1,720,973 research outputs found
Heroin abusers’ performance on the Tower of London Test relates to the baseline EEG alpha2 mean frequency shifts
No full textPlanning function deficit is the most consistent finding in neuropsychological studies of heroin addicts. The performance on the Tower of London Test (TLT) correlated with the duration of daily heroin abuse (DDHA) in our previous study. Alpha2 mean frequency in anterior/central derivations was also predicted by DDHA in the same patient population. This retrospective study was undertaken in order to understand better the relationships between observed neurological deviations in heroin abusers. Thirty-three heroin addicts and 12 healthy males were evaluated with 14 neuropsychological tests and resting eyes-closed electroencephalography (EEG). Multivariate tests showed that performance on the difficult (five-move) problems of TLT was strongly predicted by the EEG alpha2 mean frequency shifts, and these relationships were generally mediated by chronic heroin length. However, post-hoc analyses at separate leads demonstrated that the relationships between cognitive variables and alpha2 mean frequencies in the left hemisphere were independent of chronic heroin effects, whereas elevation of alpha2 frequency in the right hemisphere was strongly predicted by chronic heroin intake length. The patients with extremely high alpha2 mean frequency at the left central region were especially prone to failure in TLT due to the inability of the hypothesized alpha2-generating network, which normally projects to the central and temporal derivations bilaterally and to the right posterior temporal derivation to function appropriately. Hence, it was concluded that planning dysfunction in heroin abusers is related to alpha2 mean frequency shifts predominantly at the central regions
EEG spectral power and mean frequencies in early heroin abstinence
No full textThe purpose of the present study was to investigate cumulative heroin effects on brain functioning by studying relationships between EEG spectral power and mean frequencies and heroin abusing history. Eyes closed resting EEG data were collected from the 19 monopolar electrode sites in 33 heroin abusers and 13 age-matched healthy volunteers. The mean age of the patients was 23.1±4.5, the duration of daily heroin abuse (DDHA) ranged from 4 to 44 months, the i.v. doses of heroin ranged from 0.04 to 1.00 g/day, the abstinence length ranged from 6 days to 4.5 months. GLM repeated measures procedure revealed a significant group effect on the distribution of the mean power spectrum between bands and mean frequencies in almost all analyzed derivations. Further analysis demonstrated that these intergroup differences were diversely related to at least three aspects of heroin taking history. Frequency shifts in alpha2 range, most prominent in frontal and central derivations, were related to duration of daily heroin consumption. Slowing of alpha1 mean frequency, most prominent in central, temporal and occipital derivations, was registered mainly in heroin addicts who abused high doses of the drug. Spectral power characteristics of brain electrical activities in our patient population were strongly predicted by abstinence length. The present results give grounds to suppose that chronic heroin taking induces neuronal oscillation frequency changes, that may contribute to the development of antisocial trends and some semantic processes disturbances in these patients. Supplementary neurophysiological deficit is characteristic for heroin addicts, who takes high doses of the drug, however, its relation to heroin abusing remains unclear. Pronounced desynchronization is observed in acute heroin withdrawal, and spectral power characteristics tend to normalize almost completely during several weeks of abstinence
Single and combined effects of sympathetic and parasympathetic activity on perceptual sensitivity and attention
Get PDFPulse rate and cephalic pulse volume were recorded from 17 male and 37 female normal subjects during performance of an attentional task under high and low stress conditions. Verbal threshold (perceptual sensitivity) and word recognition (attention) were assessed using a visual verbal recognition task. Subjects were divided at the median for pulse rate and pulse volume during baseline, instruction, and task periods and grouped in terms of these two measures to represent different patterns of parasympathetic (vagal) and sympathetic activity. Analysis of variance was used to examine the effects of gender, stress condition, and autonomic pattern on autonomic activity, perceptual sensitivity, and attentional performance. Gender showed significant effects for pulse rate with higher scores for women during the instruction and task periods. High stress reduced perceptual sensitivity and resulted in better attentional performance. Whereas stress-induced sympathetic activity was related to low perceptual sensitivity and good attentional performance, high sympathetic in conjunction with low vagal baseline activity predicted relatively high perceptual sensitivity and poor attentional performance. Low or high baseline activity in both autonomic systems predicted low perceptual sensitivity and good attentional performance. Predictions of perception and attention can be improved by examining the effects of patterns of sympathetic and parasympathetic activity
Moods in everyday situations: Effects of menstrual cycle, work, and personality
Get PDFObjective: This study examined women’s moods on work and off days during different phases of the menstrual cycle. Method: Self-reports of the moods angry, happy, sad, stressed, tired, and anxious were obtained on two work and two off days during the luteal and follicular phases of the menstrual cycle in 203 nurses. Individual differences in anger expression, anxiety, and hostility were assessed. Results: Ratings of anxious, stressed, and tired were higher and happy and sad were lower on the workday than the off day. Menstrual cycle phase was associated with mood differences depending on the day (work, off work) and individual differences in personality traits. Conclusions: The experience of moods in everyday life is affected by overall levels of stress and phase of the menstrual cycle. The findings suggest the need to refine sociopsychobiological and clinical models of mood regulation and of risk for disease
Moods in everyday situations: Effects of menstrual cycle, work, and stress hormones
Get PDFObjective: This study examined women’s mood responsiveness on work and off days during different phases of the menstrual cycle. Methods: Self reports of negative, positive, and energy dimensions of mood were obtained throughout the day on two work and two off days during the luteal and follicular phases of the menstrual cycle in 203 women nurses. Individual differences in daytime and nighttime epinephrine, norepinephrine, and cortisol were assessed. Results: High daytime norepinephrine, epinephrine, and cortisol levels were associated with higher ratings of stress and tired, and with lower ratings of happy. Phase of the menstrual cycle and the day factor (work day, off day) were also associated with mood differences, and the direction of the effects depended on hormone levels and hormone sampling period. Conclusion: The experience of moods is affected by arousal-related interaction of hormone levels with phase of the menstrual cycle and occupational stress
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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