Investigating mental representations of psychoactive substance use and other potentially addictive behaviors using a data driven network-based clustering method.

BACKGROUND AND AIMS: The aim of the present study was to examine the mental representations of the use of different substances and other potentially addictive behaviors in order to explore meaningful similarities and differences that may contribute to a better understanding of behavioral addictions' representations and diagnostic criteria. METHODS: The authors mapped the mental and emotional representations of 661 participants (70.5% women; Mage = 35.2 years, SD = 11.7) to the concept "your most disturbing excessive activity" using free-word associations combined with a network-based clustering method. RESULTS: The network analyses identified four distinct mental representations, three implicating dominantly negative (Guilt/Shame/Relief, Addiction/Health, and Procrastination/Boredom) and one dominantly positive emotion (Stress/Relaxation). The distribution of Addiction/Health and Procrastination/Boredom representations were different across substance use and problem behaviors, indicating meaningful differences in the underlying cognitive evaluation processes. The Addiction/Health representation was more frequent for substances, while for other addictive behaviors, the Procrastination/Boredom representation was more frequent, and its frequency increased with the self-reported intensity of the behavior. Guilt/Shame/Relief was equally common for both substances and behaviors, but importantly, for substances its' likelihood increased with the intensity of use. CONCLUSION: The common part of representations for substance use and other potentially addictive behaviors supports the scientific viewpoint, that real addictions can exist even in the absence of psychoactive drugs. Based on the results, a novel proposition is posited, that a more appropriate indicator of tolerance for problem behaviors might be the perceived amount of time wasted on the activity rather than the actual time spent.

Novel Insights into the Physiology of Nutrient Sensing and Gut-Brain Communication in Surgical and Experimental Obesity Therapy.

Despite standardized surgical technique and peri-operative care, metabolic outcomes of bariatric surgery are not uniform. Adaptive changes in brain function may play a crucial role in achieving optimal postbariatric weight loss. This review follows the anatomic-physiologic structure of the postbariatric nutrient-gut-brain communication chain through its key stations and provides a concise summary of recent findings in bariatric physiology, with a special focus on the composition of the intestinal milieu, intestinal nutrient sensing, vagal nerve-mediated gastrointestinal satiation signals, circulating hormones and nutrients, as well as descending neural signals from the forebrain. The results of interventional studies using brain or vagal nerve stimulation to induce weight loss are also summarized. Ultimately, suggestions are made for future diagnostic and therapeutic research for the treatment of obesity.

Attitudes of primary care physicians toward bariatric surgery: a free word association networks analysis.

BACKGROUND: Primary care physicians (PCPs) hold major responsibility in referring patients with obesity eligible for bariatric surgery (BS). OBJECTIVE: The aim was to explore PCPs' mental representation of BS in order to identify barriers and catalysts of BS referral practices. SETTING: Switzerland. METHODS: A total of 3526 PCPs were invited to participate in an online survey. PCPs were asked to write the first 5 words that came to their mind about the term "bariatric surgery." Additionally, they had to pick 2 emotions that best described each provided association. Demographic data and obesity-related referral patterns were collected. Mental representation network was constructed based on co-occurrence of associations, using validated data-driven methodology. RESULTS: In all, 216 PCPs completed the study (response rate: 6.13%). Respondents were aged 55 ± 9.8 years, had an equal sex distribution, and practiced mainly in urban settings. Three mental representations of BS emerged: indication-focused (most frequent associations: "obesity," "diabetes"), treatment-focused ("gastric bypass," "weight loss"), and outcome-focused ("complications," "challenging follow-up"). The emotional label "interested" was used significantly more frequently in the treatment-focused group. Comparison of PCPs among mental modules showed that those with a treatment-focused mindset referred patients for BS most frequently and were significantly more willing to follow up with postbariatric patients (χ2 = 17.8, P = .022). CONCLUSIONS: PCPs think about BS along 3 mental representations, and the treatment-focused attitude was coupled with the highest willingness to refer eligible patients for BS. Confidence in performing postbariatric follow-up was identified as catalyst of BS referral. Access to optimal care for patients with obesity may be improved accordingly.

