Mes: junio 2015

Although motor-language coupling is now being extensively studied, its underlying mechanisms are not fully understood. In this sense, a crucial opposition has emerged between the non-representational and the representational views of embodiment. The former posits that action language is grounded on the non-brain motor system directly engaged by musculoskeletal activity – i.e., peripheral involvement of ongoing actions. Conversely, the latter proposes that such grounding is afforded by the brain´s motor system – i.e., activation of neural areas representing motor action. We addressed this controversy through the action-sentence compatibility effect (ACE) paradigm, which induces a contextual coupling of motor actions and verbal processing. ACEs were measured in three patient groups – early Parkinson´s disease (EPD), neuromyelitis optica (NMO), and acute transverse myelitis (ATM) patients – as well as their respective healthy controls. NMO and ATM constitute models of injury to non-brain motor areas and the peripheral motor system, whereas EPD provides a model of brain motor system impairment. In our study, EPD patients exhibited impaired ACE and verbal processing relative to healthy participants, NMO, and ATM patients. These results indicate that the processing of action-related words is mainly subserved by a cortico-subcortical motor network system, thus supporting a brain-based embodied view on action language. More generally, our findings are consistent with contemporary perspectives for which action/verb processing depends on distributed brain networks supporting context-sensitive motor-language coupling.

Traditionally, Huntington´s disease (HD) has been known as a movement disorder, characterized by motor, psychiatric, and cognitive impairments. Recent studies have shown that motor and action–language processes are neurally associated. The cognitive mechanisms underlying this interaction have been investigated through the action compatibility effect (ACE) paradigm, which induces a contextual coupling of ongoing motor actions and verbal processing. The present study is the first to use the ACE paradigm to evaluate action–word processing in HD patients (HDP) and their families. Specifically, we tested three groups: HDP, healthy first-degree relatives (HDR), and non-relative healthy controls. The results showed that ACE was abolished in HDP as well as HDR, but not in controls. Furthermore, we found that the processing deficits were primarily linguistic, given that they did not correlate executive function measurements. Our overall results underscore the role of cortico-basal ganglia circuits in action–word processing and indicate that the ACE task is a sensitive and robust early biomarker of HD and familial vulnerability.

This Research Topic features several papers tapping the situated nature of emotion and social cognition processes. The volume covers a broad scope of methodologies [behavioral assessment, functional magnetic resonance imaging (fMRI), structural neuroimaging, event-related potentials (ERPs), brain connectivity, and peripheral measures], populations (non-human animals, neurotypical participants, developmental studies, and neuropsychiatric and pathological conditions), and article types (original research, review papers, and opinion articles). Through this wide-ranging proposal, we introduce a fresh approach to the study of contextual effects in emotion and social cognition domains. We report four levels of evidence. First, we present studies examining how cognitive and neural functions are influenced by basic affective processes (interoception, motivation and reward, emotional impulsiveness, and appraisal of violent stimuli). A second set of behavioral and neuroscientific studies addresses how performance is modulated by different emotional variables (categorical and dimensional approaches to emotion, language-as-context for emotion, emotional suppression of the attentional blink, and reappraisal effects on the up-regulation of emotions). The studies in our third selection deal with different influences in social cognition (SC) domains (human and non-human comparative studies, long-term effects of social and physical stress, developmental theory of mind, neural bases of passionate love for others, social decision making in normal and psychopathic participants, and frontal lobe contributions to psychosocial adaptation models). Finally, the fourth set of papers investigates the blending of social and emotion-related processes (valence and social salience in amygdala networks, emotional contributions to identification of genuine and faked social expressions, emotional predispositions and social decision making bias, valence of fairness and social decisions, structural neuroimaging of emotional and social impairments in neurodegenerative diseases, and subjective reactivity to emotional stimuli and their association with moral cognition). A brief summary of all these studies is offered in the following sections.

Previous studies about personality changes in dementia suggest that they may be due to the disruption of the biological basis of personality traits, and hence, that they are disease specific and universal. However, evidence about its specificity is still limited and scarce regarding culturally diverse populations. Accordingly, our aim was to compare personality changes in Argentinean patients with Alzheimer disease, behavioral variant of frontotemporal dementia, and primary progressive aphasia. The closest living relatives of patients diagnosed with Alzheimer disease (n=19), behavioral variant of frontotemporal dementia (n=16), and primary progressive aphasia (n=15) were asked to complete 2 versions of the personality inventory NEO Personality Inventory-Revised, one for assessing patients’ premorbid personality traits, and the other for assessing current traits. All groups showed changes in several domains and facets of the NEO Personality Inventory-Revised. Globally, the observed pattern of changes was fairly consistent with previous studies based on the same model of personality. Nevertheless, our results regarding disease-specificity were less conclusive. Even if there were some indicators of specific differences between groups, most traits varied similarly across the 3 groups, revealing a pattern of generalized changes in personality expression after illness onset. More studies are needed that help to distinguish real personality changes from other affective or cognitive symptoms that accompany dementia, as well as further data from culturally diverse populations.

Previous single-case reports in Posterior Cortical Atrophy (PCA) have shown preserved non-conscious visual recognition despite the absence of explicit recognition. In this study we investigated three levels of visual recognition in both a female patient with PCA and a control group during the presentation of neutral, positive, and negative affective stimuli. Our results confirmed the profile of impaired explicit recognition and intact psychophysiological responses in the patient. In addition, she was able to implicitly recognize the valence and intensity of arousal of these stimuli. We suggest that implicit emotional awareness may mediates explicit and psychophysiological recognition in PCA.

