Biased Competition Research Articles

Neurotranslations: Interpreting the Human Brain’s Attention System

Our ability to think, create, innovate, and communicate—to survive and thrive—depends on the brain’s attention system: from the reticular activation system that triggers the fight-or-flight response to the cortical and subcortical networks managing familiar and unfamiliar stimuli during the creative process, problem solving, decision making, and related functions that involve interrelated affective cognitive processes. The attention system links key networks of the central and peripheral nervous system, enabling us to be conscious and cognizant of the world of information all human systems and our creations depend on. This article addresses a number of key issues and challenges concerning attentional mechanisms, considering how our nervous systems constantly attend to information needed to perform certain actions that keep us alert, alive and well. The author uses three works of fine art that explore the neural mechanisms of attention underlying the creative process. Like noninvasive imaging tools (EEG, fMRI, PET, SPECT, MEG, VEPs) used to illuminate attention and other key brain functions, these purposeful artworks serve a complementary usefulness: interpreting the ways and means by which the brain tunes into or tunes out information in milliseconds, depending on the level of interest in or connection with the information (i.e., its contents) and the circumstances (i.e., contexts) in which one experiences it. The more personally meaningful and relevant the information is, the more attentive we tend to be in remembering and using it. The metaphorical artworks presented for discussion—“Breaking the Mind Barrier” (1985–86), “Prescience, Foresight” (1986–88), and “Grasping Synapses” (2000–04)—interpret attentional mechanisms that enable us to connect with things our minds are drawn to and care to remember. The hypothesis adventured here is that attention, in addition to its rudimentary functions, is intimately involved in making information personally meaningful and relevant to our lives. Without this fundamental sense of relevance, we neither learn nor remember anything beyond first impressions. The author posits that attentional mechanisms compete to process certain information that interests us, and not just because it’s in our frontal eye fields or immediately relevant to the brain part tasked with processing it, as the biased competition theory suggests.

A Method for the Minimization of Competition Bias in Signal Detection from Spontaneous Reporting Databases.

The two methods for minimizing competition bias in signal of disproportionate reporting (SDR) detection--masking factor (MF) and masking ratio (MR)--have focused on the strength of disproportionality for identifying competitors and have been tested using competitors at the drug level. The aim of this study was to develop a method that relies on identifying competitors by considering the proportion of reports of adverse events (AEs) that mention the drug class at an adequate level of drug grouping to increase sensitivity (Se) for SDR unmasking, and its comparison with MF and MR. Reports in the French spontaneous reporting database between 2000 and 2005 were selected. Five AEs were considered: myocardial infarction, pancreatitis, aplastic anemia, convulsions, and gastrointestinal bleeding; related reports were retrieved using standardized Medical Dictionary for Regulatory Activities (MedDRA(®)) queries. Potential competitors of AEs were identified using the developed method, i.e. Competition Index (ComIn), as well as MF and MR. All three methods were tested according to Anatomical Therapeutic Chemical (ATC) classification levels 2-5. For each AE, SDR detection was performed, first in the complete database, and second after removing reports mentioning competitors; SDRs only detected after the removal were unmasked. All unmasked SDRs were validated using the Summary of Product Characteristics, and constituted the reference dataset used for computing the performance for SDR unmasking (area under the curve [AUC], Se). Performance of the ComIn was highest when considering competitors at ATC level 3 (AUC: 62 %; Se: 52 %); similar results were obtained with MF and MR. The ComIn could greatly minimize the competition bias in SDR detection. Further study using a larger dataset is needed.

Peer Review and Surgical Innovation: Robotic Surgery and Its Hurdles.