Adolescent ADHD and electrophysiological reward responsiveness: A machine learning approach to evaluate classification accuracy and prognosis.

We evaluated event-related potential (ERP) indices of reinforcement sensitivity as ADHD biomarkers by examining, in N=306 adolescents (Mage=15.78, SD=1.08), the extent to which ERP amplitude and latency variables measuring reward anticipation and response (1) differentiate, in age- and sex-matched subsamples, (i) youth with vs. without ADHD, (ii) youth at-risk for vs. not at-risk for ADHD, and, in the with ADHD subsample, (iii) youth with the inattentive vs. the hyperactive/impulsive (H/I) and combined presentations. We further examined the extent to which ERP variables (2) predict, in the ADHD subsample, substance use (i) concurrently and (ii) prospectively at 18-month follow-up. Linear support vector machine analyses indicated ERPs weakly differentiate youth with/without (65%) - and at-risk for/not at-risk for (63%) - ADHD but better differentiate ADHD presentations (78%). Regression analyses showed in adolescents with ADHD, ERPs explain a considerable proportion of variance (50%) in concurrent alcohol use and, controlling for concurrent marijuana and tobacco use, explain a considerable proportion of variance (87 and 87%) in, and predict later marijuana and tobacco use. Findings are consistent with the dual-pathway model of ADHD. Results also highlight limitations of a dichotomous, syndromic classification and indicate differences in neural reinforcement sensitivity are a promising ADHD prognostic biomarker.

Burst-pause criterion derivation for drinkometer measurements of ingestive behavior.

The drinkometer is a promising device for the study of ingestive behavior of liquid meals in humans. It can be used to investigate behavior in different target populations. However, ingestive behavior has a great variability across study participants. Therefore, a new analytical approach is required for the extraction and analysis of drinkometer-derived data that could account for this variability. We developed an optimized protocol to predict an optimal burst-pause criterion (PC) for the extraction of PC-dependent microstructural parameters of ingestive behavior. These describe the microstructure of bursts, while PC-independent parameters describe the microstructure of sucks. Therefore, a PC is required to analyze separately two physiologically different parts of behavior. To accomplish this burst-pause criterion derivation (BPCD), a Gaussian Mixture Model (GMM) was built for estimation of two probability density functions (PDFs). These model the distribution of inter-suck intervals (ISIs) and inter-burst intervals (IBIs), respectively. The PC is defined at the intersection point of the two density functions. A Kaplan-Meier (KM) survival analysis was performed for post-hoc verification of the fit of the predicted optimal PC to the ISI distribution. In this protocol paper, we present a walkthrough of the data analysis of drinkometer-derived data for the measurement of microstructure of ingestive behavior based on previous results published by our group [1].•Standardization of the burst-pause criterion derivation for drinkometer measurements of ingestive behavior.•All codes are publicly available in a repository.•The method can be easily adapted to studies with larger sample size or more than one study stimulus.

The Role of Impulsivity and Reward Deficiency in "Liking" and "Wanting" of Potentially Problematic Behaviors and Substance Uses.

A few studies have examined the changes in substance- and behavior-related "wanting" and "liking" of human subjects, the key properties of Incentive Sensitization Theory (IST). The aim of this study was to examine the dissociation between "wanting" and "liking" as a function of usage frequency, intensity, and subjective severity in individuals across four substances (alcohol, nicotine, cannabis, and other drugs) and ten behaviors (gambling, overeating, gaming, pornography use, sex, social media use, Internet use, TV-series watching, shopping, and work). Also, the potential roles of impulsivity and reward deficiency were investigated in "wanting," "liking," and wellbeing. The sex differences between "wanting" and "liking" were also examined. Based on our findings using structural equation modeling with 749 participants (503 women, M age = 35.7 years, SD = 11.84), who completed self-report questionnaires, "wanting" increased with the severity, frequency, and intensity of potentially problematic use, while "liking" did not change. Impulsivity positively predicted "wanting," and "wanting" positively predicted problem uses/behaviors. Reward deficiency positively predicted problem uses/behaviors, and both impulsivity and problem uses/behaviors negatively predicted wellbeing. Finally, women showed higher levels of "wanting," compared to men. These findings demonstrate the potential roles of incentive sensitization in both potentially problematic substance uses and behaviors.

