Perfil cognitivo en el Mareo Perceptual Postural Persistente: Implicancias sobre su fisiopatología como disfunción cognitiva viso-vestibular superior

Introducción: El mareo perceptual postural persistente (MPPP) es, probablemente, la causa más prevalente de mareo crónico. Sin embargo, su fisiopatología es aún motivo de duda y debate. En el presente artículo, proponemos que el MPPP se caracteriza por disfunciones cognitivas de orden superior, al punto de diferenciarse en estas dimensiones de controles sanos y pacientes con patologías vestibulares no-MPPP. Objetivo: Determinar si pacientes con MPPP presentan alteraciones discriminantes respecto a grupos controles, en ámbitos de atención, memoria de trabajo visoespacial, planificación espacial, funciones ejecutivas y rendimiento cognitivo global. Material y Método: Estudio descriptivo transversal con sujetos de entre 18 y 65 años, reclutados de una unidad de otoneurología ambulatoria. Se aplicaron pruebas Montreal Cognitive Assessment (MoCA), tarea de retención de dígitos, Trail Making Test, Corsi Block-Tapping Task y Torre de Londres. Resultados: 30 pacientes fueron categorizados en tres grupos: grupo MPPP (n = 14), grupo vestibular no-MPPP (n = 11) y grupo control (n = 5). El grupo MPPP exhibió un rendimiento significativamente inferior en pruebas de planificación, velocidad de procesamiento y funciones ejecutivas en ámbitos visoespaciales, mientras que en atención y memoria visoespacial no hubo diferencias entre grupos. Conclusión: El MPPP podría caracterizarse por una disfunción de procesos cognitivos superiores de construcción espacial de mayor complejidad, respetando funciones visoespaciales de menor orden como la memoria de trabajo. Estos hallazgos ofrecen nuevas luces para comprender la fisiopatología del MPPP y sus implicancias clínicas.

Introduction: Persistent postural-perceptual dizziness (PPPD) is probably the most prevalent cause of chronic dizziness. However, its pathophysiology is still a matter of uncertainty and debate. In this article, we propose that PPPD is characterized by higher-order cognitive dysfunctions, to the point of differentiating it from healthy controls and patients with non-PPPD vestibular pathologies. Aim: To determine whether patients with PPPD exhibit discriminant alterations compared to control groups in the areas of attention, visuospatial working memory, spatial planning, executive functions, and global cognitive performance. Materials and Methods: A cross-sectional descriptive study was conducted with subjects between the ages of 18 and 65 years, recruited from an outpatient otoneurology unit. Tests included the Montreal Cognitive Assessment (MoCA), digit retention task, Trail Making Test, Corsi Block-Tapping Task, and the Tower of London. Results: 30 patients were categorized into three groups: PPPD group (n = 14), non-PPPD vestibular group (n = 11), and control group (n = 5). The PPPD group showed significantly lower performance on tests of planning, processing speed, and executive function in visuospatial domains, while there were no differences between groups in attention and visuospatial memory. Conclusion: PPPD may be characterized by dysfunction of higher-order cognitive processes related to spatial construction of greater complexity, while sparing lower-order visuospatial functions such as working memory. These findings offer new insights into the pathophysiology of PPPD and its clinical implications.

Another in need enhances prosociality and modulates frontal theta oscillations in young adults.

Introduction: Decision-making is a process that can be strongly affected by social factors. Evidence has shown how people deviate from traditional rational-choice predictions under different levels of social interactions. The emergence of prosocial decision-making, defined as any action that is addressed to benefit another individual even at the expense of personal benefits, has been reported as an example of such social influence. Furthermore, brain evidence has shown the involvement of structures such as the prefrontal cortex, anterior insula, and midcingulate cortex during decision settings in which a decision maker interacts with others under physical pain or distress or while being observed by others. Methods: Using a slightly modified version of the dictator game and EEG recordings, we tested the hypothesis that the inclusion of another person into the decision setting increases prosocial decisions in young adults and that this increase is higher when the other person is associated with others in need. At the brain level, we hypothesized that the increase in prosocial decisions correlates with frontal theta activity. Results and Discussion: The results showed that including another person in the decision, setting increased prosocial behavior only when this presence was associated with someone in need. This effect was associated with an increase in frontocentral theta-oscillatory activity. These results suggest that the presence of someone in need enhances empathy concerns and norm compliance, raising the participants' prosocial decision-making.