The peer review processes as outlined in the Health Care Quality Improvement Act (HCQIA) is meant ensure quality standard of care through a self-policing mechanism by the medical community. This process grants immunity for people filing a peer review, which is meant to protect whistleblowers. However, it also creates a loophole that can be used maliciously to hinder competition. This is accentuated when surgeons are integrating new technologies, such as robotic surgery, into their practice. With more than 2000 da Vinci robots in use and more than 300 new units being shipped each year, robotic surgery has become a mainstay in the surgical field. The applications for robots continue to expand as surgeons discover their expanding capability. We need a better peer review process. That ensures the peer review is void of competitive bias. Peer reviewers need to be familiar with the procedure and the technology. The current process could stymie innovation in the name of competition.

Separating Visual and Motor Components of Motor Cortex Activation for Multiple Reach Targets: A Visuomotor Adaptation Study.

There is growing evidence that the motor cortex routinely prepares for different movements simultaneously, each suited to a possible course of events in the immediate environment. The preparatory motor cortex activity for different movements can be seen as a competition between groups of neurons. This competition is influenced by how similar the alternative movements are; for example, in terms of direction, determined by the proximity of alternative movement goals. This study investigates whether the proximity of alternative reach goals has a direct influence on motor cortex activity (in the form of brain oscillations) or if it has an effect only through conscious evaluation of the separation between targets. We establish that there is a direct effect, supporting the biased competition model of action selection.

The snooze of lose: Rapid reaching reveals that losses are processed more slowly than gains.

Decision making revolves around weighing potential gains and losses. Research in economic decision making has emphasized that humans exercise disproportionate caution when making explicit choices involving loss. By comparison, research in perceptual decision making has revealed a processing advantage for targets associated with potential gain, though the effects of loss have been explored less systematically. Here, we use a rapid reaching task to measure the relative sensitivity (Experiment 1) and the time course (Experiments 2 and 3) of rapid actions with regard to the reward valence and probability of targets. We show that targets linked to a high probability of gain influence actions about 100 ms earlier than targets associated with equivalent probability and value of loss. These findings are well accounted for by a model of stimulus response in which reward modulates the late, postpeak phase of the activity. We interpret our results within a neural framework of biased competition that is resolved in spatial maps of behavioral relevance. As implied by our model, all visual stimuli initially receive positive activation. Gain stimuli can build off of this initial activation when selected as a target, whereas loss stimuli have to overcome this initial activation in order to be avoided, accounting for the observed delay between valences. Our results bring clarity to the perceptual effects of losses versus gains and highlight the importance of considering the timeline of different biasing factors that influence decisions.

Neuro-oscillatory mechanisms of intersensory selective attention and task switching in school-aged children, adolescents and young adults.

The ability to attend to one among multiple sources of information is central to everyday functioning. Just as central is the ability to switch attention among competing inputs as the task at hand changes. Such processes develop surprisingly slowly, such that even into adolescence, we remain slower and more error prone at switching among tasks compared to young adults. The amplitude of oscillations in the alpha band (~8-14Hz) tracks the top-down deployment of attention, and there is growing evidence that alpha can act as a suppressive mechanism to bias attention away from distracting sensory input. Moreover, the amplitude of alpha has also been shown to be sensitive to the demands of switching tasks. To understand the neural basis of protracted development of these executive functions, we recorded high-density electrophysiology from school-aged children (8-12years), adolescents (13-17), and young adults (18-34) as they performed a cued inter-sensory selective attention task. The youngest participants showed increased susceptibility to distracting inputs that was especially evident when switching tasks. Concordantly, they showed weaker and delayed onset of alpha modulation compared to the older groups. Thus the flexible and efficient deployment of alpha to bias competition among attentional sets remains underdeveloped in school-aged children.

A model for attentional information routing through coherence predicts biased competition and multistable perception.

