Aperiodic and periodic components of oscillatory brain activity in relation to cognition and symptoms in pediatric ADHD.

Children with attention-deficit/hyperactivity disorder show deficits in processing speed, as well as aberrant neural oscillations, including both periodic (oscillatory) and aperiodic (1/f-like) activity, reflecting the pattern of power across frequencies. Both components were suggested as underlying neural mechanisms of cognitive dysfunctions in attention-deficit/hyperactivity disorder. Here, we examined differences in processing speed and resting-state-Electroencephalogram neural oscillations and their associations between 6- and 12-year-old children with (n = 33) and without (n = 33) attention-deficit/hyperactivity disorder. Spectral analyses of the resting-state EEG signal using fast Fourier transform revealed increased power in fronto-central theta and beta oscillations for the attention-deficit/hyperactivity disorder group, but no differences in the theta/beta ratio. Using the parameterization method, we found a higher aperiodic exponent, which has been suggested to reflect lower neuronal excitation-inhibition, in the attention-deficit/hyperactivity disorder group. While fast Fourier transform-based theta power correlated with clinical symptoms for the attention-deficit/hyperactivity disorder group only, the aperiodic exponent was negatively correlated with processing speed across the entire sample. Finally, the aperiodic exponent was correlated with fast Fourier transform-based beta power. These results highlight the different and complementary contribution of periodic and aperiodic components of the neural spectrum as metrics for evaluation of processing speed in attention-deficit/hyperactivity disorder. Future studies should further clarify the roles of periodic and aperiodic components in additional cognitive functions and in relation to clinical status.

The importance of individual beliefs in assessing treatment efficacy.

In recent years, there has been debate about the effectiveness of treatments from different fields, such as neurostimulation, neurofeedback, brain training, and pharmacotherapy. This debate has been fuelled by contradictory and nuanced experimental findings. Notably, the effectiveness of a given treatment is commonly evaluated by comparing the effect of the active treatment versus the placebo on human health and/or behaviour. However, this approach neglects the individual's subjective experience of the type of treatment she or he received in establishing treatment efficacy. Here, we show that individual differences in subjective treatment - the thought of receiving the active or placebo condition during an experiment - can explain variability in outcomes better than the actual treatment. We analysed four independent datasets (N = 387 participants), including clinical patients and healthy adults from different age groups who were exposed to different neurostimulation treatments (transcranial magnetic stimulation: Studies 1 and 2; transcranial direct current stimulation: Studies 3 and 4). Our findings show that the inclusion of subjective treatment can provide a better model fit either alone or in interaction with objective treatment (defined as the condition to which participants are assigned in the experiment). These results demonstrate the significant contribution of subjective experience in explaining the variability of clinical, cognitive, and behavioural outcomes. We advocate for existing and future studies in clinical and non-clinical research to start accounting for participants' subjective beliefs and their interplay with objective treatment when assessing the efficacy of treatments. This approach will be crucial in providing a more accurate estimation of the treatment effect and its source, allowing the development of effective and reproducible interventions.

Neuromodulation is a type of intervention that relies on various non-invasive techniques to temporarily stimulate the brain and nervous system. It can be used for the treatment of depression or other medical conditions, as well as the improvement of cognitive abilities such as attention. However, there is conflicting evidence regarding whether this approach has beneficial effects. Most studies aiming to assess the efficiency of a treatment rely on examining the outcomes of people who received the intervention in comparison to participants who undergo a similar procedure with no therapeutic effect (or placebo). However, the influence of other, 'subjective' factors on these results ­ such as the type of intervention participants think they have received ­ remains poorly investigated. To bridge this gap, Fassi and Hochman et al. used statistical modeling to assess how patients' beliefs about their treatment affected the results of four neuromodulation studies on mind wandering, depression and attention deficit hyperactivity disorder symptoms. In two studies, participants' perceptions of their treatment status were more strongly linked to changes in depression scores and mind-wandering than the actual treatment. Results were more nuanced in the other two studies. In one of them, participants who received the real neuromodulation but believed they received the placebo showed the most improvement in depressive symptoms; in the other study, subjective beliefs and objective treatment both explained changes in inattention symptoms. Taken together, the results by Fassi and Hochman et al. suggest that factoring in patients' subjective beliefs about their treatment may be necessary in studies of neuromodulation and other interventions like virtual reality or neurofeedback, where participants are immersed in cutting-edge research settings and might therefore be more susceptible to develop beliefs about treatment efficacy.