Association between microstructure of ingestive behavior and body weight loss in patients one year after Roux-en-Y gastric bypass.

Roux-en-Y gastric bypass (RYGB) is one of the most effective procedures in the treatment of obesity. However, the predictive value of the microstructure of ingestion has not been widely investigated in this context. Here, we applied a recently developed drinkometer device to analyze the microstructure of ingestive behavior during a liquid meal in women and investigate whether it correlated with measures of weight loss after RYGB. Macro- and microstructural parameters of ingestive behavior of female patients (n = 24) one year after RYGB were measured in two different test sessions within a period of two weeks using the drinkometer. A Pearson correlation analysis was performed to compare the macro- and microstructural parameters of ingestive behavior with the percentage of total weight loss (%TWL), percentage excess BMI loss (%EBMIL), and body mass index (BMI) one year after RYGB, as well as age. A Bonferroni adjusted p < 0.003 was considered significant for the correlation analysis. For all other statistical tests, a p < 0.05 was considered significant. One year after surgery, a significant body weight loss was achieved in our study population (111.2 ± 15.6 kg vs 73.4 ± 11.7 kg; ***p < 0.001), with a mean%TWL of 33.8% (range: 20.4-48.6%). At the first test session,%TWL correlated with suck duration (r = 0.41, 0.05 > p > 0.003);%EBMIL correlated with both suck duration (r = 0.64, *p < 0.003) and inter-suck intervals (ISIs, r = -0.47, *p < 0.003), and, finally, BMI correlated with suck duration (r = 0.62, *p < 0.003) and ISIs (r = 0.48, *p < 0.003). However, at the second test session, no correlation was found between the body weight loss and the recorded ingestive parameters. Furthermore, no statistically significant difference was found in microstructural parameters of ingestive behavior between the two test sessions even though meal size decreased by 20% on the second visit (342.6.6 ± 167 kcal vs. 271.8 ± 142.8 kcal). A greater body weight loss of patients one year after surgery seems to be associated with longer suck duration and shorter ISIs, but only when the stimulus is tested for the first time by the study participants. This study contributes to the current knowledge about the ingestive behavior of bariatric patients one year after RYGB in terms of its association with the achieved weight loss. The use of the drinkometer device for the measurement of microstructure of ingestive behavior should be further expanded to different research questions and patient subgroups other than good responders. Its possible applications in clinical and behavioral research need to be included in the agenda of bariatric research.

Microstructural changes in human ingestive behavior after Roux-en-Y gastric bypass during liquid meals.