Selective attention allows to focus on relevant information and to ignore distracting features of a visual scene. These principles of information processing are reflected in response properties of neurons in visual area V4: if a neuron is presented with two stimuli in its receptive field, and one is attended, it responds as if the nonattended stimulus was absent (biased competition). In addition, when the luminance of the two stimuli is temporally and independently varied, local field potentials are correlated with the modulation of the attended stimulus and not, or much less, correlated with the nonattended stimulus (information routing). To explain these results in one coherent framework, we present a two-layer spiking cortical network model with distance-dependent lateral connectivity and converging feed-forward connections. With oscillations arising inherently from the network structure, our model reproduces both experimental observations. Hereby, lateral interactions and shifts of relative phases between sending and receiving layers (communication through coherence) are identified as the main mechanisms underlying both biased competition as well as selective routing. Exploring the parameter space, we show that the effects are robust and prevalent over a broad range of parameters. In addition, we identify the strength of lateral inhibition in the first model layer as crucial for determining the working regime of the system: increasing lateral inhibition allows a transition from a network configuration with mixed representations to one with bistable representations of the competing stimuli. The latter is discussed as a possible neural correlate of multistable perception phenomena such as binocular rivalry.

The Competitive Influences of Perceptual Load and Working Memory Guidance on Selective Attention.

The perceptual load theory in selective attention literature proposes that the interference from task-irrelevant distractor is eliminated when perceptual capacity is fully consumed by task-relevant information. However, the biased competition model suggests that the contents of working memory (WM) can guide attentional selection automatically, even when this guidance is detrimental to visual search. An intriguing but unsolved question is what will happen when selective attention is influenced by both perceptual load and WM guidance. To study this issue, behavioral performances and event-related potentials (ERPs) were recorded when participants were presented with a cue to either identify or hold in memory and had to perform a visual search task subsequently, under conditions of low or high perceptual load. Behavioural data showed that high perceptual load eliminated the attentional capture by WM. The ERP results revealed an obvious WM guidance effect in P1 component with invalid trials eliciting larger P1 than neutral trials, regardless of the level of perceptual load. The interaction between perceptual load and WM guidance was significant for the posterior N1 component. The memory guidance effect on N1 was eliminated by high perceptual load. Standardized Low Resolution Electrical Tomography Analysis (sLORETA) showed that the WM guidance effect and the perceptual load effect on attention can be localized into the occipital area and parietal lobe, respectively. Merely identifying the cue produced no effect on the P1 or N1 component. These results suggest that in selective attention, the information held in WM could capture attention at the early stage of visual processing in the occipital cortex. Interestingly, this initial capture of attention by WM could be modulated by the level of perceptual load and the parietal lobe mediates target selection at the discrimination stage.

The Commingled Division of Visual Attention.

Many critical activities require visual attention to be distributed simultaneously among distinct tasks where the attended foci are not spatially separated. In our two experiments, participants performed a large number of trials where both a primary task (enumeration of spots) and a secondary task (reporting the presence/absence or identity of a distinctive shape) required the division of visual attention. The spots and the shape were commingled spatially and the shape appeared unpredictably on a relatively small fraction of the trials. The secondary task stimulus (the shape) was reported in inverse proportion to the attentional load imposed by the primary task (enumeration of spots). When the shape did appear, performance on the primary task (enumeration) suffered relative to when the shape was absent; both speed and accuracy were compromised. When the secondary task required identification in addition to detection, reaction times increased by about 200 percent. These results are broadly compatible with biased competition models of perceptual processing. An important area of application, where the commingled division of visual attention is required, is the augmented reality head-up display (AR-HUD). This innovation has the potential to make operating vehicles safer but our data suggest that there are significant concerns regarding driver distraction.

Liver injury with novel oral anticoagulants: assessing post-marketing reports in the US Food and Drug Administration adverse event reporting system.

