Master of Philosophy / This thesis investigates the work of Morris Louis (1912-1962) in relation to ‘opticality’, a theory developed by the prominent American art critic Clement Greenberg. Between the late 1930s and 1950s, Greenberg developed a comprehensive argument concerning the opticality, or the optical illusion, of abstract painting. This theory influenced common approaches towards Abstract Expressionist painting during the 1940s and 1950s, culminating in Greenberg’s writing on ‘Colourfield’ painting in major texts of the 1960s such as ‘Louis and Noland’ (1960). Through research into the development of Morris Louis’ technique, including several of his major series as well as lesser known works, this thesis argues that our understanding of Louis’ work has been constricted by a narrow perception of the opticality of his 'stain' paintings, and explores Louis' technique in light of alternative interpretations of his work.

Several studies suggest profound effects on mood and cognition by neuroactive steroids. Estrogen alone or in combination with antidepressant drugs affecting the serotonin system has been used to treat mood disorders. On the other hand, progesterone is related to negative effects on mood and memory. A major part of the progesterone effects on the brain can be mediated by its metabolite allopregnanolone, which is also de novo synthesized in the brain, and affects the GABAA receptors. It would be of great importance to find a substance that antagonize allopregnanolone adverse effects. To investigate how long term supplementation of estradiol and progesterone, resembling postmenopausal hormone replacement therapy, affects serotonin receptors in different brain areas important for mood and memory functions, we used ovariectomized female rats. After 2 weeks of supplementation with 17β-estradiol alone or in combination with progesterone, or placebo pellets, estradiol alone decreases but estradiol supplemented together with progesterone increases 5HT1A mRNA expression in the hippocampus. Estradiol decreases the 5HT2C receptor gene expression, while estradiol in combination with progesterone increases the 5HT2A mRNA expression in the ventral hippocampus. Thus, estradiol alone has opposite effects compared to the estradiol/progesterone combination. To detect if acute tolerance develops to allopregnanolone, an EEG method was used where male rats by continuous allopregnanolone infusion were kept on anesthesia level of the silent second (SS). After different time intervals (first SS, 30 min or 90 min of anesthesia) several GABAA receptor subunit mRNAs were measured for detecting if changed expression of any GABAA receptor subunits is involved in development of acute tolerance. There is development of acute tolerance to allopregnanolone and brain regions of importance are hippocampus, thalamus and hypothalamus. The GABAA receptor alpha4 subunit in thalamus and alpha2 subunit in the dorsal hippocampus are related to development of acute tolerance. For assessing allopregnanolone behavioral effects, we studied how this neurosteroid affects spatial learning in the Morris water maze task Allopregnanolone inhibits spatial learning short after the injection and shows a specific behavioral pattern with swimming close to the pool wall. The steroid UC1011 can inhibit the increase in chloride ion uptake induced by allopregnanolone. UC1011 decreases allopregnanoloneinduced impairment of spatial learning in the water maze, as well as the specific behavioral swim pattern. In conclusion, the present work demonstrates that neuroactive steroids affect the 5HT and GABA systems in a brain region specific way. GABAA receptor subunit changes in hippocampus and thalamus are related to acute allopregnanolone tolerance. Allopregnanolone induces cognitive deficits, like spatial learning impairment and UC1011 can inhibit allopregnanolone-induced effects in vitro and in vivo. Key words: Estradiol, progesterone, HRT, allopregnanolone, UC1011, serotonin receptor, GABAA receptor, mRNA, Morris water maze, silent second, tolerance.

