The neural processes generating visual phenomenal consciousness: ERP and neuronavigated brain stimulation studies

One of the greatest conundrums to the contemporary science is the relation between consciousness and brain activity, and one of the specifi c questions is how neural activity can generate vivid subjective experiences. Studies focusing on visual consciousness have become essential in solving the empirical questions of consciousness. Th e main aim of this thesis is to clarify the relation between visual consciousness and the neural and electrophysiological processes of the brain. By applying electroencephalography and functional magnetic resonance image-guided transcranial magnetic stimulation (TMS), we investigated the links between conscious perception and attention, the temporal evolution of visual consciousness during stimulus processing, the causal roles of primary visual cortex (V1), visual area 2 (V2) and lateral occipital cortex (LO) in the generation of visual consciousness and also the methodological issues concerning the accuracy of targeting TMS to V1. Th e results showed that the fi rst eff ects of visual consciousness on electrophysiological responses (about 140 ms aft er the stimulus-onset) appeared earlier than the eff ects of selective attention, and also in the unattended condition, suggesting that visual consciousness and selective attention are two independent phenomena which have distinct underlying neural mechanisms. In addition, while it is well known that V1 is necessary for visual awareness, the results of the present thesis suggest that also the abutting visual area V2 is a prerequisite for conscious perception. In our studies, the activation in V2 was necessary for the conscious perception of change in contrast for a shorter period of time than in the case of more detailed conscious perception. We also found that TMS in LO suppressed the conscious perception of object shape when TMS was delivered in two distinct time windows, the latter corresponding with the timing of the ERPs related to the conscious perception of coherent object shape. Th e result supports the view that LO is crucial in conscious perception of object coherency and is likely to be directly involved in the generation of visual consciousness. Furthermore, we found that visual sensations, or phosphenes, elicited by the TMS of V1 were brighter than identically induced phosphenes arising from V2. Th ese fi ndings demonstrate that V1 contributes more to the generation of the sensation of brightness than does V2. Th e results also suggest that top-down activation from V2 to V1 is probably associated with phosphene generation. The results of the methodological study imply that when a commonly used landmark (2 cm above the inion) is used in targeting TMS to V1, the TMS-induced electric fi eld is likely to be highest in dorsal V2. When V1 was targeted according to the individual retinotopic data, the electric fi eld was highest in V1 only in half of the participants. Th is result suggests that if the objective is to study the role of V1 with TMS methodology, at least functional maps of V1 and V2 should be applied with computational model of the TMS-induced electric fi eld in V1 and V2. Finally, the results of this thesis imply that diff erent features of attention contribute diff erently to visual consciousness, and thus, the theoretical model which is built up of the relationship between visual consciousness and attention should acknowledge these diff erences. Future studies should also explore the possibility that visual consciousness consists of several processing stages, each of which have their distinct underlying neural mechanisms.

ESL students' off-line and on-line texts : differences and similarities /

This study was undertaken to investigate any textual differences and similarities within essays written with a word processing program and an e-mail editor by non-native writers. It arose from many contradictions and a paucity of empirical research within the field of second language learning and electronic technology. To further explore these contradictory observations, 3 classes of intermediate level ESL (English as a Second Language) students v^ote 6 essays, alternating between a word processing program and an e-mail editor. Prior to the data collection, students read brief texts and responded to questions that focused upon three formal topics: immigration, economics, and multiculturalism. Data were examined for (a) the differences in the frequency counts of 12 cohesive devices, (b) sentence complexity, which focused upon the occurrences of simple and complex sentences, (c) the number of words within the writings, (d) the method of contextualization preferred by writers, and (e) any variations in the final grades of the students' texts that resulted from holistic rating. Results of analysis indicated that there were no statistically significant differences in the frequency counts of the linguistic features. Sentence complexity did not vary within the off-line and on-line essays. The average number of words found within the off-line essays was approximately 20% greater than within on-line essays. Contextualization methods were not different within word-processed or e-mailed essays. Finally, there was no difference in the quality of the texts when holistically rated.

