Maksymilian Bielecki

Learning-Dependent Plasticity of the Barrel Cortex Is Impaired by Restricting GABA-Ergic Transmission

Experience-induced plastic changes in the cerebral cortex are accompanied by alterations in excitatory and inhibitory transmission. Increased excitatory drive, necessary for plasticity, precedes the occurrence of plastic change, while decreased inhibitory signaling often facilitates plasticity. However, an increase of inhibitory interactions was noted in some instances of experience-dependent changes. We previously reported an increase in the number of inhibitory markers in the barrel cortex of mice after fear conditioning engaging vibrissae, observed concurrently with enlargement of the cortical representational area of the row of vibrissae receiving conditioned stimulus (CS). We also observed that an increase of GABA level accompanied the conditioning. Here, to find whether unaltered GABAergic signaling is necessary for learning-dependent rewiring in the murine barrel cortex, we locally decreased GABA production in the barrel cortex or reduced transmission through GABAA receptors (GABAARs) at the time of the conditioning. Injections of 3-mercaptopropionic acid (3-MPA), an inhibitor of glutamic acid decarboxylase (GAD), into the barrel cortex prevented learning-induced enlargement of the conditioned vibrissae representation. A similar effect was observed after injection of gabazine, an antagonist of GABAARs. At the behavioral level, consistent conditioned response (cessation of head movements in response to CS) was impaired. These results show that appropriate functioning of the GABAergic system is required for both manifestation of functional cortical representation plasticity and for the development of a conditioned response.

Effect of Frustration on Brain Activation Pattern in Subjects with Different Temperament

In spite of the prevalence of frustration in everyday life, very few neuroimaging studies were focused on this emotional state. In the current study we aimed to examine effects of frustration on brain activity while performing a well-learned task in participants with low and high tolerance for arousal. Prior to the functional magnetic resonance imaging session, the subjects underwent 2 weeks of Braille reading training. Frustration induction was obtained by using a novel highly difficult tactile task based on discrimination of Braille-like raised dots patterns and negative feedback. Effectiveness of this procedure has been confirmed in a pilot study using galvanic skin response and questionnaires. Brain activation pattern during tactile discrimination task before and after frustration were compared directly. Results revealed changes in brain activity in structures mostly reported in acute stress studies: striatum, cingulate cortex, insula, middle frontal gyrus and precuneus and in structures engaged in tactile Braille discrimination: SI and SII. Temperament type affected activation pattern. Subjects with low tolerance for arousal showed higher activation in the posterior cingulate gyrus, precuneus, and inferior parietal lobule than high reactivity group. Even though performance in the discrimination trials following frustration was unaltered, we observed increased activity of primary and secondary somatosensory cortex processing the tactile information. We interpret this effect as an indicator of additional involvement required to counteract the effects of frustration.

Prevalence and impact of autoimmune thyroid disease on myasthenia gravis course

Autoimmune thyroid diseases (ATDs) frequently accompany myasthenia gravis (MG) and may influence its course. We aimed to determine the association and impact of ATD with early‐ (<50 years), late‐onset MG, or thymoma‐MG.

Assessment of systemic and pulmonary arterial remodelling in women with systemic sclerosis.

Objectives: Systemic sclerosis (SSc) leads to pulmonary circulation dysfunctionand there are some indications of systemic circulation impairment. We evaluated the influence of SSc on the elastic properties of large systemic arterial walls and potential correlations between systemic and pulmonary circulation involvement. Method: We examined 75 consecutive women (mean age 53.13 ± 10.1 years) with confirmed SSc [mean disease duration (DD) 7.1 ± 9.1 years] and 21 age-matched female volunteers (mean age 52.6 ± 8.3 years, ns). Pulse wave velocity (PWV) and transthoracic echocardiography were performed. SSc patients were divided into two groups according to the median of DD: ≤ 3 years (39 patients) and > 3 years (36 patients). Results: Patients with DD > 3 years had higher PWV than those with DD ≤ 3 years and controls (log PWV: 2.23 ± 0.23 vs. 2.13 ± 0.16 and vs. 2.11 ± 0.16 m/s; p = 0.028 and 0.029, respectively). In addition, echocardiographic indices showed impaired right ventricular (RV) function in the patients with DD > 3 years. Also in these SSc patients, PWV correlated with clinical and echocardiographic parameters of pulmonary circulation: age (r = 0.64, p < 0.0001), acceleration time of pulmonary ejection (AcT; r = −0.38, p = 0.021), and tricuspid regurgitation peak gradient (TRPG; r = 0.34, p = 0.04). Multiple linear regression analysis showed that PWV was independently associated with DD (β = 0.22, p = = 0.02), AcT (β = −0.215, p = 0.03), and age (β = 0.44, p < 0.001). Conclusions: In patients with SSc lasting more than 3 years, the disease is characterized by increased stiffness of the large systemic arteries. Longer duration of SSc leads simultaneously to the increased stiffness of the large systemic arteries and to the progressive impairment of RV function and its coupling to the pulmonary arterial bed.

The effects of virtual experience on attitudes toward real brands.

Although the commercial availability and implementation of virtual reality interfaces has seen rapid growth in recent years, little research has been conducted on the potential for virtual reality to affect consumer behavior. One unaddressed issue is how our real world attitudes are affected when we have a virtual experience with the target of those attitudes. This study compared participant (N=60) attitudes toward car brands before and after a virtual test drive of those cars was provided. Results indicated that attitudes toward test brands changed after experience with virtual representations of those brands. Furthermore, manipulation of the quality of this experience (in this case modification of driving difficulty) was reflected in the direction of attitude change. We discuss these results in the context of the associative-propositional evaluation model.

