The graduation thesis discusses positive and negative utilization of media, particularly computers, computer games and the internet, by children. The objective of this thesis is to propose how to attend to the risks of excessive usage of computers and the internet by children.

O córtex pré-frontal medial ventral (CPFMv) é uma estrutura límbica que está envolvida em respostas autonômicas associadas a reações aversivas. O CPFMv é dividido em córtex pré- límbico (PL), córtex infralímbico (IL) e córtex dorsopeduncular (DP). A estimulação elétrica ou química destas regiões causa respostas defensivas e alterações autonômicas tais como respostas cardiovasculares, dependendo da sub-região estimulada. O estresse de restrição (ER) causa alterações hormonais e respostas autonômicas, tais como aumento de pressão arterial (PA) e frequência cardíaca (FC). A ativação de neurônios presentes no CPFMv durante essa situação aversiva, assim como os resultados da inibição farmacológica das sinapses presentes no PL e IL sugerem o envolvimento destas estruturas na modulação das respostas cardiovasculares causadas pelo ER. Entretanto, os possíveis neurotransmissores presentes no vCPFM, envolvidos nesta modulação, ainda não foram elucidados. O sistema opioidérgico central modula o sistema cardiovascular inclusive durante situações aversivas, sendo que tanto receptores quanto peptídeos opióides estão presentes no CPFMv. Considerando o exposto acima, a hipótese a ser testada no presente trabalho foi que a neurotransmissão opioidérgica do PL e IL está envolvida na modulação das respostas cardiovasculares de aumento da PA e FC desencadeadas pelo ER. Assim, a administração de naloxona (antagonista não-seletivo de receptores opióides) no PL ou IL reduziu a resposta pressora e taquicardíaca induzida pelo ER, sendo o perfil da curva dose-inibição em forma de U-invertido. A administração de CTAP (antagonista dos receptores opióides µ) ou nor-BNI (antagonista dos receptores opióides ?) no PL também reduziu a resposta pressora e taquicardíaca induzida pelo ER, de forma semelhante à naloxona, sugerindo o envolvimento desses receptores na modulação das respostas cardiovasculares desencadeadas pelo ER, enquanto que no IL, apenas a administração de nor-BNI reduziu a resposta cardiovascular induzida pelo ER. O tratamento com naltrindole (antagonista ?-seletivo) em ambas as estruturas não alterou a resposta pressora e taquicardíaca gerada pelo ER. A administração de UPF-101 (antagonista ORL-1) no PL potencializou a resposta taquicardíaca, sem alterar a resposta pressora enquanto a administração no IL não gerou efeito. Em resumo, os resultados indicam que o sistema opioidérgico, presente no PL e IL, desempenha papel facilitatório sobre as respostas cardiovasculares induzidas pelo ER, enquanto o sistema nociceptina/orfanina FQ apresentaria papel inibitório. / The ventral medial prefrontal cortex (vMPFC) is a limbic structure involved in the mediation of autonomic responses associated to aversive situations. The vMPFC is divided into prelimbic cortex (PL), infralimbic cortex (IL) and dorsal peduncular cortex (DP). The electrical or chemical stimulation of these regions cause defensive responses and autonomic changes, such as cardiovascular responses, depending on the subregion stimulated. The restraint stress (RS) evokes hormonal and autonomic responses, as well as arterial pressure and heart rate increases. Neuronal activation in the vMPFM was reported during this aversive situation, and the pharmacological inhibition of synapses in the PL and IL has suggested the involvement of these structures in the modulation of cardiovascular responses caused by RS. However, the possible neurotransmitters present in vCPFM that are involved in this modulation have not yet been identified. Opioid peptides and their receptors are present in the CPFMv. Furthermore, the central opioid system is known to modulate the cardiovascular system, even during aversive situations. Therefore, the hypothesis of this study was that PL and IL opioid neurotransmission is involved in the modulation of cardiovascular responses caused by RS. Naloxone (opioid nonselective antagonist) administration in PL or IL reduced the pressure and tachycardiac response evoked by RS, with the dose-inhibition curve having an U-inverset shape. Similar to naloxone, the selective µ-opioid antagonist CTAP and the selective ?-opioid antagonist nor-BNI when administered into the PL also reduced the pressor and tachycardiac response induced by RS, thus suggesting an involvement of these receptors in the modulation of cardiovascular responses evoked by RS, while in the IL, only administration of nor- BNI reduced the cardiovascular response induced by RS. In both structures, the treatment with the selective ?-opioid antagonist naltrindole did not affect the pressor and tachycardic response caused by RS. The pretreatment of the PL with the selective ORL-1 antagonist UPF-101 increased the tachycardic response, without affecting the RSevoked pressor, while the administration of UPF-101 into the IL did not affect the RS-evoked cardiovascular response. In summary, the opioid system in PL and IL appear to play a facilitatory role on the cardiovascular responses induced by RS, while the system nociceptin / orphanin FQ would have an inhibitory role on these responses.