Cognitive consequences of expressive suppression : effects of sex and emotional valence

The present research was designed to examine whether sex and/or emotional valence pl aya role in the cognitive consequences (e.g., memory) of expressive suppression. Seventy-two (36 male and 36 female) undergraduates were randomly assigned to either a control or expressive suppression condition, and were asked to watch silent film clips intended to elicit amusement and disgust. While watching each film, participants listened to sixteen nonemotional words. After each film, participants were asked to answer questions about wha t they had seen in the film (visual memory), to recall as many words as they could (auditory recall memory), and to select from a list any words that they had heard during the previous film clip (auditory recognition memory). With regard to the effects of expressive suppression on visual memory, results indicated a 3-way interaction between condition, sex and film emotion: Men performed more poorly than women on the visual memory test after watching both the amusing and disgusting films in the control condition, and when watching the amusing film in the expressive suppression condition. However, men in the expressive suppression condition performed better than women after watching the disgusting film. In terms of the effects of expressive suppression on auditory memory (recognition and recall), a condition x film emotion interaction indicated that there was no difference in auditory memory for the expressive suppression and control conditions when watching the amusing film, but that the expressive suppression group showed poorer auditory memory than the control group for words presented during the disgusting film. Moreover, a ma in effect of sex on auditory memory suggested that men recalled and recognized more words than women across conditions. Taken together, these findings suggest that both sex and the emotional valence of films may influence the effects of expressive suppression on memory. Results will be discussed in the context of previous literature concerning the effects of expressive suppression on cognition.

Structural and functional brain abnormalities in children with subclinical depression

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Encore sexy au cinéma? De la série au film : étude médiatique de la réception de Sex and the City

Après le succès mondial de la série télévisée prolongé par les films, la franchise Sex and the City est devenue un phénomène de masse. Sujet de plusieurs études académiques qui mettent en évidence l’importance du post-féminisme pour le succès de la franchise, Sex and the City se distingue par la relation particulière qui s’instaure entre les spectateurs et les personnages, et qui est l’objet de la présente étude : relation qui passe par la représentation des thèmes et du quotidien féminins et surtout par la construction des personnages, principalement du personnage principal Carrie Bradshaw. De plus, elle est renforcée par des stratégies médiatiques utilisées pour rapprocher le public féminin à partir des processus de reconnaissance et d’identification qui dirigent la réception de masse.

The Erasure of Sex and Gender Minorities in the Healthcare System

Étude de cas / Case study

Un cadre conceptuel pour l'étude des castes en Inde : l'ethnographie Caste and kinship in Kangra réinterprétée dans une optique opérationnelle

Inspiré par la réflexion épistémologique de l'anthropologue Michel Verdon, ce mémoire propose un cadre conceptuel pour l'étude de l'organisation sociale des castes en Inde. L'ethnographie de Jonathan Parry, Caste and Kinship in Kangra, est analysée et réinterprétée dans un langage dit « opérationnel ». Les différentes approches des castes oscillent entre deux pôles théoriques opposés : l'idéalisme, représenté notamment par la démarche structuraliste de Louis Dumont, et le substantialisme, jadis adopté par les dirigeants coloniaux et incarné plus récemment dans les travaux de Dipankar Gupta. Toutes deux holistes, ces options conduisent pourtant à une impasse dans l'étude comparative de l'organisation sociale, car elles rendent les groupes « ontologiquement variables » et, par conséquent, incomparables. En repensant les prémisses sur lesquelles repose la conception générale de l'organisation sociale, un cadre opérationnel confère à la notion de groupe une réalité binaire, discontinue, évitant ainsi la variabilité ontologique des groupes et favorisant le comparatisme. Il rend également possible l'étude des rapports entre groupes et réseaux. La relecture de l'ethnographie Caste and Kinship in Kangra montre la pertinence d'une telle approche dans l'étude des castes. Le caractère segmentaire de ces dernières est remis en cause et l'autonomie des foyers, qui forment des réseaux d'alliances en matière d'activités rituelles, est mise de l'avant. Cette nouvelle description incite enfin à de nouvelles comparaisons.

L-ornithine phenylacetate attenuates increased arterial and extracellular brain ammonia and prevents intracranial hypertension in pigs with acute liver failure.

