Lesions involving the intralaminar thalamic nuclei have been associated with impairments in working memory and intentional motor function in human clinical cases and animal models of amnesia. The intralaminar nuclei have afferent and efferent connections related to striatum. To test whether disruption of striatal function can account for impairments produced by intralaminar lesions, we investigated the effects of striatal lesions on two tasks known to be impaired by intralaminar damage in the rat: radial maze delayed nonmatching (DNM), a measure of spatial working memory, and self-paced serial reaction time (SRT), a measure of intentional response speed. We compared the effects of lesions in four sites: the medial and lateral caudate putamen, nucleus accumbens, and olfactory tubercle. We found that lesions of the medial, accumbens, or tubercle sites impaired DNM performance, and that lesions of the lateral caudate putamen increased choice response time for the SRT task. There was a double dissociation between the effects of the ventral and the lateral lesions on these two tasks. For both tasks, the effects of striatal lesions were qualitatively similar and at least as large as intralaminar lesions in previous studies. These results provide evidence that striatal dysfunction can account for the DNM and SRT impairments produced by intralaminar lesions. The dissociation of functional impairments suggests that lateral sensorimotor areas of caudate putamen are important for responding based on external sensory stimuli and limbic-related areas in ventral striatum are important for responding based on information held in working memory.

In this sample, children given a baseline assessment in a group setting performed no differently than children tested individually when standardized administration procedures were used by trained test administrators. Previous evidence suggesting differences between settings may be attributable to the variability in test administration and supervision rather than the environment itself. The importance of standardized procedures and proper supervision during baseline concussion assessment is supported by these findings.

With the increasing survival of extremely preterm (EP) birth infants in the surfactant era, the longer-term outcome of infants born at the threshold of viability has become a vital topic of study. The goal of this investigation was twofold. First, while taking into account the influence of sociodemographic confounds, we wished to investigate neuropsychological outcome differences between two groups of EP preschoolers: 23-24 weeks (n = 20), and 25-26 weeks' (n = 21) gestation at delivery. Second, we wished to explore whether, within the population of EP preschoolers, gestational maturity accounts for a unique portion of the variance in neuropsychological outcome, over and above the variance explained by ante-, peri-, and neonatal complications, or treatment factors. The findings revealed group differences, ranging from .70 to .80 of a standard deviation in general intellectual abilities, nonverbal intelligence, and global motor performance, in favor of the more mature EP group. Additionally, gestational maturity was found to explain a unique portion of the variance in global intellectual and motor abilities. These findings are interpreted from the perspective that gestational age is an index of the vulnerability of the central nervous system to disruption of developmentally regulated processes.

A significant, yet circumscribed, association was demonstrated between neonatal hypoxic risk, in the VP infant, and neuropsychological outcome assessed in the preschool years.