Reliable affordances: A generative modeling approach for test-retest reliability of the affordances task.

The affordances task serves as an important tool for the assessment of cognition and visuomotor functioning, and yet its test-retest reliability has not been established. In the affordances task, participants attend to a goal-directed task (e.g., classifying manipulable objects such as cups and pots) while suppressing their stimulus-driven, irrelevant reactions afforded by these objects (e.g., grasping their handles). This results in cognitive conflicts manifesting at the task level and the response level. In the current study, we assessed the reliability of the affordances task for the first time. While doing so, we referred to the "reliability paradox," according to which behavioral tasks that produce highly replicable group-level effects often yield low test-retest reliability due to the inadequacy of traditional correlation methods in capturing individual differences between participants. Alongside the simple test-retest correlations, we employed a Bayesian generative model that was recently demonstrated to result in a more precise estimation of test-retest reliability. Two hundred and ninety-five participants completed an online version of the affordances task twice, with a one-week gap. Performance on the online version replicated results obtained under in-lab administrations of the task. While the simple correlation method resulted in weak test-retest measures of the different effects, the generative model yielded a good reliability assessment. The current results support the utility of the affordances task as a reliable behavioral tool for the assessment of group-level and individual differences in cognitive and visuomotor functioning. The results further support the employment of generative modeling in the study of individual differences.

Transcranial random noise stimulation combined with cognitive training for treating ADHD: a randomized, sham-controlled clinical trial.

Non-invasive brain stimulation has been suggested as a potential treatment for improving symptomology and cognitive deficits in Attention-Deficit/Hyperactivity Disorder (ADHD), the most common childhood neurodevelopmental disorder. Here, we examined whether a novel form of stimulation, high-frequency transcranial random noise stimulation (tRNS), applied with cognitive training (CT), may impact symptoms and neural oscillations in children with ADHD. We conducted a randomized, double-blind, sham-controlled trial in 23 unmedicated children with ADHD, who received either tRNS over the right inferior frontal gyrus (rIFG) and left dorsolateral prefrontal cortex (lDLPFC) or sham stimulation for 2 weeks, combined with CT. tRNS + CT yielded significant clinical improvements (reduced parent-reported ADHD rating-scale scores) following treatment, compared to the control intervention. These improvements did not change significantly at a 3-week follow-up. Moreover, resting state (RS)-EEG periodic beta bandwidth of the extracted peaks was reduced in the experimental compared to control group immediately following treatment, with further reduction at follow-up. A lower aperiodic exponent, which reflects a higher cortical excitation/inhibition (E/I) balance and has been related to cognitive improvement, was seen in the experimental compared to control group. This replicates previous tRNS findings in adults without ADHD but was significant only when using a directional hypothesis. The experimental group further exhibited longer sleep onset latencies and more wake-up times following treatment compared to the control group. No significant group differences were seen in executive functions, nor in reported adverse events. We conclude that tRNS + CT has a lasting clinical effect on ADHD symptoms and on beta activity. These results provide a preliminary direction towards a novel intervention in pediatric ADHD.

Human neuronal excitation/inhibition balance explains and predicts neurostimulation induced learning benefits.