Hyperammonemia is a feature of acute liver failure (ALF), which is associated with increased intracranial pressure (ICP) and brain herniation. We hypothesized that a combination of L-ornithine and phenylacetate (OP) would synergistically reduce toxic levels of ammonia by (1) L-ornithine increasing glutamine production (ammonia removal) through muscle glutamine synthetase and (2) phenylacetate conjugating with the ornithine-derived glutamine to form phenylacetylglutamine, which is excreted into the urine. The aims of this study were to determine the effect of OP on arterial and extracellular brain ammonia concentrations as well as ICP in pigs with ALF (induced by liver devascularization). ALF pigs were treated with OP (L-ornithine 0.07 g/kg/hour intravenously; phenylbutyrate, prodrug for phenylacetate; 0.05 g/kg/hour intraduodenally) for 8 hours following ALF induction. ICP was monitored throughout, and arterial and extracellular brain ammonia were measured along with phenylacetylglutamine in the urine. Compared with ALF + saline pigs, treatment with OP significantly attenuated concentrations of arterial ammonia (589.6 +/- 56.7 versus 365.2 +/- 60.4 mumol/L [mean +/- SEM], P= 0.002) and extracellular brain ammonia (P= 0.01). The ALF-induced increase in ICP was prevented in ALF + OP-treated pigs (18.3 +/- 1.3 mmHg in ALF + saline versus 10.3 +/- 1.1 mmHg in ALF + OP-treated pigs;P= 0.001). The value of ICP significantly correlated with the concentration of extracellular brain ammonia (r(2) = 0.36,P< 0.001). Urine phenylacetylglutamine levels increased to 4.9 +/- 0.6 micromol/L in ALF + OP-treated pigs versus 0.5 +/- 0.04 micromol/L in ALF + saline-treated pigs (P< 0.001).Conclusion:L-Ornithine and phenylacetate act synergistically to successfully attenuate increases in arterial ammonia, which is accompanied by a significant decrease in extracellular brain ammonia and prevention of intracranial hypertension in pigs with ALF.

AST-120 (spherical carbon adsorbent) lowers ammonia levels and attenuates brain edema in bile duct-ligated rats

The pathogenesis of hepatic encephalopathy is multifactorial, involving gut-derived toxins such as ammonia, which has been demonstrated to induce oxidative stress. Therefore, a primary hepatic encephalopathy treatment target is reducing ammonia production in the gastrointestinal tract. AST-120, an oral adsorbent of engineered activated carbon microspheres with surface areas exceeding 1600 m(2) /g, acts as a sink for neurotoxins and hepatotoxins present in the gut. We evaluated the capacity of AST-120 to adsorb ammonia in vitro and to lower blood ammonia, oxidative stress and brain edema in cirrhotic rats. Cirrhosis was induced in rats by bile duct ligation for 6 weeks. AST-120 was administered by gavage preventively for 6 weeks (0.1, 1, and 4 g/kg/day). In addition, AST-120 was evaluated as a short-term treatment for 2 weeks and 3 days (1 g/kg/day) and as a sink to adsorb intravenously infused ammonium acetate. In vitro, AST-120 efficiently adsorbed ammonia. Ammonia levels significantly decreased in a dose-dependent manner for all AST-120-treated bile duct-ligated rats (nontreated: 177.3 ± 30.8 μM; AST-120, 0.1 g/kg/day: 121.9 ± 13.8 μM; AST-120, 1 g/kg/day: 80.9 ± 30.0 μM; AST-120, 4 g/kg/day: 48.8 ± 19.6 μM) and significantly correlated with doses of AST-120 (r = -0.6603). Brain water content and locomotor activity normalized after AST-120 treatments, whereas arterial reactive oxygen species levels remained unchanged. Furthermore, AST-120 significantly attenuated a rise in arterial ammonia after ammonium acetate administration (intravenously). Conclusion:AST-120 treatment decreased arterial ammonia levels, normalized brain water content and locomotor activity but did not demonstrate an effect on systemic oxidative stress. Also, AST-120 acts as an ammonia sink, efficiently removing blood-derived ammonia. Additional studies are warranted to evaluate the effects of AST-120 on hepatic encephalopathy in patients with advanced liver disease. (HEPATOLOGY 2011;).

Studies,Design and Development of Network Security Enhancement Services Using Novel Cryptographic Algorithms

