Conclusion: The results suggest that ASD children have deficits in attentional and inhibitory control. Frontal dysfunction and weak ACC engagement in ASD were supported as the underlying neuronal inefficiency. / Methods: 20 children with high-functioning ASD [Mean Age (SD): 10.75 years old (2.07 years); Mean IQ (SD): 101.4 (16.8)] and age- and IQ-matched normal children (NC) [Mean Age (SD): 9.80 years old (1.88 years); Mean IQ (SD): 110.7(17.8)] were investigated electrophysiologically during performance of a visual Go/NoGo task. An electrophysiological source localization method was employed to further analyze the data. Several different neurospsychological tests were also performed to provide behavioral measures on attention and inhibition. / Objectives: To investigate neurophysiologic abnormalities in frontal and anterior cingulate cortex underlying attentional and inhibitory control in children with Autism Spectrum Disorder (ASD). / Results: ASD children showed a significantly task-related lower frontal theta activity. This effect was associated with a significantly reduced activation of the anterior cingulate cortex (ACC). Both groups also differ significantly regarding the behavioral aspects of attention and inhibition. / Leung, Shuk Yin Connie. / "November 2009." / Adviser: Chan Sue-Yin Agnes. / Source: Dissertation Abstracts International, Volume: 72-01, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 65-85). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese.

Representing a major public health concern, suicide is a leading cause of death worldwide. Generally regarded as a behavior with a multitude of state and trait dependent risk factors (e.g. psychiatric disorders, substance abuse, genetics), explanations as to why certain individuals commit suicide while others do not are complex. Of interest is in studying potential trait dependent variables involved in the neurobiology of suicide, particularly at the cellular level. Knowledge of the cellular integrity may aid in explaining the observed macroscopic alterations and ultimately the behavioral correlates associated with suicidality. Therefore we set out to summarize extant knowledge of the cellular alterations occurring in the brains of major depressive and suicide individuals. Following this, we conducted our own cellular investigation in a region known to be altered in major depression and suicide, a supracallosal area of BA24a. Neuronal and glial cell densities as well as neuronal cell sizes were assessed in upper and lower cortical layers between sudden-death controls and MDD suicide subjects. Secondary analyses were also conducted to examine the effect of alcohol on depressed suicides. Analyses of cell densities and neuronal soma sizes between controls and MDD suicide subjects did not reveal any significant differences. Further analyses showed increased glial cell densities in alcoholic depressed suicides. Future studies are necessary to examine explicit changes in the cellular compositions occurring in alcoholic dependent individuals. Staining techniques aimed at targeting specific subtypes of neurons and glial cells will help determine if these cell populations do in fact have an influential role in suicide and MDD.

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