Predictive theories of action observation propose that we use our own motor system as a guide for anticipating and understanding other people‟s actions through the generation of context-based expectations. According to this view, people should be better in predicting and interpreting those actions that are present in their own motor repertoire compared to those that are not. We recorded high-density event-related potentials (ERPs: P300, N400 and Slow Wave, SW) and source estimation in 80 subjects separated by their level of expertise (experts, beginners and naïves) as they observed realistic videos of Tango steps with different degrees of execution correctness. We also performed path analysis to infer causal relationships between ongoing anticipatory brain activity, evoked semantic responses, expertise measures and behavioral performance. We found that anticipatory justify activity, with sources in a fronto-parieto-occipital network, early discriminated between groups according to their level of expertise. Furthermore, this early activity significantly predicted subsequent semantic integration indexed by semantic responses (N400 and SW, sourced in temporal and motor regions) which also predicted motor expertise. In addition, motor expertise was a good predictor of behavioral performance. Our results show that neural and temporal dynamics underlying contextual action anticipation and comprehension can be interpreted in terms of successive levels of contextual prediction that are significantly modulated by subject‟s prior experience.

Los pacientes con lesiones de la ínsula (al igual que las de áreas frontales) presentan un desempeño muy variable respecto el reconocimiento de las emociones, la empatía y la cognición social, que va desde la total afección a la total preservación. Dicha variabilidad podría explicarse por neuroplasticidad, procesos compensatorios y remapeo funcional. En este trabajo proponemos que la conectividad efectiva y el modelo de predictive coding representan una nueva aproximación para comprender dicha variabilidad a partir de las conexiones direccionales con otras áreas.

La neuroeducación busca detectar problemas en las prácticas escolares y proponer soluciones guiadas por evidencia neurocognitiva. En este sentido, la acumulación de conocimientos sobre el cerebro bilingüe permite reflexionar sobre las propuestas de enseñanza de lenguas extranjeras. El presente artículo aborda dicha temática mediante una lectura crítica de los Diseños Curriculares (DCs) para la Educación Básica de la Provincia de Buenos Aires. Específicamente, se consideran hallazgos neurolingüísticos para analizar los DCs en lo concerniente a la enseñanza de la gramática inglesa y sugerir modificaciones generales para superar las inconsistencias advertidas.

In the present work we analyzed the effect of contextual word predictability on the eye movement behavior of patients with mild Alzheimer disease (AD) compared to age-matched controls, by using the eyetracking technique and lineal mixed models. Twenty AD patients and 40 age-matched controls participated in the study. We first evaluated gaze duration during reading low and highly predictable sentences. AD patients showed an increase in gaze duration, compared to controls, both in sentences of low or high predictability. In controls, highly predictable sentences led to shorter gaze durations; by contrary, AD patients showed similar gaze durations in both types of sentences. Similarly, gaze duration in controls was affected by the cloze predictability of word N and N+1, whereas it was the same in AD patients. In contrast, the effects of word frequency and word length were similar in controls and AD patients. Our results imply that contextual-word predictability, whose processing is proposed to require memory retrieval, facilitated reading behavior in healthy subjects, but this facilitation was lost in early AD patients. This loss might reveal impairments in brain areas such as those corresponding to working memory, memory retrieval, and semantic memory functions that are already present at early stages of AD. In contrast, word frequency and length processing might require less complex mechanisms, which were still retained by AD patients. To the best of our knowledge, this is the first study measuring how patients with early AD process well-defined words embedded in sentences of high and low predictability. Evaluation of the resulting changes in eye movement behavior might provide a useful tool for a more precise early diagnosis of AD.

An enduring question is unity vs. separability of executive deficits resulting from impaired frontal lobe function. In previous studies, we have asked how executive deficits link to a conventional measure of fluid intelligence, obtained either by standard tests of novel problem-solving, or by averaging performance in a battery of novel tasks. For some classical executive tasks, such as the Wisconsin Card Sorting Test (WCST), Verbal Fluency, and Trail Making Test B (TMTB), frontal deficits are entirely explained by fluid intelligence. However, on a second set of executive tasks, including tests of multitasking and decision making, deficits exceed those predicted by fluid intelligence loss. In this paper we discuss how these results shed light on the diverse clinical phenomenology observed in frontal dysfunction, and present new data on a group of 15 schizophrenic patients and 14 controls. Subjects were assessed with a range of executive tests and with a general cognitive battery used to derive a measure of fluid intelligence. Group performance was compared and fluid intelligence was introduced as a covariate. In line with our previous results, significant patient-control differences in classical executive tests were removed when fluid intelligence was introduced as a covariate. However, for tests of multitasking and decision making, deficits remained. We relate our findings to those of previous factor analytic studies describing a single principal component, which accounts for much of the variance of schizophrenic patients’ cognitive performance. We propose that this general factor reflects low fluid intelligence capacity, which accounts for much but not all cognitive impairment in this patient group. Partialling out the general effects of fluid intelligence, we propose, may clarify the role of additional, more specific cognitive impairments in conditions such as schizophrenia.