Cognitive and Neuropathophysiological Outcomes of Gamma-tACS in Dementia: A Systematic Review.

Despite the numerous pharmacological interventions targeting dementia, no disease-modifying therapy is available, and the prognosis remains unfavorable. A promising perspective involves tackling high-frequency gamma-band (> 30 Hz) oscillations involved in hippocampal-mediated memory processes, which are impaired from the early stages of typical Alzheimer's Disease (AD). Particularly, the positive effects of gamma-band entrainment on mouse models of AD have prompted researchers to translate such findings into humans using transcranial alternating current stimulation (tACS), a methodology that allows the entrainment of endogenous cortical oscillations in a frequency-specific manner. This systematic review examines the state-of-the-art on the use of gamma-tACS in Mild Cognitive Impairment (MCI) and dementia patients to shed light on its feasibility, therapeutic impact, and clinical effectiveness. A systematic search from two databases yielded 499 records resulting in 10 included studies and a total of 273 patients. The results were arranged in single-session and multi-session protocols. Most of the studies demonstrated cognitive improvement following gamma-tACS, and some studies showed promising effects of gamma-tACS on neuropathological markers, suggesting the feasibility of gamma-tACS in these patients anyhow far from the strong evidence available for mouse models. Nonetheless, the small number of studies and their wide variability in terms of aims, parameters, and measures, make it difficult to draw firm conclusions. We discuss results and methodological limitations of the studies, proposing possible solutions and future avenues to improve research on the effects of gamma-tACS on dementia.

Facing Pediatric Rheumatic Diseases: The Role of Disease Activity and Parental Emotion Regulation Strategy in Parents' and Children's Psychological Adjustment.

BACKGROUND: Pediatric rheumatic diseases (PRDs) are a group of chronic disorders that start in childhood and are characterized by periodic exacerbations and remissions of symptoms, with limitations in family, school, and social activities. The aim of this study was to detect differences in parents' psychological adjustment and emotion regulation strategies, and parent-reported children's adjustments in families of children with active and inactive PRDs. METHODS: Fifty-four parents (38 mothers and 16 fathers) of children with PRD were recruited from a pediatric unit. Disease activity was evaluated by their pediatric rheumatologist, while parents' depressive and anxiety symptoms, emotion regulation strategies, and children's emotional difficulties and hyperactivity-inattention symptoms were assessed through a web-based survey. RESULTS: Parents of children with active PRDs reported higher levels of their child's emotional difficulties and hyperactivity-inattention symptoms. Linear regression analysis demonstrated that having a child in the active phases of PRD and lower use of cognitive reappraisal lead to higher children's emotional symptoms, while active disease, low use of cognitive reappraisal, and greater expressive suppression were associated with higher hyperactivity-inattention symptoms. Our study highlights that children with PRDs and their parents may be at increased risk for psychological problems, especially during the active disease phase, highlighting the importance of a multidisciplinary approach.

The Neural Correlates of Developmental Prosopagnosia: Twenty-Five Years on.

Faces play a crucial role in social interactions. Developmental prosopagnosia (DP) refers to the lifelong difficulty in recognizing faces despite the absence of obvious signs of brain lesions. In recent decades, the neural substrate of this condition has been extensively investigated. While early neuroimaging studies did not reveal significant functional and structural abnormalities in the brains of individuals with developmental prosopagnosia (DPs), recent evidence identifies abnormalities at multiple levels within DPs' face-processing networks. The current work aims to provide an overview of the convergent and contrasting findings by examining twenty-five years of neuroimaging literature on the anatomo-functional correlates of DP. We included 55 original papers, including 63 studies that compared the brain structure (MRI) and activity (fMRI, EEG, MEG) of healthy control participants and DPs. Despite variations in methods, procedures, outcomes, sample selection, and study design, this scoping review suggests that morphological, functional, and electrophysiological features characterize DPs' brains, primarily within the ventral visual stream. Particularly, the functional and anatomical connectivity between the Fusiform Face Area and the other face-sensitive regions seems strongly impaired. The cognitive and clinical implications as well as the limitations of these findings are discussed in light of the available knowledge and challenges in the context of DP.

Hemispheric functional asymmetries and sex effects in visual bistable perception.

