Tyrosine ameliorates heat induced delay in event related potential P300 and contingent negative variation

The efficacy of tyrosine, a catecholamine precursor, as a countermeasure in the reduction of cognitive decline during heat exposure (HE) using event-related potential P300, and contingent negative variation (CNV) was evaluated. Ten healthy males, age 20–30 years participated in the study. Volunteers received placebo or tyrosine (6.5 g) 90 min prior to HE (1.5 h in 45 °C + 30% RH). P300 latency was significantly increased (p < 0.01) during exposure with placebo, which was reduced significantly (p < 0.01) after tyrosine supplementation. There was an increase in CNV M100 latency (p < 0.05) and reaction time (p < 0.01) and decrease in M100 amplitude (p < 0.01) during HE with placebo, which returns to near normal level with the tyrosine administration. A significantly higher plasma norepinephrine (p < 0.05), dopamine and epinephrine levels were detected in tyrosine supplemented group post heat exposure. HE increases the brain catecholamine activity thereby reduces the plasma norepinephrine and dopamine level leading to a reduction in cognitive performances. Tyrosine supplementation increases the catecholamine level and reduces the impairment of cognitive performance during HE.     

The anticipatory potential (contingent negative variation) as an indicator of neuronal information processing in relation to changes in slow potentials in the EEG

The aim of this study was to investigate the interaction between spontaneous Slow Potential Shifts (SPSs) and the probability effect on CNV amplitudes. Fifteen right-handed volunteers participated in this experiment. The presentation of the stimuli was triggered by spontaneous SPSs (duration: 2 seconds, mean-amplitude: 10 microV) in the EEG signal at Cz. Thus, two different S1s (S1a: 1500 Hz, S1b: 2000 Hz) were presented in a random order with a fixed probability of occurrence of 0.8 for S1a and 0.2 for S1b. Each S1 was followed by a light stimulus (S2) with a constant ISI of 4 seconds. According to the cue, the subjects had to push the left (S1a) or the right (S1b) response button as fast as possible with their right index finger. The order of the 4 experimental conditions (stimulus presentation triggered by negative or positive shifts and recording of negative or positive shifts without any stimuli) in which each subject participated was balanced across subjects. Several significant effects could be found by means of a two-way ANOVA for repeated measures (condition x recording site): Negative shifts were accompanied by smaller CNVs as well as PINVs (resolution deficits) at all recording sites; the probability effect was found to be significant in the positive shift condition at F3, F4, and Cz, but not in the negative shift condition except at Cz for the E-wave. CNVs triggered by negative shifts only showed a significant correlation (-.55) with reaction time. These results together favor a two-component model suggesting that SPSs, spontaneous and evoked, are largely generated by glia depolarization, which is evoked by but outlasts neuronal activity.     

The contingent negative variation laterality and dynamics in antisaccade task in normal and unmedicated schizophrenic subjects

Contingent negative variation (CNV) topography, hemispheric asymmetry and time-course were investigated in healthy subjects and non-medicated paranoid schizophrenic patients in two antisaccade paradigms with the short (800-1000 ms) and long (1200-1400 ms) durations of the fixation period. EEG and electrooculogram (EOG) were recorded. Saccade characteristics and mean amplitudes of slow cortical potentials time-locked to peripheral target were analyzed in 23 healthy volunteers and 19 schizophrenic patients. Compared to healthy control subjects, schizophrenic patients had significantly slower antisaccades and committed significantly more erroneous saccades in the both antisaccade tasks. The prolongation of the fixation period resulted in noticeable decrease of error percent in patients group. The analysis of CNV time-course has revealed two distinct stages in both groups. The early CNV stage was represented by a negative wave with the maximal amplitude over midline fronto-central area, and the late stage was characterized by increased CNV amplitude at the midline and left parietal electrode sites. In healthy subjects the simultaneous activation of frontal and parietal areas was observed in the paradigm with the shorter fixation interval; the increase of the fixation period produced consecutive activation of these areas. Schizophrenic patients' CNV amplitude was generally smaller than that of healthy subjects. The most pronounced between-group differences of the negative shift amplitude were revealed at frontal electrode sites during the early CNV stage in both modifications of the antisaccade task. The deficit of frontal activation revealed in patients at the early stage of antisaccade preparatory set in both antisaccadic paradigms may be related to pathogenesis of paranoid schizophrenia.     

