The interaction between motor simulation and spatial perspective-taking in action language: a cross-cultural study.

Growing evidence has revealed the crucial role of motor simulation and spatial perspective-taking in action language. However, there is still a lack of understanding of how motor and spatial processes interact when there are multiple actors involved, and if embodied processes are consistent across different cultures. To address this gap, we examined the interaction between motor simulation and spatial perspective-taking in action-sentences comprehension, along with the consistency of embodied processes across cultures. We collected data from Italian and US English speakers using an online sentence-picture verification task. The participants completed four conditions: two congruent (i.e., the participant is the agent in the sentence and the photo; the agent is someone else interacting with the participant in both the sentence and the picture) and two incongruent (i.e., the agents of the sentence and the picture do not match). The results show that when the perspective of the picture matched that described in the sentence-processing reaction times (RTs) were faster than in the incongruent conditions. In the congruent conditions where the agent is someone else, RTs were slower compared to the condition where the participant is the agent. This has been interpreted as claiming that motor simulation and perspective-taking are independent processes interacting during sentence comprehension (e.g., motor simulation is always run in the role of the agent, but we can adopt multiple perspectives depending on the pronouns and the contextual cues). Furthermore, Bayesian analysis provided evidence that embodied processing of action language entwines a common mechanism, suggesting cross-cultural consistency of embodied processes.

The Italian Sensorimotor Norms: Perception and action strength measures for 959 words.

Neuroscience research has provided evidence that semantic information is stored in a distributed brain network involved in sensorimotor and linguistic processing. More specifically, according to the embodied cognition accounts, the representation of concepts is deemed as grounded in our bodily states. For these reasons, normative measures of words should provide relevant information about the extent to which each word embeds perceptual and action properties. In the present study, we collected ratings for 959 Italian nouns and verbs from 398 volunteers, recruited via an online platform. The words were mostly taken from the Italian adaptation of the Affective Norms for English Words (ANEW). A pool of 145 verbs was added to the original set. All the words were rated on 11 sensorimotor dimensions: six perceptual modalities (vision, audition, taste, smell, touch, and interoception) and five effectors (hand-arm, foot-leg, torso, mouth, head). The new verbs were also rated on the ANEW dimensions. Results showed good reliability and consistency with previous studies. Relations between perceptual and motor dimensions are described and interpreted, along with relations between the sensorimotor and the affective dimensions. The currently developed dataset represents an important novelty, as it includes different word classes, i.e., both nouns and verbs, and integrates ratings of both sensorimotor and affective dimensions, along with other psycholinguistic parameters; all features only partially accomplished in previous studies.

A double-blind randomized controlled trial combining cognitive training (CoRe) and neurostimulation (tDCS) in the early stages of cognitive impairment.

BACKGROUND: The prevalence of neurodegenerative diseases is expected to increase over the next years, therefore, new methods able to prevent and delay cognitive decline are needed. AIMS: To evaluate the effectiveness of a combined treatment protocol associating a computerized cognitive training (CoRe) with anodal transcranial direct current stimulation (tDCS). METHODS: In this randomized controlled trial, 33 patients in the early stage of cognitive impairment were assigned to the experimental group (CoRE + real tDCS) or control group (CoRE + sham tDCS). In each group, the intervention lasted 3 consecutive weeks (4 sessions/week). A neuropsychological assessment was administered at baseline (T0), post-intervention (T1) and 6-months later (T2). RESULTS: The CoRE + real tDCS group only improved in working memory and attention/processing speed at both T1 and T2. It reported a stable MMSE score at T2, while the CoRE + sham tDCS group worsened. Age, mood, and T0 MMSE score resulted to play a role in predicting treatment effects. CONCLUSION: Combined multi-domain interventions may contribute to preventing or delaying disease progression. TRIAL REGISTRATION: Trial registration number (ClinicalTrials.gov): NCT04118686.

tDCS effects on brain network properties during physiological aging.

