target selection is specific to visual judgments made on the basis of saliency and may not play a significant role in guiding saccadic choices informed solely by feature content.

Saccadic inhibition interrupts ongoing oculomotor activity to enable the rapid deployment of alternate movement plans.

Diverse psychophysical and neurophysiological results show that oculomotor networks are continuously active, such that plans for making the next eye movement are always ongoing. So, when new visual information arrives unexpectedly, how are those plans affected? At what point can the new information start guiding an eye movement, and how? Here, based on modeling and simulation results, we make two observations that are relevant to these questions. First, we note that many experiments, including those investigating the phenomenon known as "saccadic inhibition", are consistent with the idea that sudden-onset stimuli briefly interrupt the gradual rise in neural activity associated with the preparation of an impending saccade. And second, we show that this stimulus-driven interruption is functionally adaptive, but only if perception is fast. In that case, putting on hold an ongoing saccade plan toward location A allows the oculomotor system to initiate a concurrent, alternative plan toward location B (where a stimulus just appeared), deliberate (briefly) on the priority of each target, and determine which plan should continue. Based on physiological data, we estimate that the advantage of this strategy, relative to one in which any plan once initiated must be completed, is of several tens of milliseconds per saccade.

Saccade metrics reflect decision-making dynamics during urgent choices.

A perceptual judgment is typically characterized by constructing psychometric and chronometric functions, i.e., by mapping the accuracies and reaction times of motor choices as functions of a sensory stimulus feature dimension. Here, we show that various saccade metrics (e.g., peak velocity) are similarly modulated as functions of sensory cue viewing time during performance of an urgent-decision task. Each of the newly discovered functions reveals the dynamics of the perceptual evaluation process inherent to the underlying judgment. Remarkably, saccade peak velocity correlates with statistical decision confidence, suggesting that saccade kinematics reflect the degree of certainty with which an urgent perceptual decision is made. The data were explained by a race-to-threshold model that also replicates standard performance measures and cortical oculomotor neuronal activity in the task. The results indicate that, although largely stereotyped, saccade metrics carry subtle but reliable traces of the underlying cognitive processes that give rise to each oculomotor choice.

Motor selection dynamics in FEF explain the reaction time variance of saccades to single targets.

In studies of voluntary movement, a most elemental quantity is the reaction time (RT) between the onset of a visual stimulus and a saccade toward it. However, this RT demonstrates extremely high variability which, in spite of extensive research, remains unexplained. It is well established that, when a visual target appears, oculomotor activity gradually builds up until a critical level is reached, at which point a saccade is triggered. Here, based on computational work and single-neuron recordings from monkey frontal eye field (FEF), we show that this rise-to-threshold process starts from a dynamic initial state that already contains other incipient, internally driven motor plans, which compete with the target-driven activity to varying degrees. The ensuing conflict resolution process, which manifests in subtle covariations between baseline activity, build-up rate, and threshold, consists of fundamentally deterministic interactions, and explains the observed RT distributions while invoking only a small amount of intrinsic randomness.

When the simplest voluntary decisions appear patently suboptimal.

Rahnev & Denison (R&D) catalog numerous experiments in which performance deviates, often in subtle ways, from the theoretical ideal. We discuss an extreme case, an elementary behavior (reactive saccades to single targets) for which a simple contextual manipulation results in responses that are dramatically different from those expected based on reward maximization - and yet are highly informative and amenable to mechanistic examination.

Urgent Commitment Issues.

Making a choice requires a combination of urgency, which provides the drive to act, and perceptual analysis, which identifies the most advantageous alternative. In behaving monkeys, Thura and Cisek (2017, in this issue of Neuron) map these processes onto separate brain structures with a complex interplay.

Neural correlates of working memory development in adolescent primates.

Working memory ability matures after puberty, in parallel with structural changes in the prefrontal cortex, but little is known about how changes in prefrontal neuronal activity mediate this cognitive improvement in primates. To address this issue, we compare behavioural performance and neurophysiological activity in monkeys as they transitioned from puberty into adulthood. Here we report that monkeys perform working memory tasks reliably during puberty and show modest improvement in adulthood. The adult prefrontal cortex is characterized by increased activity during the delay period of the task but no change in the representation of stimuli. Activity evoked by distracting stimuli also decreases in the adult prefrontal cortex. The increase in delay period activity relative to the baseline activity of prefrontal neurons is the best correlate of maturation and is not merely a consequence of improved performance. Our results reveal neural correlates of the working memory improvement typical of primate adolescence.

Emergence of an abstract categorical code enabling the discrimination of temporally structured tactile stimuli.

The problem of neural coding in perceptual decision making revolves around two fundamental questions: (i) How are the neural representations of sensory stimuli related to perception, and (ii) what attributes of these neural responses are relevant for downstream networks, and how do they influence decision making? We studied these two questions by recording neurons in primary somatosensory (S1) and dorsal premotor (DPC) cortex while trained monkeys reported whether the temporal pattern structure of two sequential vibrotactile stimuli (of equal mean frequency) was the same or different. We found that S1 neurons coded the temporal patterns in a literal way and only during the stimulation periods and did not reflect the monkeys' decisions. In contrast, DPC neurons coded the stimulus patterns as broader categories and signaled them during the working memory, comparison, and decision periods. These results show that the initial sensory representation is transformed into an intermediate, more abstract categorical code that combines past and present information to ultimately generate a perceptually informed choice.