Response speed, contingent negative variation and P300 in Alzheimer’s disease and MCI

Background

Decreased speed of information processing is a hallmark of Alzheimer’s disease (AD) and mild cognitive impairment (MCI). Recent studies suggest that response speed (RS) measures are very sensitive indicators of changes in longitudinal follow-up studies. Insight into the psycho-physiological underpinnings of slowed RS can be provided by measuring the associated event-related potentials (ERP).

Aims

The current study aims to investigate the relation between RS and its psycho-physiological correlates in AD and MCI.

Methods

Fifteen psychoactive drug-naïve AD patients, 20 MCI patients and twenty age-matched, healthy control subjects participated. Response speed was measured during a simple (SRT) and choice reaction time task (CRT). An oddball and contingent negative variation (CNV) paradigm were used to elicit ERP. To evaluate test-retest reliability (TRR), subjects underwent a similar assessment one week after the first.

Results

The SRT and CRT distinguished the patient groups significantly. The P300 amplitude and latency also distinguished the groups and showed a significant correlation with response speed. The CNV amplitude did not reveal a significant difference between groups and also showed a low TRR.The TRR of the SRT, CRT and P300 amplitude and latency in general was moderate to high.The current study suggests that response speed measures on a behavioural and psycho-physiological level deserve attention as a possible marker in the diagnosis and follow-up of AD.     

Differences in EEG alpha activity related to giftedness

In three experiments, differences in EEG alpha activity between gifted (mean IQ = 137) and average (mean IQ = 105) individuals were investigated. EEG activity was monitored over 16 scalp locations. A fast Fourier transform was performed on 15 artifact-free 2-second chunks of data to derive a spectral power average in the alpha band (7.5–13 Hz). In the first experiment, EEG of gifted and average individuals during two relaxation phases—eyes closed and eyes open—was recorded. Gifted individuals showed higher EEG alpha power only while resting with eyes open. In the second experiment, gifted and average individuals solved two problems that were divided into phases of problem solving and preparing for problem solving (reading, making a plan of how to solve the problem). Significant differences were obtained only for the problem-solving stages. Gifted individuals in comparison with average ones showed higher alpha power (less mental effort) while solving the two problems. The third experiment investigated whether the lower mental activity displayed by gifted individuals was related to their ability to form more abstract schemata. For that purpose EEG was recorded while gifted and average individuals memorized lists of words and pictures that either allowed, or did not allow, for classification into more abstract categories. For both types of lists, gifted individuals displayed higher alpha power than average ones. The results obtained confirm the hypothesis that the higher EEG alpha power during information processing displayed by gifted individuals may derive from the nonuse of many brain areas not required for the problem at hand.     

Cultural differences related to positive and negative valence

Differences between North American and East Asian cultures were examined in terms of the valence of psychological constructs. Americans were more likely than Japanese to focus on positive things. In contrast, Japanese ( vs Americans) were more likely to attend to negative information of the self, but not more or less likely to focus on negative things about others. Based on within-culture analyses, the Americans' data were better described by their tendency to focus on positive things over negative things than by their tendency for self-enhancement. In contrast, the Japanese data were better described by their self-critical tendency. This result was replicated in a second study. In addition, correlations between constructs with opposite valences were negative in the USA, but positive or absent in Japan.     

关联负变化(CNV)与反应时的关系

本实验采用选择性叠加方法,研究了关联负变化(Contingent NegativVariation以下简称CNV)与反应时的关系。证明:最长、最短反应时差异显著时,相对应的CNV面积差异也显著。CNV的这种差异主要表现在CNV面积的后半部分。对形成这种现象的原因作了讨论。     

Psychopathy is related to negative affectivity but not to anxiety sensitivity

Although the hypothesis that psychopathic individuals are characterized by a reduced capacity for experiencing anxiety is central to many theories of psychopathy, most prior studies have examined anxiety and fear measures generally considered outdated in the literature. Moreover, prior findings are mixed, with several studies reporting no relationships between psychopathy and anxiety, and others suggesting negative relationships for the affective, interpersonal aspects of the disorder and positive relationships for the antisocial behavior dimension. To examine whether psychopathy dimensions are associated with contemporary measures of anxiety, the Anxiety Sensitivity Index and State Trait Anxiety Inventory-Trait scale were administered to 157 male inmates. Participants also completed the MMPI-derived Welsh Anxiety Scale (WAS), commonly used in psychopathy studies. Analyses provide no evidence for a negative relationship between psychopathy's affective, interpersonal factor and anxiety sensitivity after controlling for trait anxiety. Trait anxiety and WAS scores were positively associated with the antisocial behavior dimension of psychopathy. Findings do replicate prior relationships between the WAS and psychopathy, suggesting the WAS may measure aspects of negative affectivity that differ from anxiety.     