This study investigates bistable perception as a function of the presentation side of the ambiguous figures and of participants' sex, to evaluate left-right hemispheric (LH-RH) asymmetries related to consciousness. In two experiments using the divided visual field paradigm, two Rubin's vase-faces figures were projected simultaneously and continuously 180 s long to the left (LVF) and right (RVF; Experiment 1) or to the upper (UVF) and lower (DVF; Experiment 2) visual hemifields of 48 healthy subjects monitored with eye-tracker. Experiment 1 enables stimulus segregation from the LVF to the RH and from the RVF to the LH, whereas Experiment 2 does not. Results from Experiment 1 show that males perceived the face profiles for more time in the LVF than in the RVF, with an opposite trend for the vase, whereas females show a similar pattern of perception in the two hemifields. A related result confirmed the previously reported possibility to have simultaneously two different percepts (qualia) in the two hemifields elicited by the two identic ambiguous stimuli, which was here observed to occur more frequently in males. Similar effects were not observed in Experiment 2. These findings suggest that the percepts display the processing abilities of the hemisphere currently processing the stimulus eliciting them (e.g., RH-faces), and that females and males reflect in bistable perception, a genuine manifestation of consciousness, the well-known hemispheric asymmetry differences they show in ordinary perception.

Investigating the impact of disposable surgical face-masks on face identity and emotion recognition in adults with autism spectrum disorder.

With the outburst of the COVID-19 pandemic, disposable surgical face-masks (DSFMs) have been widely adopted as a preventive measure. DSFMs hide the bottom half of the face, thus making identity and emotion recognition very challenging, both in typical and atypical populations. Individuals with autism spectrum disorder (ASD) are often characterized by face processing deficits; thus, DSFMs could pose even a greater challenge for this population compared to typically development (TD) individuals. In this study, 48 ASDs of level 1 and 110 TDs underwent two tasks: (i) the Old-new face memory task, which assesses whether DSFMs affect face learning and recognition, and (ii) the Facial affect task, which explores DSFMs' effect on emotion recognition. Results from the former show that, when faces were learned without DSFMs, identity recognition of masked faces decreased for both ASDs and TDs. In contrast, when faces were first learned with DSFMs, TDs but not ASDs benefited from a "context congruence" effect, that is, faces wearing DSFMs were better recognized if learned wearing DSFMs. In addition, results from the Facial affect task show that DSFMs negatively impacted specific emotion recognition in both TDs and ASDs, although differentially between the two groups. DSFMs negatively affected disgust, happiness and sadness recognition in TDs; in contrast, ASDs performance decreased for every emotion except anger. Overall, our study demonstrates a general, although different, disruptive effect on identity and emotion recognition both in ASD and TD population.

The effects of transcranial random noise stimulation on motor function: A comprehensive review of the literature.

The present review considers all papers published on the topic up to the end of the year 2022. Transcranial random noise stimulation (tRNS) is a non-invasive neuromodulation technique introduced about 15 years ago whose use is becoming increasingly widespread in neuroscience. It consists of the application over the scalp of a weak, white noise-like current, through electrodes having a surface of several square centimetres, for a duration ranging from seconds to minutes. Despite its relatively low spatial and temporal resolution, tRNS has well defined effects on central motor excitability, which critically depend on stimulation parameters. These effects seem to be chiefly based on an effect on neuronal membrane sodium channels and can last much longer than the stimulation itself. While the effects at the cellular level in the motor cortex are becoming progressively clear, much more studies are needed to understand the effects of tRNS on motor behaviour and performance, where initial research results are nevertheless promising, in both basic and applied research.

Comparing parental distress and children's difficulties between parents of children with rheumatic diseases and parents of healthy children in families facing the COVID-19 pandemic.