BACKGROUNDRoux-en-Y gastric bypass (RYGB) decreases energy intake and is, therefore, an effective treatment of obesity. The behavioral bases of the decreased calorie intake remain to be elucidated. We applied the methodology of microstructural analysis of meal intake to establish the behavioral features of ingestion in an effort to discern the various controls of feeding as a function of RYGB.METHODSThe ingestive microstructure of a standardized liquid meal in a cohort of 11 RYGB patients, in 10 patients with obesity, and in 10 healthy-weight adults was prospectively assessed from baseline to 1 year with a custom-designed drinkometer. Statistics were performed on log-transformed ratios of change from baseline so that each participant served as their own control, and proportional increases and decreases were numerically symmetrical. Data-driven (3 seconds) and additional burst pause criteria (1 and 5 seconds) were used.RESULTSAt baseline, the mean meal size (909.2 versus 557.6 kCal), burst size (28.8 versus 17.6 mL), and meal duration (433 versus 381 seconds) differed between RYGB patients and healthy-weight controls, whereas suck volume (5.2 versus 4.6 mL) and number of bursts (19.7 versus 20.1) were comparable. At 1 year, the ingestive differences between the RYGB and healthy-weight groups disappeared due to significantly decreased burst size (P = 0.008) and meal duration (P = 0.034) after RYGB. The first-minute intake also decreased after RYGB (P = 0.022).CONCLUSIONRYGB induced dynamic changes in ingestive behavior over the first postoperative year. While the eating pattern of controls remained stable, RYGB patients reduced their meal size by decreasing burst size and meal duration, suggesting that increased postingestive sensibility may mediate postbariatric ingestive behavior.TRIAL REGISTRATIONNCT03747445; https://clinicaltrials.gov/ct2/show/NCT03747445.FUNDINGThis work was supported by the University of Zurich, the Swiss National Fund (32003B_182309), and the Olga Mayenfisch Foundation. Bálint File was supported by the Hungarian Brain Research Program Grant (grant no. 2017-1.2.1-NKP-2017-00002).

Mental and emotional representations of "weight loss": free-word association networks in members of bariatric surgery-related social media communities.

BACKGROUND: Mindset and communication barriers may hinder the acceptance of bariatric surgery (BS) by the eligible patient population. OBJECTIVES: To improve the understanding of expectations, opinions, emotions, and attitudes toward weight loss among patients with obesity. SETTING: Switzerland, Germany, Austria. METHODS: Survey data collected from BS-related social media communities (n = 1482). Participants were asked to write 5 words that first came to their mind about "weight loss," and to select 2 emotions, which best described their corresponding feelings. Demographic and obesity-related data were collected. Cognitive representations were constructed based on the co-occurrence network of associations, using validated data-driven methodology. RESULTS: Respondents were Caucasian (98%), female (94%), aged 42.5 ± 10.1 years, current/highest lifetime body mass index = 36.9 ± 9/50.7 ± 8.7 kg/m2. The association network analysis revealed the following 2 cognitive modules: benefit-focused (health, attractiveness, happiness, agility) and procedure-focused (effort, diet, sport, surgery). Patients willing to undergo BS were more benefit-focused (odds ratio [OR] = 2.4, P = .02) and expressed more "hope" (OR = 142, P < .001). History of BS was associated with higher adherence to the procedure-focused module (OR = 2.3, P < .001), and with increased use of the emotions "gratitude" (OR = 107, P < .001), "pride" (OR = 15, P < .001), and decreased mention of "hope" (OR = .03, P < .001). CONCLUSION: Patients with obesity in our study tend to think about weight loss along 2 cognitive schemes, either emphasizing its expected benefits or focusing on the process of achieving it. Benefit-focused respondents were more likely to consider BS, and to express hope rather than gratitude or pride. Novel communication strategies may increase the acceptance of BS by incorporating weight loss-related cognitive and emotional content stemming from patients' free associations.

Reorganization of Large-Scale Functional Networks During Low-Frequency Electrical Stimulation of the Cortical Surface.

We investigated the functional network reorganization caused by low-frequency electrical stimulation (LFES) of human brain cortical surface. Intracranial EEG data from subdural grid positions were analyzed in 16 pre-surgery epileptic patients. LFES was performed by injecting current pulses (10mA, 0.2ms pulse width, 0.5Hz, 25 trials) into all adjacent electrode contacts. Dynamic functional connectivity analysis was carried out on two frequency bands (low: 1-4Hz; high: 10-40Hz) to investigate the early, high frequency and late, low frequency responses elicited by the stimulation. The centralization increased in early compared to late responses, suggesting a more prominent role of direct neural links between primarily activated areas and distant brain regions. Injecting the current into the seizure onset zone (SOZ) evoked a more integrated functional topology during the early (N1) period of the response, whereas during the late (N2) period - regardless of the stimulation site - the connectedness of the SOZ was elevated compared to the non-SOZ tissue. The abnormal behavior of the epileptic sub-network during both part of the responses supports the idea of the pathogenic role of impaired inhibition and excitation mechanisms in epilepsy.