Syfte: Syftet med studien är att undersöka om hållbarhetsrapporter används som ett kommunikationsverktyg i lika stor utsträckning vid mediala företagsskandaler som det görs i allmänhet genom att kommunicera ut såväl positiv som negativ information till företagets intressenter. Metod: Undersökningen har genomförts med en kvalitativ forskningsansats där en kvalitativ innehållsanalys har genomförts på insamlad sekundärdata i form av hållbarhetsrapporter från fyra företag. Empiri: Av empirin framgår en presentation av de fyra granskade bolagen. Där redogörs en djupgående och detaljerad beskrivning av företagens åtaganden och strategier innan och efter skandalen uppmärksammats i media samt en presentation av varje enskild skandal.Slutsats: Majoriteten av de granskade företagen använder sina icke-finansiella rapporter som ett kommunikationsverktyg vid bolagsskandaler för att kunna bemöta de anklagelser som riktats mot dem genom att presentera vidtagna handlingar efter inträffad medial skandal för att på så vis informera sina intressenter och genom detta bevisa sin legitimitet. / Purpose: The purpose of the study is to examine if the sustainability reports are used as a communication tool to the same extent in connection with medial corporate scandals as in general by communicate both positive and negative information to the company’s stakeholders.Method: The study has been conducted with a qualitative research approach where qualitative content analysis has been used to analyze the collected data in the form of the companies sustainability reports.Empiricism: The empiricism shows a presentation of the four audited companies. It outlines a profound and detailed description of the companies commitments and strategies before and after the scandals attention in media and a presentation of each individual scandal.Conclusion: The majority of the audited companies use their non-financial reports as a communication tool in conjunction with corporate scandals to respond at the allegations directed against them by presenting actions taken after the medial scandal to inform their stakeholders and prove their legitimacy.

Schubert's treatment of the medial caesura differs on many levels from that of the Classical tradition. He problematizes many of its norms, introducing complications to the course of his sonata movements. Much research has been devoted to Schubert's approach to sonata form, his large-scale formal deformations as well as his innovative harmonic language. However, few of these writings have discussed the importance of the medial caesura to his sonata forms. Through the lens of Sonata Theory, this dissertation examines Schubert's handling of the MC, demonstrating how the complications derived from his unorthodox practice modify the structural and rhetorical layout of his pieces. I investigate Schubert's approach to three stages surrounding the MC articulation, TR and the energy-gaining process, the MC point of articulation, and the S-theme, discussing specific formal and rhetorical complications that arise from each of them. In chapter 1, I reconsider Schubert's MC practice from a dialogical perspective, demonstrating how some non-normative procedures (in Classical terms) became the norm within his own style. In chapter 2, I examine the impact of two common Schubertian procedures on the function, perception, and meaning of the MC: tonally over-determined TRs and the early arrival of the secondary key within TR. Finally, in chapter 3, I demonstrate how Schubert broadened the available cadential arrangements within MC pairs in declined-MC situations, exploring the expressive potential of normative/non-normative dual oppositions. The conclusion shows that 1) Schubert's stylistic preferences radically expand many of the default procedures posited by Sonata Theory, inviting refinements of the theory; and 2) that the Schubertian MC may incorporate two structural roles beyond its most fundamental function as a formal articulator: clarification of the function of a formally ambiguous passage, which is often connected to cases of tonal over-determination or the early arrival of the secondary key; and introduction of tonal and formal complications into the work's trajectory, invoking some kind of "correction" or compensation.