The COVID-19 pandemic could be a threat for the health status of children with a chronic condition. The present study aimed to explore parents' and children's psychological adjustment during the current pandemic, pursuing a triple objective: to compare the psychological adjustment of parents of children with pediatric rheumatic diseases (PRDs) and parents of healthy children; to analyze children's psychological symptoms (emotional problems and hyperactivity) before and during the COVID-19 pandemic, and with or without a PRDs diagnosis; to explore the associations of children's emotional problems and hyperactivity with parents' psychological adjustment, parent-child interactions and belonging or not to families with PRDs. This cross-sectional study involved 56 parents of children with PRDs and 53 parents of healthy children. Self-report questionnaires about parents' depression, anxiety, parenting stress, and children's emotional symptoms and hyperactivity-inattention were administered. No differences were detected on psychological adjustment between parents of children with PRDs and parents of healthy children. Parents of children with PRDs reported statistically significant higher levels of children's emotional problems and hyperactivity before the pandemic, compared to parents of healthy children; during COVID-19 pandemic, emotional symptoms increased for both groups, while hyperactivity-inattention symptoms increased only in the group of healthy children. Children's emotional difficulties were associated with higher levels of parental anxiety, worse parent-child interaction and having PRDs; children's hyperactivity symptoms were related to parent-child difficult interaction and higher levels of parental depression. Findings suggest the importance to target the children in relation to their parents, when approaching the psychological aspects of PRDs.

Crying the blues: The configural processing of infant face emotions and its association with postural biases.

Several studies have exploited the face inversion paradigm to unveil the mechanisms underlying the processing of adult faces, showing that emotion recognition relies more on a global/configural processing for sadness and on a piecemeal/featural processing for happiness. This difference might be due to the higher biological salience of negative rather than positive emotions and consequently should be higher for infant rather than adult faces. In fact, evolution might have promoted specific adaptations aimed to prioritize the infant face by the attention system in order to foster survival during infancy, a rather long period during which the newborn depends entirely on adults. Surprisingly, no study has yet exploited this paradigm to investigate the processing of emotions from infant faces. In this study, the face inversion paradigm was used to explore emotion recognition of infant compared with adult faces in a sample of adult participants. In addition, the existence of potential differences associated with specific postural biases (e.g., the left-cradling bias) during interactions with infants was explored. The presence of rotational effects for the recognition of both happy and sad infant faces suggests that infant face emotions are predominantly processed in a configural fashion, this perceptual effect being more evident in sadness. Results are discussed in the context of the biological and social salience of the emotional infant face.

An update on the use of gamma (multi)sensory stimulation for Alzheimer's disease treatment.

Alzheimer's disease (AD) is characterized by reduced fast brain oscillations in the gamma band (γ, > 30 Hz). Several animal studies show that inducing gamma oscillations through (multi)sensory stimulation at 40 Hz has the potential to impact AD-related cognitive decline and neuropathological processes, including amyloid plaques deposition, neurofibrillary tangles formation, and neuronal and synaptic loss. Therefore Gamma Entrainment Using Sensory stimulation (GENUS) is among the most promising approaches for AD patients' treatment. This review summarizes the evidence on GENUS effectiveness, from animal models to AD patients. Despite the application on human is in its infancy, the available findings suggest its feasibility for the treatment of AD. We discuss such results in light of parameter improvement and possible underlying mechanisms. We finally emphasize the need for further research for its development as a disease-modifying non-pharmacological intervention.

How head and visual movements affect evaluations of food products.

Many studies suggest that specific movements or postures with shared social meaning can influence mainly verbal stimuli evaluation. On the other hand, several visuospatial biases can interact with this influence. Thus, we tested whether both head and stimuli movements can influence individual attitude towards food pictures. In two experiments, we used images of common foods with a weak positive valence in association with two kinds of movements. In Experiment 1, head movement was induced by presenting food pictures with a vertical or horizontal continuous movement on a computer screen. Conversely, Experiment 2 was conducted to test the effects of participants' own head movements with respect to the same food pictures presented in a fixed position. In neither case did head movements influence product evaluation. However, Experiment 1 revealed that the continuous movement left-right-left in the horizontal condition improved the desire to buy and eat, as well as the willingness to pay for the product shown. Two further experiments, the Experiments 3 and 4 demonstrated, respectively, that this effect disappears if the stimulus does not make the return direction, and that it does not depend on the starting or final placement of the images on the screen. These findings are discussed in the context of embodied cognition and visuospatial bias theories.

Italian breakfast in mind: The effect of caffeine, carbohydrate and protein on physiological state, mood and cognitive performance.