Functional Dizziness as a Spatial Cognitive Dysfunction.

(1) Background: Persistent postural-perceptual dizziness (PPPD) is a common chronic dizziness disorder with an unclear pathophysiology. It is hypothesized that PPPD may involve disrupted spatial cognition processes as a core feature. (2) Methods: A cohort of 19 PPPD patients underwent psycho-cognitive testing, including assessments for anxiety, depression, memory, attention, planning, and executive functions, with an emphasis on spatial navigation via a virtual Morris water maze. These patients were compared with 12 healthy controls and 20 individuals with other vestibular disorders but without PPPD. Vestibular function was evaluated using video head impulse testing and vestibular evoked myogenic potentials, while brain magnetic resonance imaging was used to exclude confounding pathology. (3) Results: PPPD patients demonstrated unique impairments in allocentric spatial navigation (as evidenced by the virtual Morris water maze) and in other high-demand visuospatial cognitive tasks that involve executive functions and planning, such as the Towers of London and Trail Making B tests. A factor analysis highlighted spatial navigation and advanced visuospatial functions as being central to PPPD, with a strong correlation to symptom severity. (4) Conclusions: PPPD may broadly impair higher cognitive functions, especially in spatial cognition. We discuss a disruption in the creation of enriched cognitive spatial maps as a possible pathophysiology for PPPD.

Lateral Prefrontal Theta Oscillations Reflect Proactive Cognitive Control Impairment in Males With Attention Deficit Hyperactivity Disorder.

Attention Deficit Hyperactivity Disorder (ADHD) is a common neuropsychiatric disorder in which children present prefrontal cortex (PFC) related functions deficit. Proactive cognitive control is a process that anticipates the requirement of cognitive control and crucially depends on the maturity of the PFC. Since this process is important to ADHD symptomatology, we here test the hypothesis that children with ADHD have proactive cognitive control impairments and that these impairments are reflected in the PFC oscillatory activity. We recorded EEG signals from 29 male children with ADHD and 25 typically developing (TD) male children while they performed a Go-Nogo task, where the likelihood of a Nogo stimulus increased while a sequence of consecutive Go stimuli elapsed. TD children showed proactive cognitive control by increasing their reaction time (RT) concerning the number of preceding Go stimuli, whereas children with ADHD did not. This adaptation was related to modulations in both P3a potential and lateral prefrontal theta oscillation for TD children. Children with ADHD as a group did not demonstrate either P3a or theta modulation. But, individual variation in theta activity was correlated with the ADHD symptomatology. The results depict a neurobiological mechanism of proactive cognitive control impairments in children with ADHD.

Neural markers of social and monetary rewards in children with Attention-Deficit/Hyperactivity Disorder and Autism Spectrum Disorder.

Recent theories of decision making propose a shared value-related brain mechanism for encoding monetary and social rewards. We tested this model in children with Attention-Deficit/Hyperactivity Disorder (ADHD), children with Autism Spectrum Disorder (ASD) and control children. We monitored participants' brain dynamics using high density-electroencephalography while they played a monetary and social reward tasks. Control children exhibited a feedback Error-Related Negativity (fERN) modulation and Anterior Cingulate Cortex (ACC) source activation during both tasks. Remarkably, although cooperation resulted in greater losses for the participants, the betrayal options generated greater fERN responses. ADHD subjects exhibited an absence of fERN modulation and reduced ACC activation during both tasks. ASD subjects exhibited normal fERN modulation during monetary choices and inverted fERN/ACC responses in social options than did controls. These results suggest that in neurotypicals, monetary losses and observed disloyal social decisions induced similar activity in the brain value system. In ADHD children, difficulties in reward processing affected early brain signatures of monetary and social decisions. Conversely, ASD children showed intact neural markers of value-related monetary mechanisms, but no brain modulation by prosociality in the social task. These results offer insight into the typical and atypical developments of neural correlates of monetary and social reward processing.

Stochastic model predicts evolving preferences in the Iowa gambling task.

