The development of structure and function in the postnatal human cerebral cortex from birth to 72 months: changes in thickness of layers II and III co-relate to the onset of new age-specific behaviors.

HYPOTHESIS: The thickness of a cortical layer is a composite measure of neuronal, axonal, dendritic, synaptic, and glial numbers and sizes that may relate to thefunction of a cortical area. METHODS: 35 age-specific behaviors with defined cortical localization whose onset lies between birth and 72 months were selected. Each behavior's function localized to one or more of 12 cytoarchitectonic areas (Brodmann areas 4, with homuncular subdivisions for leg, trunk, face, and hand, plus 17, 18, 19, 20, 21, 24, 36, and 37). Data on cortical thickness for each layer of 41 cytoarchitectonic areas (including the 12 above) of the postnatal human cerebral cortex from birth of 72 months were analyzed for general patterns of change. For the 12 cortical areas functionally related to theage-specific behaviors, we searched for layer thickness changes that co-related to when the behaviors began. RESULTS: Without exception, all layers of the 41 cortical areas of the postnatal human cerebral cortex studied develop through a series of repeated thinning and thickening in a wave-like fashion. With regard to the co-relation of behavioral onset and changes in cortical layer thickness, from birth to 15 months, only layer II has agreater than expected frequency of being the layer with the greatest relative change in thickness (relative to its previous value). From 15 to 72 months, only layer IlI has a greater than expected frequency of being the layer with the greatest absolute change in thickness (81% involved a change in its direction of growth (thinning <--> thickening)). The co-occurrence of directional growth change and having the greatest layer thickness change were only statistically significant for layer III when an age-specific behavior began and was not seen for the 41 cortical areas overall (p = 0.014). CONCLUSIONS: Cortical laminar development exhibits aprocess that is mathematically consistent with a random walk with drift and with boundaries so that uncontrolled proliferation and pruning are prevented. The directional changes in layer growth could be controlled by feedback coupled with growth promoting and growth inhibiting factors. Layer II, with its function of establishing local corticocortical connections, appears to be most important in establishing age-specific behaviors of infants from birth to 15 months. Such a process tends to produce relatively simpler behaviors. LayerIII, with its function of establishing longer distance corticocortical connections, appears to be most important in establishing age-specific behaviors of children from 15 to 72 months. This process tends to produce richer, more cross-modal behaviors than those mediated primarily by local corticocortical interactions.

Negative sexual experiences with men among heterosexual women and lesbians.

Abstract Survey responses on traumatic experiences with men were compared from 50 matched pairs of heterosexual women and lesbians. Prior research has implied that lesbians have had more traumatic experiences with men than heterosexual women. The purpose of this study was to test the hypothesis that lesbians would report more negative sexual experiences with men than heterosexual women. The findings of the present study did not support this hypothesis. The only significant difference found between the two groups was that heterosexual women were more likely to report multiple categories of traumatic experiences and lesbians were more likely to report experiences in only one category of trauma. Contrary to prior studies, these results indicate that previous traumatic experiences with men may not be a significant factor in the development of sexual orientation.

Coping with ambiguity in multi-ethnic children of alcoholics.

Visual field dependence in 292 multi-ethnic adult children of alcoholics (ACAs) and nonalcoholics (NACAs) was assessed, using the Hidden Figures Test (Ekstrom, French, & Harmon, 1976). There were no differences among ethnic groups, but ACAs achieved a significantly lower percentage of correct answers and more incorrect answers and attempted more questions relative to NACAs. These findings suggest that ACAs' visuospatial deficits are not related to ethnic and cultural factors.

Spatial learning deficits in adult children of alcoholic parents.

This study investigated whether the visuospatial deficits displayed by chronic alcoholics are present in persons at risk for alcoholism. Participants were 34 matched social drinkers, half of whom were children of alcoholic parents and half of whom had no family alcoholism history. Ss with a family history of alcoholism displayed visuospatial learning that was significantly poorer than that displayed by Ss with no family alcoholism history. The learning patterns displayed by those with a family alcoholism history were similar to those displayed by previously studied detoxified alcoholics and young children of alcoholics using a similar learning task. Data suggest that visuospatial learning deficits may reflect an antecedent to rather than a consequence of chronic alcohol abuse.

Negative sexual experiences with men among heterosexual women and lesbians.

Survey responses on traumatic experiences with men were compared from 50 matched pairs of heterosexual women and lesbians. Prior research has implied that lesbians have had more traumatic experiences with men than heterosexual women. The purpose of this study was to test the hypothesis that lesbians would report more negative sexual experiences with men than heterosexual women. The findings of the present study did not support this hypothesis. The only significant difference found between the two groups was that heterosexual women were more likely to report multiple categories of traumatic experiences and lesbians were more likely to report experiences in only one category of trauma. Contrary to prior studies, these results indicate that previous traumatic experiences with men may not be a significant factor in the development of sexual orientation.

Visuospatial learning in elementary school children with and without a family history of alcoholism.

Chronic alcohol abuse has been consistently associated with cognitive deficits in right-hemisphere-mediated visuospatial operations. Recent evidence indicates that visuospatial deficits may be present in alcoholics prior to the onset of chronic heavy drinking, but it remains unclear whether such deficits are present prior to any alcohol exposure in persons at risk of developing alcoholism. The purpose of this study was to investigate visuospatial information processing in young children with and without a family history of alcoholism. Male and female elementary school children (N = 36), ranging in age from 6 to 11 years, served as participants. Of these children, 18 were from families in which one or both biologic parents had a history of alcoholism. The remaining 18 children had no family history of alcoholism or alcohol-related problems. During a single experimental session, each child received a visuospatial paired-associate learning task, requiring the learning of the spatial positions of five low semantic content "nonsense shapes." The learning performance of the children with a family history of alcoholism was significantly poorer than the performance displayed by the children with no family history of alcoholism. The family history positive children required significantly more trials to learning criterion, gave fewer correct responses and committed more errors. Further, an analysis of response-type frequency relative to the learning trials and analysis of response intercorrelations indicated that the pattern of learning displayed by the children with a family history of alcoholism was similar to that displayed by detoxified alcoholics during a similar learning task.

Proposed model of lesbian identity development: an empirical examination.

A 42-question written survey was administered to 197 women, approximately 96% of whom were self-identified lesbians, for the purpose of gathering information about their experiences from first awareness of lesbian identity to their current status. Descriptive data are presented which seem to suggest that lesbian identity is present prior to the individual's recognition of incongruency between her feelings and those of non-lesbians, and that the process of self-labeling occurs through interaction with the non-lesbian world. The term lesbian identity is discussed and defined. The findings of this study are, in part, described in the framework of a proposed Model of Lesbian Identity Awareness and Self-Labeling which is currently undergoing further investigation.