Due to the bidirectional influence between eating and mental activity, there is a growing interest in the neurosciences in the potential of food to influence mental states. Breakfast is the most investigated meal since it is supposed to influence satiety, mood and cognitive performance for the rest of the day. However, there is insufficient consistency among studies to draw firm conclusions about the short-term influence of carbohydrates and proteins on self-reported physiological state and mood. In order to shed light on this topic, 40 young Italian adults were involved in a single-blind randomized counterbalanced crossover experiment, in which we asked them to report on a series of visuo-analogue scales their physiological (i.e., hunger, tiredness and thirst) and affective states (i.e., happiness, excitement, activeness and relaxation) and perform 2 computer-administered cognitive tasks (simple reaction time and forward digit span) before and after having breakfast with a bitter espresso coffee and a whole wheat or a protein croissant. Our data show that breakfast improves the self-reported mood and physiological state, and also short-term verbal memory assessed by means of the forward digit span: we suppose that both croissants and caffeine played an important role in such findings. As for the reaction times, the whole wheat croissant intake determined slower reaction time compared with the protein croissant, maybe due to the higher glycemic response induced by carbohydrate ingestion. Confirming the bidirectional relationship between mind and food intake, the present findings are significant for nutrition science, since mood, physiological state and cognitive performance play a substantial role in general well-being as well as in eating behavior.

How emotional is a banknote? The affective basis of money perception.

Previous studies have shown that money possesses affective properties even when it is not at stake within a given task. Smaller economic values are generally perceived as less arousing and neutral in valence, whereas larger ones are perceived as more arousing and positive in valence. Moreover, numerical cognitive processes seem to be less prominent than affective ones in the way we perceive economic values. To shed light on the basic affective components of monetary values, we ran three experiments on the perception of banknotes to test (i) whether banknotes with different values (5€ and 100€) trigger different emotional states, (ii) if values are horizontally mapped based on their valence, rather than on their numerical magnitude, and (iii) whether the lateralized sight (in the left or right visual field) of a positive (higher) monetary value interferes with the classification of a negative stimulus. Results showed a coherent pattern that corroborates the idea that money is indeed an affective stimulus, even when it is not at stake within the task. A higher monetary value was shown (i) to have intrinsic rewarding properties that influence the evaluation of a subsequent target, (ii) to be mentally mapped on the right side, which is related to positive approaching of affective stimuli in right-handers, and (iii) to be in conflict with negative-withdrawing targets, but only when the values were presented on the right-positive side of respondents. Results are discussed considering existing theories of the psychological value of money, highlighting the hedonic characteristics of this special affective stimulus.

Affective perception of Euro banknotes: cognitive factors and interindividual differences.

Money can be a tool to achieve a wide range of goals in everyday life. Different studies have reported that both the mere exposure to money and its use as a reward can determine cognitive and social effects. Nevertheless, little is known about the basic affective perception of Euro banknotes. Thus, in the present study we aim to assess differences in valence, arousal and familiarity evaluations of banknote pictures (from 5 to 500€) by taking into account gender, socioeconomic status and Love of Money (LoM) score, which measures the subjective attitude toward money, in a sample of participants. We found that valence and arousal increase with the nominal value of the banknotes, and that the relationship between these affective scores and the nominal value appears to be logarithmic (Weber's law) rather than linear. High value banknotes were evaluated as pleasant, highly arousing, and less familiar. Low value banknotes instead were evaluated as more familiar, less arousing and neutrally valenced. Finally, we found that valence and arousal evaluations are mainly influenced by the LoM score of our participants. Instead, gender and economic condition influenced only arousal scores. These findings suggest the importance of deepening the study of these variables to shed light on money-related biases and abnormal economic behaviors.

A computationally efficient method for the attenuation of alternating current stimulation artifacts in electroencephalographic recordings.