Brain neural networks undergo relevant changes during physiological aging, which affect cognitive and behavioral functions. Currently, non-invasive brain stimulation techniques, such as transcranial direct current stimulation (tDCS), are proposed as tools able to modulate cognitive functions in brain aging, acting on networks properties and connectivity. Segregation and integration measures are used and evaluated by means of local clustering (segregation) and path length (integration). Moreover, to assess the balancing between them, the Small World (SW) parameter is employed, evaluating functional coupling in normal brain aging and in pathological conditions including neurodegeneration. The aim of this study was to systematically investigate the tDCS-induced effects on brain network proprieties in physiological aging. In order to reach this aim, cortical activity was acquired from healthy young and elderly subjects by means of EEG recorded before, during, and after anodal, cathodal, and sham tDCS sessions. Specifically, the aim to exploring tDCS polarity-dependent changes in the age-dependent network dynamics was based on a network graph theory application on two groups divided in young and elderly subjects. Eighteen healthy young (9 females; mean age = 24.7, SD = 3.2) and fifteen elderly subjects (9 females; mean = 70.1, SD = 5.1) were enrolled. Each participant received anodal, cathodal, or sham tDCS over the left prefrontal cortex (PFC) in three separate experimental sessions performed 1 week apart. SW was computed to evaluate brain network organization. The present study demonstrates that tDCS delivered in PFC can change brain network dynamics, and tDCS-EEG coregistration data can be analyzed using graph theory to understand the induced effects of different tDCS polarities in physiological and pathological brain aging.

Anodal Transcranial Direct Current Stimulation Promotes Frontal Compensatory Mechanisms in Healthy Elderly Subjects.

Recent studies have demonstrated that transcranial direct current stimulation (tDCS) is potentially useful to improve working memory. In the present study, young and elderly subjects performed a working memory task (n-back task) during an electroencephalogram recording before and after receiving anodal, cathodal, and sham tDCS over the left dorsolateral prefrontal cortex (DLPFC). We investigated modulations of behavioral performance and electrophysiological correlates of working memory processes (frontal and parietal P300 event-related potentials). A strong tendency to modulated working memory performance was observed after the application of tDCS. In detail, young, but not elderly, subjects benefited from additional practice in the absence of real tDCS, as indicated by their more accurate responses after sham tDCS. The cathodal tDCS had no effect in any group of participants. Importantly, anodal tDCS improved accuracy in elderly. Moreover, increased accuracy after anodal tDCS was correlated with a larger frontal P300 amplitude. These findings suggest that, in elderly subjects, improved working memory after anodal tDCS applied over the left DLPFC may be related to the promotion of frontal compensatory mechanisms, which are related to attentional processes.

The interaction with task-induced activity is more important than polarization: a tDCS study.

BACKGROUND: Anodal transcranial direct current stimulation (A-tDCS) is a non-invasive technique in which cortical polarization can be used to increase excitability and facilitate learning through the modulation of neuroplasticity. Although the facilitatory effects of A-tDCS are well documented, there is evidence that they are not always present and may even be reversed during task execution. OBJECTIVE: In this study, we explored the interaction between A-tDCS and task execution. We aimed to test how the excitability induced by the task interacts with the excitability induced by A-tDCS and determines the behavioral outcome. METHODS: We performed an experiment in which A-tDCS or a control stimulation (Ctrl) were combined with one of two motor practices (MP), one inducing learning and increasing cortical excitability (F-MP) and the other neither inducing learning nor changing cortical excitability (S-MP). Six blocks of MP were performed while the primary motor cortex was stimulated. Moreover, one block of F-MP was performed before the stimulation (baseline) and one after. In an additional experiment, motor evoked potentials (MEPs) were recorded before the baseline block (TMS-pre) and after the MP (TMS-post). RESULTS: We observed that A-tDCS reduced learning when participants performed the F-MP and facilitated learning for the S-MP. MEPs data paralleled behavioral results, confirming that the effects generated by A-tDCS depend on the excitability changes induced by the task. CONCLUSIONS: Our results demonstrate that tDCS-induced plasticity is task-dependent, and the concurrent combination of A-tDCS with another excitability-increasing event, e.g., motor practice, may trigger non-additive mechanisms, hindering neuroplasticity.