Individual Differences in Children (Book)

This study involved a comparison of the factor structure of the MCMI in: a general psychiatric sample, a substance misuse sample, and a drug misuse sample. Examination of the factor matrices for the three clinical samples provided evidence for a sturdy factor measuring a negativistic-avoidant personality style with associated anxiety, depression, and somatization. Evidence was also available in all three samples for factors measuring: a) a paranoid cognitive and interpersonal pattern, and b) an asocial-avoidant personal orientation.     

Differences between traces of negative emotions in smile judgment

While a smile can reflect felt happiness, it can also be voluntarily produced, for instance, to mask negative emotions. Masking strategies are not always perfect and traces of the negative emotion can leak. The current study examined the role of traces of anger, sadness, fear and disgust in the judgment of authenticity of smiles. Participants judged the authenticity of the smiles while their eye movements were recorded. They were also asked if the stimuli comprised another emotion and, if so, what the emotion was. Results revealed that participants were sensitive to traces of negative emotions. Variations were observed between emotions with performance being best for traces of fear and lowest for traces of anger in the eyebrows in the judgment task. However, when the presence of a negative emotion was reported, participants were less accurate in identifying fear but more accurate in identifying anger. Furthermore, variations were observed as a function of the location of the trace whether in the mouth or eyes as a function of the emotion. Traces in the eyebrows were associated with better performance than traces in the mouth for sadness but the opposite was observed for anger. The performance at the judgment task was not linked to eye movement measures or explicit knowledge of the masked emotion. Future research should explore other explanation for the variations in performance in the judgments of authenticity of masking smiles such as emotional contagion.     

Receipt of negative feedback is related to increased negative feedback seeking among individuals with depressive symptoms

In recent years, numerous studies have demonstrated a link between positive and negative feedback seeking by depressed individuals, interpersonal rejection, and depression chronicity. Nonetheless, many of the specific interpersonal patterns underlying these links have yet to be clearly specified. One important lingering question concerns how depressed individuals respond to negative evaluation or feedback from others, because continued negative feedback seeking could place depressed people at risk for further rejection and continuation/exacerbation of depressive symptoms. Two studies were conducted to investigate the influence of negative feedback provisions from others on the feedback seeking behaviors of individuals with depressive symptoms. The results from Study 1 indicated an increased tendency to seek negative feedback among depressive individuals in association with an independent negative evaluation by their college roommates. Using a sample of newlywed couples, Study 2 extended this finding by demonstrating that, when directly provided with negative feedback from their spouses, individuals with depressive symptomatology actively sought further negative feedback, while those without such symptoms did not. Together, the results from these studies suggest that depressed individuals are likely to respond to negative evaluation and feedback from others with behaviors that could place them at risk for further rejection and continuing, if not worsening problems with depression.     

Chimpanzee (Pan troglodytes) intentional communication is not contingent upon food

Studies of great apes have revealed that they use manual gestures and other signals to communicate about distal objects. There is also evidence that chimpanzees modify the types of communicative signals they use depending on the attentional state of a human communicative partner. The majority of previous studies have involved chimpanzees requesting food items from a human experimenter. Here, these same communicative behaviors are reported in chimpanzees requesting a tool from a human observer. In this study, captive chimpanzees were found to gesture, vocalize, and display more often when the experimenter had a tool than when she did not. It was also found that chimpanzees responded differentially based on the attentional state of a human experimenter, and when given the wrong tool persisted in their communicative efforts. Implications for the referential and intentional nature of chimpanzee communicative signaling are discussed.     

Antonovsky's sense of coherence scale related to negative and positive affectivity

The Sense of Coherence (SOC) Scale purports to measure a disposition which engenders, sustains, and enhances health. However, reports of high negative correlations (average about −0.7) with negative affectivity (NA) measures raise doubt as to whether it does not only measure the absence of neuroticism. These relationships could also be interpreted as validation of the scale, if the low end of NA is conceived as emotional stability. In samples of nursing students, managerial and administrative personnel and life insurance consultants, the SOC scale related negatively to NA scales, and positively to positive affectivity scales, but more strongly to NA. An emotional stability scale correlated positively with the SOC scale, supporting the alternative interpretation. Stepwise multiple-regression analyses confirmed the bivariate findings but also indicated that from 25 to 47 per cent of SOC variability remained unexplained after the trait scales' predictions. The SOC appears to be a highly complex construct which partakes in a mixture of personality domains, and is taxonomically above the trait level. © 1998 John Wiley & Sons, Ltd.