Deadly Attraction – Attentional Bias toward Preferred Cigarette Brand in Smokers

Numerous studies have shown that biases in visual attention might be evoked by affective and personally relevant stimuli, for example addiction-related objects. Despite the fact that addiction is often linked to specific products and systematic purchase behaviors, no studies focused directly on the existence of bias evoked by brands. Smokers are characterized by high levels of brand loyalty and everyday contact with cigarette packaging. Using the incentive-salience mechanism as a theoretical framework, we hypothesized that this group might exhibit a bias toward the preferred cigarette brand. In our study, a group of smokers (N = 40) performed a dot probe task while their eye movements were recorded. In every trial a pair of pictures was presented – each of them showed a single cigarette pack. The visual properties of stimuli were carefully controlled, so branding information was the key factor affecting subjects’ reactions. For each participant, we compared gaze behavior related to the preferred vs. other brands. The analyses revealed no attentional bias in the early, orienting phase of the stimulus processing and strong differences in maintenance and disengagement. Participants spent more time looking at the preferred cigarettes and saccades starting at the preferred brand location had longer latencies. In sum, our data shows that attentional bias toward brands might be found in situations not involving choice or decision making. These results provide important insights into the mechanisms of formation and maintenance of attentional biases to stimuli of personal relevance and might serve as a first step toward developing new attitude measurement techniques.

Age-Related Changes in Resting-State EEG Activity in Attention Deficit/Hyperactivity Disorder: A Cross-Sectional Study

Numerous studies indicate that attention deficit/hyperactivity disorder (ADHD) is related to some developmental trends, as its symptoms change widely over time. Nevertheless, the etiology of this phenomenon remains ambiguous. There is a disagreement whether ADHD is related to deviations in brain development or to a delay in brain maturation. The model of deviated brain development suggests that the ADHD brain matures in a fundamentally different way, and does not reach normal maturity at any developmental stage. On the contrary, the delayed brain maturation model assumes that the ADHD brain indeed matures in a different, delayed way in comparison to healthy age-matched controls, yet eventually reaches proper maturation. We investigated age-related changes in resting-state EEG activity to find evidence to support one of the alternative models. A total of 141 children and teenagers participated in the study; 67 diagnosed with ADHD and 74 healthy controls. The absolute power of delta, theta, alpha, and beta frequency bands was analyzed. We observed a significant developmental pattern of decreasing absolute EEG power in both groups. Nonetheless, ADHD was characterized by consistently lower absolute EGG power, mostly in the theta frequency band, in comparison to healthy controls. Our results are in line with the deviant brain maturation theory of ADHD, as the observed effects of age-related changes in EEG power are parallel but different in the two groups.

Prognostic value of perioperative assessment of plasma cardiac troponin I in patients undergoing liver transplantation

An elevation in plasma cardiac troponins is an indicator of increased perioperative risk in orthopaedic and vascular surgery, however, data on liver transplantation (LTx) are scarce. The aim of the study was to evaluate the prevalence of cardiac troponin I (cTnI) elevation in the perioperative period of LTx, and its potential relationship with 1-year mortality. MATERIAL AND METHODS Analysis included 79 patients with liver cirrhosis. During LTx all patients underwent hemodynamic measurements. cTnI level was determined before the operation, 24, 48 and 72 hours afterwards. One-year mortality was assessed. RESULTS 12.7% patients died, all during in-hospital period. cTnI level on day 1. was identified as the most promising marker of increased death risk with optimal cut-off value of 0.215 ng/mL (the sensitivity of 60.0%, specificity of 87.0%, positive predictive value of 40.0%, negative predictive value of 93.8%). The most important predictor of cTnI increase was the duration of the LTx procedure followed by amount of packed red blood cells transfused, basic stroke volume index, and cardiac output index. IN CONCLUSION value of cTnI level assessed 24 hours post-surgery was a reliable predictor of death following LTx with optimal cut-off value of 0.215 ng/mL. The surgery time was the most important predictor of cTnI elevation.

Real-time strategy video game experience and structural connectivity - A diffusion tensor imaging study

Experienced video game players exhibit superior performance in visuospatial cognition when compared to non‐players. However, very little is known about the relation between video game experience and structural brain plasticity. To address this issue, a direct comparison of the white matter brain structure in RTS (real time strategy) video game players (VGPs) and non‐players (NVGPs) was performed. We hypothesized that RTS experience can enhance connectivity within and between occipital and parietal regions, as these regions are likely to be involved in the spatial and visual abilities that are trained while playing RTS games. The possible influence of long‐term RTS game play experience on brain structural connections was investigated using diffusion tensor imaging (DTI) and a region of interest (ROI) approach in order to describe the experience‐related plasticity of white matter. Our results revealed significantly more total white matter connections between occipital and parietal areas and within occipital areas in RTS players compared to NVGPs. Additionally, the RTS group had an altered topological organization of their structural network, expressed in local efficiency within the occipito‐parietal subnetwork. Furthermore, the positive association between network metrics and time spent playing RTS games suggests a close relationship between extensive, long‐term RTS game play and neuroplastic changes. These results indicate that long‐term and extensive RTS game experience induces alterations along axons that link structures of the occipito‐parietal loop involved in spatial and visual processing.

Questionable validity of left ventricular hypertrophy cutoff values in morbidly and super-morbidly obese patients

Current diagnostic ECG criteria of left ventricular hypertrophy in obese patients are still lacking.