The current project examined the ability of nicotine to modulate dopamine transporter (DAT) function. Initial experiments determined the dose-response for nicotine to modulate dopamine (DA) clearance in rat striatum and medial prefrontal cortex (MPFC) using in vivo voltammetry and determined if this effect was mediated by nicotinic receptors (nAChRs). In both striatum and MPFC, nicotine increased DA clearance in a mecamylamine-sensitive manner, indicating nAChR-mediation. The effect of acute nornicotine on DAT function was also determined. In contrast to nicotine, nornicotine in a dose-related manner decreased striatal DA clearance in a mecamylamine-sensitive manner, indicating nAChR mediation. To determine if tolerance developed to the nicotine effect nicotine, separate groups of rats were injected once daily for 5 days with nicotine or saline. DA clearance in striatum and MPFC was determined 24 hrs after the last injection. Nicotine increased DA clearance only 10-15% in the group repeatedly administered nicotine, demonstrating that tolerance developed. To determine if nicotine altered striatal DAT efficiency, following nicotine injection, DAT density and maximal velocity of [3H]DA uptake was determined using [3H]GBR12935 binding and saturation analysis of [3H]DA uptake in rat striatum, respectively. Nicotine did not alter the Bmax or Kd of maximal binding of [3H]GBR12935 binding. However, an increase in Vmax was observed at 10 and 40 min following nicotine injection, suggesting that nicotine increases DAT efficiency. To determine if systemic nicotine enhanced DAT function via an action at nAChRs on striatal DA terminals, [3H]DA uptake was determined in striatum in vitro in the absence or presence of nicotine in the buffer. Nicotine did not alter the Vmax for [3H]DA uptake in vitro, suggesting that the nicotine-induced increase in DAT function observed in vivo is mediated by nAChRs on DA cell bodies or another site which indirectly alters DAT function. To determine if the increase in DAT efficiency was due to increased surface expression of striatal DAT, biotinylation and Western blot analyses were performed. Nicotine did not alter striatal DAT, suggesting that the nicotine-induced increase in DA clearance in vivo and DAT efficiency in vitro is not the result of increased trafficking of this protein to the cell surface.

Recent functional neuroimaging evidence suggests that recalling autobiographical memories, imagining fictitious autobiographical episodes, and taking the perspective of another person activate a similar network of brain regions. Results from the two studies presented here provide further evidence of this common neural network. Previous evidence also suggests that recalling autobiographical memories from a first person or from a third person perspective can influence the way in which those memories are experienced as well as the brain regions that are engaged; however, the effect of perspective on imagining autobiographical events remains unclear. Results from Study 1 indicated that brain regions implicated in both remembering and imagining were differentially engaged during these tasks depending on whether a first person or a third person perspective was taken. In addition, while recalling autobiographical memories from a third person perspective can result in the feeling that a past self is more like another person, imagining oneself in the position of another person can result in the feeling that that person is more similar to oneself; this suggests a possible link between perspective in memory and social perspective taking. In Study 2, we identified several brain regions exhibiting a pattern of increasing or decreasing activation as a function of whether socially interactive events were recalled from a first person perspective, by imagining oneself as one's partner, or from a third person perspective (i.e., as a function of distance from one's own perspective). Together, our findings suggest that perspective plays an important role in the way in which brain regions that are part of this common neural network are engaged during memory, imagination, and socially interactive tasks.

The effects of auditory efferent activity on peripheral physiology may be examined by presenting broadband noise (BBN) to the contralateral ear during otoacoustic emission (OAE) recordings. The presentation of BBN typically produces a reduction of OAE amplitudes in comparison to a condition without BBN. This is termed contralateral suppression. Limited information exists regarding the effects of contralateral BBN on responses observed at higher levels in the auditory system. The present study employed this paradigm to investigate interactions of attention and laterality on the transient evoked otoacoustic emission (TEOAE), auditory brainstem response (ABR) and cortical auditory evoked potentials (CAEP) P1-N1-P2. TEOAEs were evoked by 60 dB SPL clicks; ABRs and CAEPs were evoked by 60 dB SPL 2.0 kHz tone pips in 15 normally hearing adults. Four conditions were employed for each ear: 1) quiet (no noise); 2) 60 dB SPL contralateral BBN; 3) words (at -3 dB SNR) embedded in 60 dB SPL contralateral BBN while subjects classified words as animal versus food items; 4) words from condition #3 played backwards and embedded in 60 dB SPL contralateral BBN. For TEOAEs: 1) more suppression was evident in the active attention condition than the passive listening conditions and 2) right ear OAE amplitudes for the 8-18 ms time period exhibited more suppression in the presence of BBN for all noise conditions, although this did not meet statistical significance. For the ABR experiment, amplitudes in the noise conditions decreased in all epochs for the right ear, but not for the left. For the CAEP experiment, asymmetries were evident in temporal regions and an effect of contralateral noise was evident. The outcome of this investigation suggests that efferent activation by noise and active attention has diverse modulatory effects on electroacoustic and electrophysiologic responses along the auditory pathway.