OBJECTIVE: Recent studies suggest that the use of noninvasive closed-loop neuromodulation combining electroencephalography (EEG) and transcranial alternating current stimulation (tACS) may be a promising avenue for the treatment of neurological disorders. However, the attenuation of tACS artifacts in EEG data is particularly challenging, and computationally efficient methods are needed to enable closed-loop neuromodulation experiments. Here we introduce an original method to address this methodological issue. APPROACH: Our alternating current regression (AC-REG) method is an adaptive (time-varying) spatial filtering method. It relies on a data buffer of preset size, on which principal component analysis (PCA) is applied. The resulting components are used to build a spatial filter capable of regressing periodic signals in phase with the stimulation. PCA is performed each time that a new sample enters the buffer, such that the spatial filter can be continuously updated and applied to the EEG data. MAIN RESULTS: The AC-REG accuracy in terms of tACS artifact attenuation was assessed using simulated and real EEG data. Alternative offline processing techniques, such as the superimposition of moving averages (SMA) and the Helfrich method (HeM), were used as benchmark. Using simulations, we found that AC-REG can yield a more reliable reconstruction of the stimulation signal for any frequency between 1 and 80 Hz. Analysis of real EEG data of 18 healthy volunteers showed that AC-REG was able to better recover hidden neural activity as compared to SMA and HeM. Also, significantly higher correlations between power spectrum densities in tACS on and off conditions, respectively, were obtained using AC-REG (r = 0.90) than using SMA (r = 0.80) and HeM (r = 0.86). SIGNIFICANCE: Thanks to its low computational complexity, the AC-REG method can be employed in noninvasive closed-loop neuromodulation experiments, with potential applications both in healthy individuals and in neurological patients.

Healthiness or calories? Side biases in food perception and preference.

The visual perception of a product and the ability to categorize it play a central role in food choice. People's opinion of the healthiness and caloric content of a food is influenced substantially by its appearance. Despite that, few studies have analyzed i) which one of the two dimensions of caloric content and healthiness is preferred to categorize food, ii) if these dimensions are mapped on the individuals' horizontal space, and iii) if such biases could influence food preferences. Therefore, through 4 experiments, we investigated which dimension, healthiness or caloric content, is more often used to categorize foods. We also evaluated whether a healthiness/caloric content side bias could be able to influence food preferences. We found that foods were mainly categorized as "Healthy" or "High-calorie" and the latter label was used more often when presented on the right of a foodstuff. Also, foods were categorized as healthier when the "Healthy" label was anchored to the left and the "Unhealthy" one to the right side of a visual analogue scale. Then, we found a more positive evaluation of transformed food when the key assigned to the "Pleasant" choice was on the right compared to the left. Lastly, we found that when presented on the left side, low-calorie was preferred compared to high-calorie food. Our findings shed light on both the fields of food categorization and side biases in food perception and preferences, suggesting the possibility to use these biases to promote a healthy diet and emphasizing the importance of considering this potential confounder in experimental setups.

Side Biases in Euro Banknotes Recognition: The Horizontal Mapping of Monetary Value.

Money is a special stimulus for humans, because of its relevance in everyday life. However, the basic mechanisms underlying money representation have not yet been fully investigated. Left-right asymmetries in the visual perception and evaluation of monetary value offer such a possibility. The pattern of these asymmetries can contribute to disentangle between numerical and emotional processes possibly involved in banknotes perception. In the present experiment, we tested the recognition of 5€and 100€ banknotes presented in the left and right visual fields. Results show that the 100€ banknote is recognized faster than the 5€ banknote in the Right Visual Field (RVF), while there is no difference in the Left Visual Field (LVF). Our interpretation is that this effect is due to the matching between the positive valence conveyed by the 100€ banknote and the side in which it is mapped (right-positive). We consider this result as evidence of a valence-based recognition of banknotes.

Emotional faces influence evaluation of natural and transformed food.

Previous evidence showed the presence of a straight relationship between feeding behavior and emotions. Despite that, no studies have focused on the influence of emotional faces on food processing. In our study, participants were presented with 72 couples of visual stimuli composed of a neutral, happy, or disgusted faces (5000 ms duration in Experiment 1, adaptation; 150 ms in Experiment 2, priming) followed by a food stimulus (1500 ms). Food stimuli were grouped in pleasant foods, further divided in natural and transformed, and unpleasant rotten foods. The task consisted in judging the food valence (as 'pleasant' or 'unpleasant') by keypress. Results showed a different pattern of response based on the transformation level of food. In general, the evaluation of natural foods was more rapid compared with transformed foods, maybe for their simplicity and healthier perception. In addition, transformed foods yielded incongruent responses with respect to the preceding emotional face, whereas natural foods yielded congruent responses with respect to it. These effects were independent of the duration of the emotional face (i.e., adaptation or priming paradigm) and may depend on pleasant food stimuli salience.

Author Correction: Emotional faces influence evaluation of natural and transformed food.

This article unfortunately contained two mistakes.