Previous research has highlighted the role of the excitation/inhibition (E/I) ratio for typical and atypical development, mental health, cognition, and learning. Other research has highlighted the benefits of high-frequency transcranial random noise stimulation (tRNS)-an excitatory form of neurostimulation-on learning. We examined the E/I as a potential mechanism and studied whether tRNS effect on learning depends on E/I as measured by the aperiodic exponent as its putative marker. In addition to manipulating E/I using tRNS, we also manipulated the level of learning (learning/overlearning) that has been shown to influence E/I. Participants (n = 102) received either sham stimulation or 20-minute tRNS over the dorsolateral prefrontal cortex (DLPFC) during a mathematical learning task. We showed that tRNS increased E/I, as reflected by the aperiodic exponent, and that lower E/I predicted greater benefit from tRNS specifically for the learning task. In contrast to previous magnetic resonance spectroscopy (MRS)-based E/I studies, we found no effect of the level of learning on E/I. A further analysis using a different data set suggest that both measures of E/I (EEG versus MRS) may reflect, at least partly, different biological mechanisms. Our results highlight the role of E/I as a marker for neurostimulation efficacy and learning. This mechanistic understanding provides better opportunities for augmented learning and personalized interventions.

Asymmetric affective perspective taking effects toward valence influenced by personality perspective taken.

Previously, we found that taking perspectives of two polar targets of the neuroticism dimension of personality influenced affect evaluations of negative pictures more than positive pictures. As neuroticism is more reactive to negative affects, the current follow-up experiment explores the effect of affective perspective taking (APT) when perspectives are derived from extroversion, which is more reactive to positive affects. Stimuli consisted of neutral, sad, and happy pictures, which were rated from the perspectives of an introvert and an extrovert. Emotional strength rating was a dependent variable, and N = 41. We found a significant interaction between APT and valence. The difference in ratings between adopting an introverted and an extroverted perspective toward happiness was larger than toward sadness. Together with the results from our previous study, these results suggest an asymmetric influence of APT toward positive and negative valances and that the direction of influence asymmetry depends on the type of personality dimension from which perspectives are derived.

Perspective taking effects are modulated by the valence of stimuli.

Previously we found perspective taking (PT) influenced affect ratings of negative pictures more than neutral pictures. The current follow-up experiments extend that research to explore effects of perspective taking with positive valence pictures. We used stimuli consisting of neutral, happy and sad pictures. Stimuli were presented either mixed within blocks (Experiment 1) or separated by emotion (neutrals + happy/sad) into two separate blocks (Experiment 2). Participants rated (from 1- to 7 based on emotional strength) stimuli from different perspectives (sensitive/tough/their own, i.e., "me"). Emotional strength rating was a dependent variable. A significant interaction between valence and PT was found in both experiments. The difference between adopting sensitive and tough perspectives toward sadness was larger than toward the neutral condition, replicating our results from the previous study. The same difference (sensitive-tough) was larger toward the happiness condition than toward the neutral one (this was a trend in Experiment 1 and was significant in Experiment 2) and toward the sadness condition than toward the happy one. These results suggest that PT effects on emotional ratings are modulated by valence of stimuli.

Do you feel like me or not? This is the question: manipulation of emotional imagery modulates affective priming.

Mood congruity and affective priming have been used to study the effects of affective phenomena on perception. Manipulation of mood is appropriate for investigations of long-term effects while affective priming is limited to short intervals (approximately 300 ms) between a prime and target. However, studying the influence of real-world rapidly changing emotional episodes on perception may fall between the cracks of these methods. This may be caused, inter alia, because emotional episodes are distinguished from mood experiences on one hand, but often last for longer than roughly 300 ms on the other. Thus, it is unclear what experimental approach should be taken to investigate congruency effects triggered by emotional episodes. The present study used a new variation of the evaluation decision task (EDT) combined with a script-driven imagery procedure to investigate a possible congruency relationship between the evaluator's emotional experience at a given time and observable emotional markers of others. We used 180 9-word script-driven imageries as varying valence primes (negative, positive, neutral) and asked participants to imagine themselves in the situation described in the scripts. At the last stage of a trial, all participants were asked to evaluate the mood-positive or negative-of a target face of a child in a photograph. We manipulated the reading interval (4000 ms and 1350 ms) and the subsequent blank interval (300 ms, 5000 ms, and unlimited) until target onset. Prime and target valence were congruent or incongruent. Significant congruency effects were found for both short and long reading intervals and blank intervals. However, in longer blank intervals only the interference effect reached significance. Furthermore, the interference effect was found to be significant mainly in trials beginning with a negative script.