We assessed the hepatic safety of novel oral anticoagulants (NOACs) analyzing the publicly available US-FDA adverse event reporting system (FAERS). We extracted reports of drug-induced liver injury (DILI) associated with NOACs, including acute liver failure (ALF) events. Based on US marketing authorizations, we performed disproportionality analyses, calculating reporting odds ratios (RORs) with 95% confidence interval (CI), also to test for event- and drug-related competition bias, and case-by-case evaluation for concomitant medications. DILI reports represented 3.7% (n = 146) and 1.7% (n = 222) of all reports for rivaroxaban and dabigatran, respectively. No statistically significant association was found for dabigatran, in primary and secondary analyses. Disproportionality signals emerged for rivaroxaban in primary analysis (ALF: n = 25, ROR = 2.08, 95% CI 1.34, 3.08). In a large proportion of DILI reports concomitant hepatotoxic and/or interacting drugs were recorded: 42% and 37% (rivaroxaban and dabigatran, respectively), especially statins, paracetamol and amiodarone. Among ALF reports, fatal outcome occurred in 49% of cases (44% and 51%, rivaroxaban and dabigatran, respectively), whereas rapid onset of the event (<1 week) was detected in 46% of patients (47% and 44%, respectively). The disproportionality signal for rivaroxaban calls for further comparative population-based studies to characterize and quantify the actual DILI risk of NOACs, taking into account drug- and patient-related risk factors. As DILI is unpredictable, our findings strengthen the role of (a) timely pharmacovigilance to detect post-marketing signals of DILI through FAERS and other data sources, (b) clinicians to assess early, on a case-by-case basis, the potential responsibility of NOACs when they diagnose a liver injury.

A mechanistic cortical microcircuit of attention for amplification, normalization and suppression

Computational models of visual attention have replicated a large number of data from visual attention experiments. However, typically each computational model has been shown to account for only a few data sets. We developed a novel model of attention, particularly focused on explaining single cell recordings in multiple brain areas, to better understand the underlying computational circuits of attention involved in spatial- and feature-based biased competition, modulation of the contrast response function, modulation of the neuronal tuning curve, and modulation of surround suppression. In contrast to previous models, we use a two layer structure inspired by the layered cortical architecture which implements amplification, divisive normalization and suppression as well as spatial pooling.

A biased competition theory of cytotoxic T lymphocyte interaction with tumor nodules.

The dynamics of the interaction between Cytotoxic T Lymphocytes (CTL) and tumor cells has been addressed in depth, in particular using numerical simulations. However, stochastic mathematical models that take into account the competitive interaction between CTL and tumors undergoing immunoediting, a process of tumor cell escape from immunesurveillance, are presently missing. Here, we introduce a stochastic dynamical particle interaction model based on experimentally measured parameters that allows to describe CTL function during immunoediting. The model describes the competitive interaction between CTL and melanoma cell nodules and allows temporal and two-dimensional spatial progression. The model is designed to provide probabilistic estimates of tumor eradication through numerical simulations in which tunable parameters influencing CTL efficacy against a tumor nodule undergoing immunoediting are tested. Our model shows that the rate of CTL/tumor nodule productive collisions during the initial time of interaction determines the success of CTL in tumor eradication. It allows efficient cytotoxic function before the tumor cells acquire a substantial resistance to CTL attack, due to mutations stochastically occurring during cell division. Interestingly, a bias in CTL motility inducing a progressive attraction towards a few scout CTL, which have detected the nodule enhances early productive collisions and tumor eradication. Taken together, our results are compatible with a biased competition theory of CTL function in which CTL efficacy against a tumor nodule undergoing immunoediting is strongly dependent on guidance of CTL trajectories by scout siblings. They highlight unprecedented aspects of immune cell behavior that might inspire new CTL-based therapeutic strategies against tumors.