Internet today has become a vital part of day to day life, owing to the revolutionary changes it has brought about in various fields. Dependence on the Internet as an information highway and knowledge bank is exponentially increasing so that a going back is beyond imagination. Transfer of critical information is also being carried out through the Internet. This widespread use of the Internet coupled with the tremendous growth in e-commerce and m-commerce has created a vital need for infonnation security.Internet has also become an active field of crackers and intruders. The whole development in this area can become null and void if fool-proof security of the data is not ensured without a chance of being adulterated. It is, hence a challenge before the professional community to develop systems to ensure security of the data sent through the Internet.Stream ciphers, hash functions and message authentication codes play vital roles in providing security services like confidentiality, integrity and authentication of the data sent through the Internet. There are several ·such popular and dependable techniques, which have been in use widely, for quite a long time. This long term exposure makes them vulnerable to successful or near successful attempts for attacks. Hence it is the need of the hour to develop new algorithms with better security.Hence studies were conducted on various types of algorithms being used in this area. Focus was given to identify the properties imparting security at this stage. By making use of a perception derived from these studies, new algorithms were designed. Performances of these algorithms were then studied followed by necessary modifications to yield an improved system consisting of a new stream cipher algorithm MAJE4, a new hash code JERIM- 320 and a new message authentication code MACJER-320. Detailed analysis and comparison with the existing popular schemes were also carried out to establish the security levels.The Secure Socket Layer (SSL) I Transport Layer Security (TLS) protocol is one of the most widely used security protocols in Internet. The cryptographic algorithms RC4 and HMAC have been in use for achieving security services like confidentiality and authentication in the SSL I TLS. But recent attacks on RC4 and HMAC have raised questions about the reliability of these algorithms. Hence MAJE4 and MACJER-320 have been proposed as substitutes for them. Detailed studies on the performance of these new algorithms were carried out; it has been observed that they are dependable alternatives.

Implications for early interventionists: Cross-cultural and low-income family differences

This study examined the existing literature on current early intervention processes for children who are deaf or hard of hearing who are from low-income or minority families. The review of literature includes a framework of understanding the dynamics of low-income households and cultural differences among African Americans, Latin Americans, and American Indians.

Effect of sex and genotype on cardiovascular biomarker response to fish oils: the FINGEN Study

Background: The lipid-modulatory effects of high intakes of the fish-oil fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are well established and likely to contribute to cardioprotective benefits. Objectives: We aimed to determine the effect of moderate EPA and DHA intakes (< 2 g EPA + DHA/d) on the plasma fatty acid profile, lipid and apolipoprotein concentrations, lipoprotein subclass distribution, and markers of oxidative status. We also aimed to examine the effect of age, sex, and apolipoprotein E (APOE) genotype on the observed responses. Design: Three hundred twelve adults aged 20-70 y, who were prospectively recruited according to age, sex, and APOE genotype, completed a double-blind placebo-controlled crossover study. Participants consumed control oil, 0.7 g EPA + DHA/d (0.7FO), and 1.8 g EPA + DHA/d (1.8FO) capsules in random order, each for an 8-wk intervention period, separated by 12-wk washout periods. Results: In the group as a whole, 8% and 11% lower plasma triacylglycerol concentrations were evident after 0.7FO and 1.8FO, respectively (P < 0.001): significant sex x treatment (P = 0.038) and sex x genotype x treatment (P = 0.032) interactions were observed, and the greatest triacylglycerol-lowering responses (reductions of 15% and 23% after 0.7FO and 1.8FO, respectively) were evident in APOE4 men. Furthermore, lower VLDL-cholesterol (P = 0.026) and higher LDL-cholesterol (P = 0.010), HDL-cholesterol (P < 0.001), and HDL2 (P < 0.001) concentrations were evident after fish-oil intervention. Conclusions: Supplements providing EPA + DHA at doses as low as 0.7 g/d have a significant effect on the plasma lipid profile. The results of the current trial, which used a prospective recruitment approach to examine the responses in population subgroups, are indicative of a greater triacylglycerol-lowering action of long-chain n-3 polyunsaturated fatty acids in males than in females.

Sex and outcrossing in a sessile freshwater invertebrate

1. The freshwater bryozoan Cristatella mucedo, in common with other sessile, benthic freshwater taxa, has an unusual life history: sex occurs during a relatively brief period near the start of the growing season, and overwintering occurs in the form of asexually produced dormant propagules (statoblasts). Consistent observed heterozygosity (Ho) deficits in C. mucedo populations have previously suggested that inbreeding is common, although a possible contribution of a Wahlund effect to low Ho could not be discounted. 2. We have used microsatellite data in the first study based on codominant markers to genetically characterise maternal colonies and larval offspring of C. mucedo . The 'population' represented by the larvae was in Hardy-Weinberg equilibrium, which has previously been found in only one of 39 populations of C. mucedo . At least 64% of larvae were the products of outcrossing. We suggest that the unusual early timing of sex may be a strategy to maximise rates of outcrossing within populations of sessile freshwater invertebrates.