Tactile Enumeration and Embodied Numerosity Among the Deaf.

Representations of the fingers are embodied in our cognition and influence performance in enumeration tasks. Among deaf signers, the fingers also serve as a tool for communication in sign language. Previous studies in normal hearing (NH) participants showed effects of embodiment (i.e., embodied numerosity) on tactile enumeration using the fingers of one hand. In this research, we examined the influence of extensive visuo-manual use on tactile enumeration among the deaf. We carried out four enumeration task experiments, using 1-5 stimuli, on a profoundly deaf group (n = 16) and a matching NH group (n = 15): (a) tactile enumeration using one hand, (b) tactile enumeration using two hands, (c) visual enumeration of finger signs, and (d) visual enumeration of dots. In the tactile tasks, we found salient embodied effects in the deaf group compared to the NH group. In the visual enumeration of finger signs task, we controlled the meanings of the stimuli presentation type (e.g., finger-counting habit, fingerspelled letters, both or neither). Interestingly, when comparing fingerspelled letters to neutrals (i.e., not letters or numerical finger-counting signs), an inhibition pattern was observed among the deaf. The findings uncover the influence of rich visuo-manual experiences and language on embodied representations. In addition, we propose that these influences can partially account for the lag in mathematical competencies in the deaf compared to NH peers. Lastly, we further discuss how our findings support a contemporary model for mental numerical representations and finger-counting habits.

Conditioning automatic inhibition task: Introducing a novel task to associate automatic inhibition with specific cues.

There is growing interest in methods for conditioning automatic inhibition with specific stimuli and the potential clinical implications of these methods. For example, OCD patients were shown to benefit from a computerized training program which aimed to create an association between OCD-related cues and stopping behaviors. In the current study, we aimed to investigate the ability to condition inhibition to specific stimuli and whether such conditioning can be generalized between tasks to last over time. Participants completed 6 training sessions using a novel version of the stop-signal task, the 'conditioning automatic inhibition task' (CAIT), over a 48 -h period, in which one randomly chosen color patch was associated with inhibition. The classic Stroop task was administered before and after the CAIT training. Results yielded smaller congruency and interference effects in the Stroop task after training, but only for the color that was associated with stopping. These results demonstrate the effect of the CAIT onto one specific stimulus, and that the effect generalized between the training and testing tasks. This provides novel evidence that the CAIT can be used to facilitate faster recruitment of inhibitory resources for a specific trained stimulus, which might later help resolve cognitive conflicts that require inhibition and might also have important clinical implications.

Stopping at a red light: Recruitment of inhibitory control by environmental cues.

Environmental cues can influence basic perceptual and attentional processes especially in an emotional context. In the current study, we aimed to investigate the effect of a non-emotional common environmental cue-a traffic light-on a higher cognitive operation-inhibition. In two experiments, we administered a novel version of the stop-signal task, in which the go task was to determine the color of a traffic light. In order to investigate the influence of each of the cues on inhibitory processes, separate tracking procedures (one for each cue) were applied simultaneously to the stop-signal delay. In Experiment 1, we found that reaction time in no-stop-signal trials was faster when a green traffic light was present, whereas stop-signal reaction time was longer when a red traffic light was present. In Experiment 2, neutral control cues were used in addition to a red and green light. The results indicate that the differences between red and green stem from an association between the color red and stop processes (rather than from the green-go association). These results strengthen previous findings showing the effect of environmental cues on attentional processes and go beyond them by showing that the effect is not restricted to emotional cues. Most importantly, the current study results suggest that environmental cues can also influence complex cognitive operations such as inhibitory control. These results might have specific implications for our understanding of the processes that underlie specific psychiatric disorders characterized by inhibitory deficit.