A distributed network critical for selecting among tool-directed actions

Tools pose a challenge to the need to select actions appropriate for task goals and environmental constraints. For many tools (e.g., calculator), actions for “using” and “grasping-to-move” conflict with each other and may compete during selection. To date, little is known about the mechanisms that enable selection between possible tool actions or their neural substrates. The study of patients with chronic left hemisphere stroke, many of whom are deficient in tool-use action (apraxic), provides an opportunity to elucidate these issues. Here, 31 such patients pantomimed or recognized tool use actions for “conflict” and “non-conflict” tools. Voxel-based lesion-symptom mapping (VLSM), lesion subtraction, and tractographic overlap analyses were used to determine brain regions necessary for selecting among tool-directed actions. Lesions to posterior middle temporal gyrus (pMTG) and anterior intraparietal sulcus (aIPS) tended to impair production of use actions similarly for both conflict and non-conflict tools. By contrast, lesions to the supramarginal gyrus (SMG), inferior frontal gyrus (IFG)/anterior insula, and superior longitudinal fasciculus (SLF) specifically impaired production of use actions for conflict tools. Patients' errors on conflict tools suggested inappropriate selection of grasping actions and difficulty selecting single actions. Use/grasp conflict had no effect on action recognition. We suggest that the SMG/SLF/IFG pathway implements biased competition between possible tool actions, while aIPS and pMTG compute the structure-based and skilled use actions, respectively, that constitute input to this competitive process. This is the first study to demonstrate a reliable link between a characteristic of single tools (i.e., their association with different use and grasp actions) and action selection difficulties. Additionally, the data allow us to posit an SMG-involved subtype of apraxia characterized by an inability to resolve action competition.

Attentional guidance by the contents of working memory and the N2PC component

Abstract The Biased Competition Model suggests that stimuli matching the contents of working memory increase the likelihood that memory-matching items will be attended. According to this account, the representations in working memory create an involuntary capture of attention toward memory-matching items in the visual field. This influential assumption proposed by the biased competition model has been explored in a number of studies, showing that the contents of working memory exert an automatic bias in favor of memory matching items. These studies showed that active maintenance of objects in working memory automatically shift attention toward the memory matching-object and produce a negative early lateralized event related potential (ERP), the N2pc, toward the side of visual field where the memorized item appeared. This component, the N2pc is an important tool to investigate the allocation of attention by working memory representations, especially for the activity the activity that is specific to the hemisphere which is contralateral with respect to the hemifield containing e.g. the to-be-remembered items could be measured. This characteristic of the N2pc facilitates measuring the general direction of attention with fine-grained temporal resolution. Therefore, the N2pc could be used as an index to describe the lateralization effect of memorized items on attention related studies.

Recent developments in a computational theory of visual attention (TVA)

This article reviews the foundations of the theory of visual attention (TVA) and describes recent developments in the theory. TVA is based on the principle of biased competition: All possible visual categorizations ascribing features to objects compete (race) to become encoded into visual short-term memory before it is filled up. Each of the possible categorizations is supported by sensory evidence, but the competition is biased by multiplication with attentional weights (high weights on important objects) and perceptual biases (toward use of important categories). The way sensory evidence and attentional biases interact is specified in the rate and weight equations of TVA, so TVA represents a mathematical formalization of the biased competition principle. In addition to describing TVA as a psychological theory, we present the neural interpretation of TVA, NTVA.

The temporal dynamics of visual working memory guidance of selective attention.

The biased competition model proposes that there is top-down directing of attention to a stimulus matching the contents of working memory (WM), even when the maintenance of a WM representation is detrimental to target relevant performance. Despite many studies elucidating that spatial WM guidance can be present early in the visual processing system, whether visual WM guidance also influences perceptual selection remains poorly understood. Here, we investigated the electrophysiological correlates of early guidance of attention by WM in humans. Participants were required to perform a visual search task while concurrently maintaining object representations in their visual WM. Behavioral results showed that response times (RTs) were longer when the distractor in the visual search task was held in WM. The earliest WM guidance effect was observed in the P1 component (90–130 ms), with match trials eliciting larger P1 amplitude than mismatch trials. A similar result was also found in the N1 component (160–200 ms). These P1 and N1 effects could not be attributed to bottom-up perceptual priming from the presentation of a memory cue, because there was no significant difference in early event-related potential (ERP) component when the cue was merely perceptually identified but not actively held in WM. Standardized Low Resolution Electrical Tomography Analysis (sLORETA) showed that the early WM guidance occurred in the occipital lobe and the N1-related activation occurred in the parietal gyrus. Time-frequency data suggested that alpha-band event-related spectral perturbation (ERSP) magnitudes increased under the match condition compared with the mismatch condition only when the cue was held in WM. In conclusion, the present study suggests that the reappearance of a stimulus held in WM enhanced activity in the occipital area. Subsequently, this initial capture of attention by WM could be inhibited by competing visual inputs through attention re-orientation, reflecting by the alpha-band rhythm.