La facilitación del aprendizaje y la memoria por la autoestimulación eléctrica intracraneal (AEIC) se ha observado principalmente en tareas de memoria implícita, como la evitación activa de dos sentidos, en ratas. En este trabajo pretendemos investigar si la AEIC post-entrenamiento, además de facilitar el aprendizaje y la formación de la memoria en paradigmas de memoria implícita, puede facilitar también el aprendizaje y la formación de la memoria en un paradigma de memoria espacial explícita o relacional, hipocampo-dependiente, en el Laberinto Acuático de Morris (LAM), en ratas Wistar. Dado que nuestra investigación previa ha puesto de manifiesto que el efecto de la AEIC para facilitar el aprendizaje y la memoria podría ser sensible a la capacidad básica o inicial de los sujetos para aprender las tareas, en el presente trabajo hemos realizado 4 experimentos consecutivos con ratas Wistar que han sido diseñados para dificultar progresivamente el aprendizaje en el LAM reduciendo, en cada siguiente experimento, la cantidad de ensayos de entrenamiento administrados. En cada experimento, los sujetos se dividieron en dos grupos, grupo AEIC y grupo Control y realizaron, en función del experimento, 8, 5, 3 o 1 ensayo diario. Inmediatamente después de cada sesión de entrenamiento los sujetos del grupo AEIC recibieron el tratamiento de AEIC (2000 trenes de corriente reforzante y estimulante a través de un electrodo crónicamente implantado en el hipotálamo lateral derecho de los sujetos) mientras que los sujetos Control no recibieron tratamiento alguno. Los ensayos tenían una duración de 2 minutos y se iniciaban desde una posición que variaba de uno a otro. Los animales debían nadar en la piscina hasta localizar una plataforma escondida que estaba señalizada por una pelota de playa colocada en la periferia de la piscina en el cuadrante derecho adyacente a la plataforma (experimento 1) o en el cuadrante opuesto al de la plataforma (experimentos 2, 3 y 4). Durante el entrenamiento en esta tarea de plataforma-escondida, registramos la latencia de nado y otras variables como la velocidad media de nado, el tiempo en paredes y la distancia total nadada de cada sujeto. Tres días después de la última sesión de entrenamiento, los sujetos realizaron el ensayo de prueba que consistió en dejar nadar al animal durante 60 segundos con la pelota presente pero sin la plataforma. En este ensayo de prueba registramos la media de tiempo que cada sujeto pasó en cada cuadrante así como las trayectorias de nado. A lo largo de las sesiones de entrenamiento observamos una fuerte y consistente facilitación de la ejecución en el LAM en aquellas ratas que habían recibido el tratamiento de autoestimulación tras un único ensayo de adquisición, es decir, cuando el aprendizaje fue más difícil (experimento 4). En este mismo experimento, durante el ensayo de prueba, los sujetos AEIC nadaron significativamente más tiempo en el cuadrante donde debería haberse encontrado la plataforma que en el resto de zonas de la piscina. Esta facilitación también se observó en la última sesión y en el ensayo de prueba de aquellas ratas que habían realizado tres ensayos por sesión (experimento 3). No obstante, no observamos diferencias entre los sujetos tratados y los controles cuando realizaron 8 o 5 ensayos diarios por sesión (experimentos 1 y 2 respectivamente). Estos hallazgos apoyan y confirman resultados previos de nuestro laboratorio en los que, como hemos comentado anteriormente, observamos que la capacidad de la AEIC post-entrenamiento para facilitar la consolidación de la memoria ha sido y es mayor en sujetos con bajos niveles iniciales de condicionamiento y claramente prueban que este tratamiento es capaz de facilitar la memoria explícita, relacional o hipocampo dependiente. / Learning and memory improvement by post-training intracranial self-stimulation has been observed mostly in implicit tasks, such as active avoidance, in rats. Here we wanted to know whether post-training self-stimulation is also able to facilitate a spatial hippocampus-dependent task in the Morris water maze. Four experiments were run with Wistar rats. In each of them subjects were given at least 5 acquisition sessions, one daily, consisting of two-minute trials. Starting from a variable position, rats had to swim in a pool until they located a hidden platform signalled by a cue located on its opposite site. Each daily session was followed by an immediate treatment of intracranial self-stimulation. Control subjects did not receive the self-stimulation treatment and were placed in their home cage. In the three successive experiments, independent groups of rats were given five, three and one trial per session, respectively. Temporal latencies and trajectories to locate the platform were measured for each subject. Three days after the last acquisition session, the animals were placed again in the pool, for 60 sec, but without the platform and the time spent in each quadrant and the swim trajectories were registered for each subject. A strong and consistent improvement of performance was observed in the self-stimulated rats when they were given only one trial per session, i.e. when learning was more difficult. These findings agree with our previous data showing the capacity of post-training self-stimulation to improve memory especially in rats with low conditioning levels (little training), and clearly prove that post-training self-stimulation can also improve explicit or relational memory.

Fructose consumption has increased exponentially during the past four decades. The physiological effects of a high fructose diet include obesity and insulin resistance. In animal models, the effects of a high fructose diet on fat distribution are inconclusive in that some studies find increases in body mass and lipids while others find no effect. Recent findings indicate that a high fructose diet causes hippocampal insulin resistance in hamsters, raising the possibility that the diet causes impairments in cognition. The following experiments tested the hypotheses that a high fructose diet alters fat distribution rather than total body mass and impairs hippocampal-dependent memory. Results indicated that the high fructose diet did not affect fat distribution, but did increase plasma triacylglycerides. Interestingly, the diet also impaired spatial reference memory in the Morris water maze, and this effect was correlated with plasma triacylglycerides. These results indicate that a high fructose diet impairs brain function.

This document was created in addition to a recital for the seminar Pattern Matching at Chemnitz University of Technology in term 2001/2002. It is a description of basic text search approaches, which are the algorithms of Brute Force, Knuth-Morris-Pratt, Boyer-Moore and Boyer-Moore-Horspool. / Dieses Dokument entstand parallel zu einem Vortrag für das Proseminar Pattern Matching im Wintersemester 2001/2002 an der Technischen Universität Chemnitz. Es stellt die Funktionsweise der grundlegenden Suchalgorithmen Brute Force, Knuth-Morris-Pratt, Boyer-Moore sowie Boyer-Moore-Horspool dar.

Thesis (M.A.)--Memorial University of Newfoundland, 2000. / Bibliography: leaves107-116.

This is a work of moral psychology in the course of which is presented a theory on the nature of guilt. The point of departure is a psychological phenomenon that I call “scrupulousness.” Scrupulousness is present when someone is in doubt about the morality of a minor past action. He or she is obsessively driven to determine whether his act was right or wrong. The result for the individual is vexing preoccupation in a cycle of internal casuistry. I explain this unhappy phenomenon as the result of anxiety over guilt understood as moral staining. A moral stain is a persistent residue adhering to the self created by a past wrongful action. To better explain moral stains, I borrow Christine Korsgaard’s theory of personal identity as constituted by one’s choices. With the aid of Korsgaard’s theory, I then consider how a belief in guilt as moral staining accounts for the worry of the scrupulous person. The Postscript of the Report first considers whether scrupulousness is justified by the explanation I have furnished. I answer this question in the negative. I also consider how anticipation of scrupulous worry could drive a person away from morally ambiguous situations, sometimes preventing him from taking the correct course of action in a form of “moral cowardice.” The Postscript secondly explains the significance of investigating scrupulousness and moral staining for philosophers. I argue that moral staining captures important aspects of the phenomenology of guilt and that it correctly accounts for the reality of guilt as more than a mere psychological state or feeling. To exhibit these strengths of the moral staining view, I compare and criticize Herbert Morris’ prominent model of guilt as consisting in the severance of valued relationships. / text

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