Title

Cortical developmental disruption and long-term behavioral outcome: Pathways toward pathology and remediation

Date of Completion

January 2008

Keywords

Biology, Neuroscience|Psychology, Behavioral|Psychology, Developmental

Degree

Ph.D.

Abstract

Disruption of the developing neocortex can lead to a diverse profile of cortical malformations, ranging from clusters of cells in deep cortical layers (heterotopia), to protrusions of cells in the molecular layer (ectopia), and abnormal enfolding and lamination of neocortex (microgyria). Such malformations have been seen in the postmortem brains of human dyslexics (including both ectopia and microgyria), as well as in children with specific language impairments (microgyria). Moreover, such anomalies have been associated with specific reading impairment (e.g., heterotopia). Concurrent animal models have revealed an association between neocortical malformations and subsequent auditory temporal processing deficits, which have in turn been suggested to causally influence a break-down in phonological processing and subsequent word encoding observed in language-learning impaired populations. Specifically, auditory temporal processing deficits manifest as an inability to discriminate rapid acoustic information, and for humans these impairments are typically seen within the tens of milliseconds range critical for the identification of phonemic transitions. In the studies presented here, we examined several factors that could influence and/or exacerbate cortical developmental disruption and long-term auditory processing and learning, using two rodent models of cortical developmental disruption (microgyria & heterotopia). Finally, we evaluated the potential for early acoustic discrimination experience to improve auditory temporal processing beyond improvements seen with normal maturation. ^