Descending Control of Neural Bias and Selectivity in a Spatial Attention Network: Rules and Mechanisms

The brain integrates stimulus-driven (exogenous) activity with internally generated (endogenous) activity to compute the highest priority stimulus for gaze and attention. Little is known about how this computation is accomplished neurally. We explored the underlying functional logic in a critical component of the spatial attention network, the optic tectum (OT, superior colliculus in mammals), in awake barn owls. We found that space-specific endogenous influences, evoked by activating descending forebrain pathways, bias competition among exogenous influences, and substantially enhance the quality of the categorical neural pointer to the highest priority stimulus. These endogenous influences operate across sensory modalities. Biologically grounded modeling revealed that the observed effects on network bias and selectivity require a simple circuit mechanism: endogenously driven gain modulation of feedback inhibition among competing channels. Our findings reveal fundamental principles by which internal and external information combine to guide selection of the next target for gaze and attention.

Improving Deaf Children’s Working Memory through Training

The aim of this study was to design and to assess the effectiveness of a working memory (WM) intervention for deaf children. A review of factors that explain deaf students’ poor results in WM tasks was used to identify deaf participants' strengths and difficulties in WM tasks. This review formed the basis for the design of the WM training program assessed in the study. Participants were 77 children in a comparison group and 73 in an intervention group, with the mean age of 8y5m at the start of the program. The participants' severity of hearing loss was at least moderate; approximately 68% of the children had one cochlear implant and the rest had hearing aids only. The design was quasi-experimental: teachers rather than children were assigned either to the comparison or the intervention group. The children were pre- and post-tested in three WM tasks; the regression factor score was used as the measure of their WM. The intervention was implemented by the teachers and comprised two types of games: teacher led games, during which the teachers taught the children rehearsal strategies that combined linguistic and visual-spatial encoding, and web-based games, which the children played without a tutor and involved biased competition with the aim of developing attention control. An analysis of covariance (controlling for pre-test WM scores, age, cognitive ability and pre- to post-test interval) showed that the intervention group differed significantly from the comparison group at post-test; Cohen's d effect size was 0.78. We conclude that it is possible to improve deaf children's performance in WM measures by training that targets their attention problems and teaches them rehearsal strategies.

The effect of biased competition within sequential displays on visual short-term memory

The effect of biased competition within sequential displays on visual short-term memory

Basolateral junction proteins regulate competition for the follicle stem cell niche in the Drosophila ovary.

Epithelial stem cells are routinely lost or damaged during adult life and must therefore be replaced to maintain homeostasis. Recent studies indicate that stem cell replacement occurs through neutral competition in many types of epithelial tissues, but little is known about the factors that determine competitive outcome. The epithelial follicle stem cells (FSCs) in the Drosophila ovary are regularly lost and replaced during normal homeostasis, and we show that FSC replacement conforms to a model of neutral competition. In addition, we found that FSCs mutant for the basolateral junction genes, lethal giant larvae (lgl) or discs large (dlg), undergo a biased competition for niche occupancy characterized by increased invasion of neighboring FSCs and reduced loss. Interestingly, FSCs mutant for a third basolateral junction gene, scribble (scrib), do not exhibit biased competition, suggesting that Lgl and Dlg regulate niche competition through a Scrib-independent process. Lastly, we found that FSCs have a unique cell polarity characterized by broadly distributed adherens junctions and the lack of a mature apical domain. Collectively, these observations indicate that Lgl and Dlg promote the differentiation of FSC progeny to a state in which they are less prone to invade the neighboring niche. In addition, we demonstrate that the neutral drift model can be adapted to quantify non-neutral behavior of mutant clones.