Learning under uncertainty is a common task that people face in their daily life. This process relies on the cognitive ability to adjust behavior to environmental demands. Although the biological underpinnings of those cognitive processes have been extensively studied, there has been little work in formal models seeking to capture the fundamental dynamic of learning under uncertainty. In the present work, we aimed to understand the basic cognitive mechanisms of outcome processing involved in decisions under uncertainty and to evaluate the relevance of previous experiences in enhancing learning processes within such uncertain context. We propose a formal model that emulates the behavior of people playing a well established paradigm (Iowa Gambling Task - IGT) and compare its outcome with a behavioral experiment. We further explored whether it was possible to emulate maladaptive behavior observed in clinical samples by modifying the model parameter which controls the update of expected outcomes distributions. Results showed that the performance of the model resembles the observed participant performance as well as IGT performance by healthy subjects described in the literature. Interestingly, the model converges faster than some subjects on the decks with higher net expected outcome. Furthermore, the modified version of the model replicated the trend observed in clinical samples performing the task. We argue that the basic cognitive component underlying learning under uncertainty can be represented as a differential equation that considers the outcomes of previous decisions for guiding the agent to an adaptive strategy.

Pupil dilation signals uncertainty and surprise in a learning gambling task.

Pupil dilation under constant illumination is a physiological marker where modulation is related to several cognitive functions involved in daily decision making. There is evidence for a role of pupil dilation change during decision-making tasks associated with uncertainty, reward-prediction errors and surprise. However, while some work suggests that pupil dilation is mainly modulated by reward predictions, others point out that this marker is related to uncertainty signaling and surprise. Supporting the latter hypothesis, the neural substrate of this marker is related to noradrenaline (NA) activity which has been also related to uncertainty signaling. In this work we aimed to test whether pupil dilation is a marker for uncertainty and surprise in a learning task. We recorded pupil dilation responses in 10 participants performing the Iowa Gambling Task (IGT), a decision-making task that requires learning and constant monitoring of outcomes' feedback, which are important variables within the traditional study of human decision making. Results showed that pupil dilation changes were modulated by learned uncertainty and surprise regardless of feedback magnitudes. Interestingly, greater pupil dilation changes were found during positive feedback (PF) presentation when there was lower uncertainty about a future negative feedback (NF); and by surprise during NF presentation. These results support the hypothesis that pupil dilation is a marker of learned uncertainty, and may be used as a marker of NA activity facing unfamiliar situations in humans.

Potenciales cerebrales relacionados a feedback en el estudio del aprendizaje y la toma de decisiones económicas / Brain Potentials Related to Feedback on the Study of Learning and Economic Decision Making

Investigaciones con Potenciales Relacionados a Eventos han demostrado la existencia de un componente llamado Negatividad Relacionada a Retroalimentación de Error, el cual ha sido referido como una deflexión negativa que distingue entre ganancias y pérdidas, en tanto resultados esperados y no esperados respectivamente. Así, mientras algunos estudios han operacionalizado la idea de resultado esperado como la probabilidad de ganar vs. Perder, otros lo han hecho como la magnitud esperada de las recompensas. Hasta ahora existe poca investigación tendiente a observar cómo estas interpretaciones alternativas de "resultado esperado", o su interacción en términos de un modelo de "valor esperado" que las integre, afectan la Negatividad Relacionada a Retroalimentación de Error. El presente trabajo contextualiza el estudio de los mecanismos cerebrales asociados a la toma de decisiones, situando los estudios de Negatividad Relacionada a Retroalimentación de Error en su contexto teórico, revisa las dos tendencias de estudio desarrolladas hasta la fecha y explora posibilidades de ampliación del estudio de este componente en el contexto del naciente campo transdisciplinario de la neuroeconomía.

Studies using Event-Related Potentials have shown the existence of a component called Feedback Error-Related Negativity (fERN). This component has been characterized as a negative deflection which responds differentially to profits and losses in terms of expected and unexpected outcomes. Thus, while some studies have defined the idea of "expected outcome" as the probability to win vs. to lose, others have defined it as the expected size of rewards. How these alternative interpretations of "expected outcome" affect the fERN's research, and the effects of their interaction under a specific model of "expected value" has not been properly assessed. This work contextualizes the general study of neural mechanisms involved in decisionmaking processes, putting the fERN studies in context; besides, it reviews the two main approaches to its research; and finally, it explores the possibilities to further expand the fERN studies, in the context of the transdisciplinary rising field of neuroeconomics.