Drinking microstructure in humans: A proof of concept study of a novel drinkometer in healthy adults.

Microstructural analysis of ingestion provides valuable insight into the roles of chemosensory signals, nutritional content, postingestive events, and physiological state. Our aim was to develop a novel drinkometer for humans to measure detailed aspects of ingestion of an entire liquid meal or drinking session. The drinkometer records, in high definition (1 kHz), the weight of a fluid reservoir from which participants drink via a tube. An ultrasonic sensor measures the height of the fluid to derive density. Drinking speed over time can be displayed as a waveform. The smallest units of ingestion are sucks, which are organized in bursts. By applying probability density functions (PDF) on loge-transformed inter-suck intervals (ISI), an optimal burst-pause criterion (PC) can be identified. Information on ingestive volumes, rates, and durations can be then computed for the entire session, as well as for sucks and bursts. We performed a validation study on 12 healthy adults in overnight-fasted and in non-fasted states in 16 drinking sessions with 8 concentrations of sucrose (0-280 mM) presented in a blinded and random fashion. PDF determined PC = 2.9 s as optimal. Two-way RM-ANOVA revealed that total caloric intake during a drinking session depended on sucrose concentration (P < .001) and fasted state (P = .006); total drinking time (P < .001), total consumed volume (P = .003), number of sucks in total (P < .001), number of sucks per burst (P = .03), and burst duration (P = .02) were significantly influenced by fasting. In contrast, volume per suck (P = .002), suck speed (P < .001), and maximal speed per suck (P < .001) depended on sucrose concentration. We conclude that the novel drinkometer is able to detect differences in microstructural parameters of drinking behavior dependent on different motivational states, thus, adds to the technological toolbox used to explore human ingestive behavior.

Emergence of polarized opinions from free association networks.

We developed a method that can identify polarized public opinions by finding modules in a network of statistically related free word associations. Associations to the cue "migrant" were collected from two independent and comprehensive samples in Hungary (N1 = 505, N2 = 505). The co-occurrence-based relations of the free word associations reflected emotional similarity, and the modules of the association network were validated with well-established measures. The positive pole of the associations was gathered around the concept of "Refugees" who need help, whereas the negative pole associated asylum seekers with "Violence." The results were relatively consistent in the two independent samples. We demonstrated that analyzing the modular organization of association networks can be a tool for identifying the most important dimensions of public opinion about a relevant social issue without using predefined constructs.

Visual mismatch negativity (vMMN) for low- and high-level deviances: A control study.

The aim of our studies was to separate the effects of violating a sequential rule (genuine visual mismatch negativity; gvMMN) from the decreased activity in response to repeated stimuli (stimulus-specific adaptation; SSA) for simple and more complex stimuli. To accomplish this goal, different control procedures were applied with the aim of finding the correct control for vMMN studies. Event-related brain electric activity (ERPs) was measured in response to nonattended visual stimuli that were presented either in an oddball manner or in various control sequences. To identify the cortical sources of the different processes, the sLORETA inverse solution was applied to the average ERP time series. In Experiment 1, the stimuli were line textures, and the deviancy was different line orientations. SSA fully explained the deviant-related ERP effects (increased posterior negativity in the 105-190 ms range). In Experiments 2 and 3, windmill patterns were used. Infrequent windmill patterns with 12 vanes elicited gvMMN (posterior negativities in the 100-200 and 200-340 ms ranges), whereas in the case of the less complex (six vanes) stimuli, SSA explained the negative deflection in both latency ranges (178-216 and 270-346 ms). In Experiment 3, infrequent stimuli with six vanes elicited deviant-related posterior negativity within the sequence of less complex (four vanes) frequent patterns. We reconcile the discrepant results by proposing that the underlying processes of vMMN are not uniform but depend strongly on the eliciting stimulus and that the complexity difference between the infrequent and frequent stimuli has considerable influence on the deviant-related response.