Theoretical models of information storage in the brain have suggested that neurons may undergo an experience-dependent tuning or sharpening of their representations in order to maximize the amount of information that can be stored. Changes in the tuning profiles of neurons have been demonstrated to occur when animals must learn perceptual discriminations, however, whether similar changes occur in the absence of behavioral demands is unclear. To address these questions, the activity of simultaneously recorded medial temporal lobe (MTL) neurons was studied in relation to a passive visual recognition memory task. The structure of this task was such that it allowed for a comparison between novelty related responses as well as tuning properties of individual neurons. A total of 565 well isolated single neurons were recorded. The first contribution of this dissertation is the finding of a dissociation between different medial temporal lobe regions such that neurons in temporal area F (TF), but not perirhinal cortex (PRC) or the hippocampus, show an experience-dependent change in their stimulus selectivity. This finding indicates that tuning of stimulus representations may be an effective mechanism for maximizing information storage in some brain regions. The absence of stimulus tuning in higher level association regions (i.e. TF and PRC) suggests that tuning in these regions may be disadvantageous due to the need to construct unified representations across sensory modalities. A complimentary question to the question of network storage capacity is how networks avoid saturation in the connections between neurons. The second contribution of this dissertation is the finding that there exists a decrease in the magnitude of the short time scale correlations between pairs of neurons; suggesting that networks reduce the number of connections between neurons as a stimulus becomes familiar. Gamma oscillations have been proposed to be the mechanism by which groups of neurons coordinate their activity. However, network coordination has only been indirectly measured. The final contribution of this dissertation is the finding that the magnitude of gamma oscillations is strongly correlated with enhanced magnitude of correlations between neurons.

This thesis explores the role of path integration on the firing of hippocampal place cells and medial entorhinal grid cells. Grid cells fire at equidistant locations in an environment, indicating that they keep track of the distance and direction an animal has moved in an environment. One class of model of path integration uses a continuous attractor network to update position information. The first part of this thesis showed that such a network can generate a "look-ahead" of neural activity that sweeps through the positions just visited and about to be visited, on the short time scale that is observed<italic>in vivo</italic>. Adding intrinsic currents to the neurons in the network model allowed this look-ahead to recur every theta cycle, and generate grid fields of a size comparable to data. Grid cells are a major input the hippocampus, and are hypothesized to be the source of the place specificity of place cells. When an animal explores an open environment, place cells are active in a particular location regardless of the direction in which the animal travels through it. While performing a specific task, such as visiting specific locations in the environment in sequence, however, most place cells are active only in one direction. The second part of this thesis studied the development of this directionality. It was determined that upon the initial appearance of place fields in a novel environment, place cells fired in all directions, supporting the hypothesis that the path integration is the primary determinant of place specificity. The directionality of place fields developed gradually, possibly as a result of learning. Ideas about how this directionality could develop are explored.

Thesis advisor: Michael Numan / Postpartum female rats immediately respond to biological or foster offspring with the display of maternal behavior. In contrast, females that are hysterectomized and ovariectomized on day 15 of pregnancy (15HO) and presented with pups 48 hours later show maternal behavior after 2-3 days of pup exposure. The natural onset of maternal behavior in postpartum females is mediated, in part, by the rise in estradiol just prior to birth. When 15HO rats are administered estradiol benzoate (EB) at the time of HO surgery, 48 hours prior to pup presentation, they show an almost immediate onset of maternal behavior. Presumably, EB administration functions to prime neural circuits which regulate maternal behavior such that these circuits respond to pup presentation with increased maternal responsiveness. Two important neural regions which have been shown to interact in order to promote responsiveness toward infant stimuli are the medial preoptic area (MPOA) and the nucleus accumbens (NA). The following series of studies were undertaken to examine how dopamine (DA) activity within these two important neural sites substitutes for the facilitatory effects of chronic (48 hours) EB stimulation of maternal behavior in 15HO rats. Study 1 investigates whether, in the absence of EB treatment, microinjection of dopamine receptor agonists into either NA or MPOA at the time of pup presentation stimulate maternal behavior in 15HO rats. Study 2 examines the underlying mechanism by which DA receptor stimulation of NA promotes the onset of maternal behavior in 15HO rats. Finally, Study 3 examines the relationship between DA receptor stimulation and estradiol stimulation in the facilitation of maternal responsiveness in 15HO rats. / Thesis (PhD) — Boston College, 2009. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Psychology.