No description available.

The ability to generate different responses, and the ability to inhibit inappropriate behaviour, were explored in patients with unilateral cerebral excisions. Site-of-lesion effects were found to interact with the sex of the subject, the time of test-administration, and the nature of the response criteria. In Part I, the Thurstone Word Fluency Test revealed impairments two weeks postoperatively in patients with frontal, temporal, or central-area lesions. In men, removals from the left cerebral hemisphere caused greater deficits than removals from the right, but only left central-area excisions resulted in long-lasting impairments. Patients with left frontal-lobe removals produced few words on a sentence-completion fluency task, but on visual-image fluency, no patient-group was impaired. In Part II, an inability to inhibit impulsive actions on risk-taking tasks was seen after frontal lobectomy, as was a tendency to disregard the instructions on a word-fluency task. These results are consistent with the fact that patients with frontal-lobe lesions described themselves on a behavioural-trait questionnaire as less flexible and more impulsive than did control subjects.

Thesis (Ph.D.)--University of Texas at Dallas, 2008. / Includes vita. Includes bibliographical references (leaves 187-189)

published_or_final_version / Psychology / Master / Master of Philosophy

No description available.

Trabajo de Investigación Requisito para optar al Título de Cirujano Dentista / Autor no autoriza el acceso a texto completo de su documento / El presente trabajo corresponde a un estudio realizado con el fin de analizar la variabilidad morfológica del seno frontal a través de la radiología digital en un grupo de individuos chilenos de la región metropolitana de entre 15 a 20 años de edad. 69 El estudio fue realizado utilizando 52 radiografías digitales Caldwell en formato DICOM de pacientes de ambos sexos. Se evaluaron las características morfológicas del seno frontal por medio de once parámetros descritos por Yoshino et al posteriormente modificada por Cameriere et al y por Tang et al, y por medio de la superposición de los contornos del seno frontal. También se evaluó la existencia de diferencias morfológicas por género y edad en la muestra estudiada. Se concluyo que los individuos de entre 15 a 20 años de edad presentan características morfológicas diferentes estadísticamente significativas, no pudiéndose encontrar dos senos frontales que sean iguales. Además se determinó que las características morfológicas del seno frontal no presentan diferencias estadísticamente significativas entre hombres y mujeres ni tampoco entre los distintos grupos de edades de la muestra estudiada.

No description available.

In a multi‐agent environment, animals must often adopt a stochastic mixed‐strategy approach to maximize reward and minimize costs; otherwise, competitive opponents can exploit predictable choice patterns. This thesis tested the hypothesis that the frontal eye field (FEF) are involved in selecting mixed‐strategy saccades. To this end, I recorded preparatory activity of single FEF neurons and manipulated the preparatory activity of neuronal ensembles within the FEF while a monkey played an oculomotor version of the mixed­‐strategy game ‘matching­‐pennies’. Each trial began with fixation on a central visual stimulus which was extinguished for a predetermined warning period before two targets were presented; one in the center and the other opposite the neuron’s response field. If both the monkey and the adaptive computer opponent chose the same target, the monkey received a liquid reward; otherwise the monkey received no reward for that trial. Like humans, monkeys chose each target in equal proportions but showed a ‘win‐stay’ bias in their choice patterns. Signal detection theory was used to analyze how accurately FEF preparatory activity predicted upcoming saccade choices. My data demonstrates that the accuracy by which FEF preparatory activity predicted upcoming strategic choices gradually increased as the time of saccade execution approached. This pattern of preparatory activity is consistent with an accumulation of evidence for each potential option towards a decision threshold. Subthreshold micro­‐stimulation biased mixed‐strategy saccadic choices, further suggesting a role for the FEF in choosing mixed­‐strategy saccades, albeit unexpectedly, in favor of saccades opposite the stimulation sites. Lastly, a particular advantage of my experiment is that the same monkey performed this task using neurophysiological experimentation in the FEF and intermediate layers of the superior colliculus (SCi). This allowed me to compare the timing and magnitude of neuronal selectivity and effects of subthreshold microstimulation across these two structures, during strategic decision‐making. My results indicate that the selection of mixed­‐strategy saccades occurred earlier and was greater in magnitude in the FEF compared to the SC, indicative of a decision process that occurs earlier in the frontal cortex before being relayed on to premotor regions in the midbrain. / Thesis (Master, Neuroscience Studies) -- Queen's University, 2012-03-28 10:57:30.638

No description available.

No description available.