STUDIES ON CHOLINERGIC FUNCTION AND MEMORY IN MICE (CHOLINOTOXINS, WORKING, REFERENCE MEMORY, RADIAL ARM MAZE)

Considerable evidence suggests that central cholinergic neurons participate in either acquisition, storage or retrieval of information. Experiments were designed to evaluate information processing in mice following either reversible or irreversible impairment in central cholinergic activity. The cholinergic receptor antagonists, atropine and methylatropine were used to reversibly inhibit cholinergic transmission. Irreversible impairment in central cholinergic function was achieved by central administration of the cholinergic-specific neurotoxins, N-ethyl-choline aziridinium (ECA) and N-ethyl-acetylcholine aziridinium (EACA).^ ECA and EACA appear to act by irreversible inhibition of high affinity choline uptake (proposed rate-limiting step in acetylcholine synthesis). Intraventricular administration of ECA or EACA produced persistent reduction in hippocampal choline acetyltransferase activity. Other neuronal systems and brain regions showed no evidence of toxicity.^ Mice treated with either ECA or EACA showed behavioral deficits associated with cholinergic dysfunction. Passive avoidance behavior was significantly impaired by cholinotoxin treatment. Radial arm maze performance was also significantly impaired in cholinotoxin-treated animals. Deficits in radial arm maze performance were transient, however, such that rapid and apparent complete behavioral recovery was seen during retention testing. The centrally active cholinergic receptor antagonist atropine also caused significant impairment in radial arm maze behavior, while equivalent doses of methylatropine were without effect.^ The relative effects of cholinotoxin and receptor antagonist treatment on short-term (working) memory and long-term (reference) memory in radial arm maze behavior were examined. Maze rotation studies indicated that there were at least two different response strategies which could result in accurate maze performance. One strategy involved the use of response algorithms and was considered to be a function of reference memory. Another strategy appeared to be primarily dependent on spatial working memory. However, all behavioral paradigms with multiple trails have reference memory requirements (i.e. information useful over all trials). Performance was similarly affected following either cholinotoxin or anticholinergic treatment, regardless of the response strategy utilized. In addition, rates of behavioral recovery following cholinotoxin treatment were similar between response groups. It was concluded that both cholinotoxin and anticholinergic treatment primarily resulted in impaired reference memory processes. ^

EVALUATION OF THE EFFECTIVENESS OF ANISOTROPIC ANALYTICAL ALGORITHM IN FLATTENED AND FLATTENING-FILTER-FREE BEAMS FOR HIGH ENERGY LUNG DOSE DELIVERY USING THE RADIOLOGICAL PHYSICS CENTER LUNG PHANTOM

The effectiveness of the Anisotropic Analytical Algorithm (AAA) implemented in the Eclipse treatment planning system (TPS) was evaluated using theRadiologicalPhysicsCenteranthropomorphic lung phantom using both flattened and flattening-filter-free high energy beams. Radiation treatment plans were developed following the Radiation Therapy Oncology Group and theRadiologicalPhysicsCenterguidelines for lung treatment using Stereotactic Radiation Body Therapy. The tumor was covered such that at least 95% of Planning Target Volume (PTV) received 100% of the prescribed dose while ensuring that normal tissue constraints were followed as well. Calculated doses were exported from the Eclipse TPS and compared with the experimental data as measured using thermoluminescence detectors (TLD) and radiochromic films that were placed inside the phantom. The results demonstrate that the AAA superposition-convolution algorithm is able to calculate SBRT treatment plans with all clinically used photon beams in the range from 6 MV to 18 MV. The measured dose distribution showed a good agreement with the calculated distribution using clinically acceptable criteria of ±5% dose or 3mm distance to agreement. These results show that in a heterogeneous environment a 3D pencil beam superposition-convolution algorithms with Monte Carlo pre-calculated scatter kernels, such as AAA, are able to reliably calculate dose, accounting for increased lateral scattering due to the loss of electronic equilibrium in low density medium. The data for high energy plans (15 MV and 18 MV) showed very good tumor coverage in contrast to findings by other investigators for less sophisticated dose calculation algorithms, which demonstrated less than expected tumor doses and generally worse tumor coverage for high energy plans compared to 6MV plans. This demonstrates that the modern superposition-convolution AAA algorithm is a significant improvement over previous algorithms and is able to calculate doses accurately for SBRT treatment plans in the highly heterogeneous environment of the thorax for both lower (≤12 MV) and higher (greater than 12 MV) beam energies.

Lo masivo ante lo diferente : Rituales de interacción y energía emocional en el segmento radial "Da para darse"

Desde el estudio clásico de Bajtin se considera que el sexo es un tópico fuerte de las culturas populares. Este trabajo presenta avances de una investigación en curso sobre el segmento radial "Da para darse" del programa Perros de la calle en FM Metro de Buenos Aires. En él, una persona llama a la radio porque quiere tener sexo ("darse") con otra persona, la cual es llamada en vivo sin saber que está saliendo al aire, y tras conversar con el oyente puede acceder o no. Los datos fueron grabados digitalmente de 17 programas (alrededor de 60 "casos") entre junio y diciembre de 2009, totalizando más de 9 horas de audio, desgrabados y codificados íntegramente. Siguiendo la "teoría de los rituales de interacción" de Randall Collins, esta ponencia se centra en dos categorías emergentes del análisis: las respuestas de lo masivo, encarnado en los conductores, primero, ante "casos" homosexuales o bisexuales; y segundo, ante participantes-"otros" en términos de clase (un joven de clases populares) y procedencia (un cordobés muy excéntrico). La teoría de los rituales de interacción, aunque parecería orientarse a encuentros cara-a-cara, prueba ser útil para analizar este tipo de usos sociales de los medios masivos de comunicación

Lo masivo ante lo diferente : Rituales de interacción y energía emocional en el segmento radial "Da para darse"

Desde el estudio clásico de Bajtin se considera que el sexo es un tópico fuerte de las culturas populares. Este trabajo presenta avances de una investigación en curso sobre el segmento radial "Da para darse" del programa Perros de la calle en FM Metro de Buenos Aires. En él, una persona llama a la radio porque quiere tener sexo ("darse") con otra persona, la cual es llamada en vivo sin saber que está saliendo al aire, y tras conversar con el oyente puede acceder o no. Los datos fueron grabados digitalmente de 17 programas (alrededor de 60 "casos") entre junio y diciembre de 2009, totalizando más de 9 horas de audio, desgrabados y codificados íntegramente. Siguiendo la "teoría de los rituales de interacción" de Randall Collins, esta ponencia se centra en dos categorías emergentes del análisis: las respuestas de lo masivo, encarnado en los conductores, primero, ante "casos" homosexuales o bisexuales; y segundo, ante participantes-"otros" en términos de clase (un joven de clases populares) y procedencia (un cordobés muy excéntrico). La teoría de los rituales de interacción, aunque parecería orientarse a encuentros cara-a-cara, prueba ser útil para analizar este tipo de usos sociales de los medios masivos de comunicación

Estructura discursiva de la entrevista radial

Tabla de contenidos: La noticia como forma de comunicación. La entrevista como género discursivo. Descripción del corpus. Enfoques y temas clave en el análisis de la interacción verbal. La estructura del intercambio. Aproximación al análisis.