Age-dependent characteristics of feedback evaluation related to monetary gains and losses.

Monitoring the consequences of actions is of crucial importance in order to optimize behavior to the challenges of the environment. Recently the age-related aspects of this fundamentally important cognitive processing have been brought into the focus of investigation since behavioral monitoring and related control mechanisms are widely known to be affected by aging. Processing of feedback stimuli is a core mechanism for rapid evaluation of the functionally significant aspects of outcome, guiding behavior towards avoidance or approach. The aim of the present study was to analyze the age-related alterations in the most prominent electrophysiological correlates of feedback processing, the feedback-related negativity (FRN) and the P3 event-related potential components, using a two-choice-single-outcome gambling task with two amounts of monetary stakes. In terms of behavioral indices higher proportion of risky choices was observed after loss than after gain events in both groups. In the young the FRN component was found to be an indicator of the goodness of outcome (loss or gain), and the P3 showed a complex picture of feedback evaluation with selective sensitivity to large amount of gain. In contrast, in the elderly group outcome valence had no effect on the amplitude of the FRN, and the P3 was also insensitive of the complex outcome properties. As the ERP-correlates of feedback processing are not as pronounced in the elderly, it is suggested that normal aging is accompanied by an alteration of the neural mechanisms signaling the most salient feedback stimulus properties.

Social Representations of Hero and Everyday Hero: A Network Study from Representative Samples.

The psychological investigation of heroism is relatively new. At this stage, inductive methods can shed light on its main aspects. Therefore, we examined the social representations of Hero and Everyday Hero by collecting word associations from two separate representative samples in Hungary. We constructed two networks from these word associations. The results show that the social representation of Hero is more centralized and it cannot be divided into smaller units. The network of Everyday Hero is divided into five units and the significance moves from abstract hero characteristics to concrete social roles and occupations exhibiting pro-social values. We also created networks from the common associations of Hero and Everyday Hero. The structures of these networks show a moderate similarity and the connections are more balanced in case of Everyday Hero. While heroism in general can be the source of inspiration, the promotion of everyday heroism can be more successful in encouraging ordinary people to recognize their own potential for heroic behavior.

Age-related characteristics of risky decision-making and progressive expectation formation.

During daily encounters, it is inevitable that people take risks. Investigating the sequential processing of risk hazards involve expectation formation about outcome contingencies. The present study aimed to explore risk behavior and its neural correlates in sequences of decision making, particularly in old age, which represents a critical period regarding risk-taking propensity. The Balloon Analogue Risk Task was used in an electrophysiological setting with young and elderly age groups. During the task each additional pump on a virtual balloon increased the likelihood of a balloon burst but also increased the chance to collect more reward. Event-related potentials associated with rewarding feedback were analyzed based on the forthcoming decisions (whether to continue or to stop) in order to differentiate between states of expectation towards gain or loss. In the young, the reward positivity ERP component increased as a function of reward contingencies with the largest amplitude for rewarding feedback followed by the decision to stop. In the elderly, however, reward positivity did not reflect the effect of reward structure. Behavioral indices of risk-taking propensity suggest that the performance of the young and the elderly were dissociable only with respect to response times: The elderly was characterized by hesitation and more deliberative decision making throughout the experiment. These findings signify that sequential tracking of outcome contingencies has a key role in cost-efficient action planning and progressive expectation formation.

Frontal midline theta connectivity is related to efficiency of WM maintenance and is affected by aging.

Representations in working memory (WM) are temporary, but can be refreshed for longer periods of time through maintenance mechanisms, thereby establishing their availability for subsequent memory tests. Frontal brain regions supporting WM maintenance operations undergo anatomical and functional changes with advancing age, leading to age related decline of memory functions. The present study focused on age-related functional connectivity changes of the frontal midline (FM) cortex in the theta band (4-8 Hz), related to WM maintenance. In the visual delayed-match-to-sample WM task young (18-26 years, N=20) and elderly (60-71 years N=16) adults had to memorize sample stimuli consisting of 3 or 5 items while 33 channel EEG recording was performed. The phase lag index was used to quantify connectivity strength between cortical regions. The low and high memory demanding WM maintenance periods were classified based on whether they were successfully maintained (remembered) or unsuccessfully maintained (unrecognized later). In the elderly reduced connectivity strength of FM brain region and decreased performance were observed. The connectivity strength between FM and posterior sensory cortices was shown to be sensitive to both increased memory demands and memory performance regardless of age. The coupling of frontal regions (midline and lateral) and FM-temporal cortices characterized successfully maintained trials and declined with advancing age. The findings provide evidence that a FM neural circuit of theta oscillations that serves a possible basis of active maintenance process is especially vulnerable to aging.

EEG network connectivity changes in mild cognitive impairment - Preliminary results.

Resting state EEGs were compared between patients with amnestic subtype of mild cognitive impairment (aMCI) and matched elderly controls at two times over a one year period. The study aimed at investigating the role of functional connectivity between and within different brain regions in relation to the progression of cognitive deficit in MCI. The EEG was recorded in two sessions during eyes closed and eyes open resting conditions. Functional brain connectivity was investigated based on the measurement of phase synchronization in different frequency bands. Delta and theta synchronization characteristics indicated decreased level of local and large-scale connectivity in the patients within the frontal, between the frontal and temporal, and frontal and parietal brain areas which was more pronounced 1year later. As a consequence of opening the eyes connectivity in the alpha1 band within the parietal lobe decreased compared to the eyes closed condition but only in the control group. The lack of alpha1 band reactivity following eye opening could reliably differentiate patients from controls. Our preliminary results support the notion that the functional disconnection between distant brain areas is a characteristic feature of MCI, and may prove to be predictive in terms of the progression of this condition.

[Spectral, phase-synchronization, and graph theoretical EEG changes related to mental arithmetics]. / Számolási teljesítmeny spektrális, fázisszinkronizációs és gráfelméleti EEG-jellemzoi.

During mental arithmetic operations working memory plays an important role, but there are only few studies in which an attempt was made to separate this effect from the process of arithmetics per se. In this study the effects of arithmetic on the EEG of young adults (14 participants, six of them women, mean age 21.57 years, SD: 2.62) was investigated during a subtraction task in the theta (4-8 Hz) frequency band. Besides the power density spectrum analysis phase synchrony based on recently developed graph theoretical methods were used and strength of local connections (cluster coefficient; C) and global interconnectedness of network (characteristic path length; L) were determined. Before the arithmetic task passive viewing (control situation) and a number recognition paradigms were used. During the arithmetic task compared to the control situation significantly increasing phase synchrony and C values were found. L was significantly shorter (F(2, 26) = 818.77, p < 0.0001) only during the arithmetic task: this fact and the former two results imply that the network topology shifted towards the "small world" direction. Our findings concerning regional differences confirm those reported earlier in the literature: compared to the control condition significant task-related increase was found in C values in the parietal areas [more explicitly in the left side, (F(1, 13) = 7.2020, p = 0.0188)], which probably corresponds to stronger local connections and more synchronized (sub)networks. During the task condition significantly increased 0 band power; (F(1, 13) = 7.9708, p = 0.01447 and decreased L values were found in the left frontal region compared to the right side (F(1, 13) = 6.0734, p = 0.0284), which can also be interpreted as an indicator of optimized network topology of information processing.