Lesions of mediodorsal thalamic nucleus cause deficits in attention to changes in environmental cues without causing sensory deficits

Links between abnormal brain structure and cognition in holoprosencephaly

Converging information on medical issues, motor ability, and cognitive outcomes is essential when addressing long-term clinical management in children with holoprosencephaly. This study considered whether adding more informative structural indices to classic holoprosencephaly categories would increase prediction of cognitive outcomes. Forty-two children with holoprosencephaly were examined to determine the association of deep gray nuclei abnormalities with cognitive abilities and the effect of motor skill deficits on cognitive performance. Additionally, a cognitive profile was described using the Carter Neurocognitive Assessment, an experimental diagnostic instrument designed specifically for young children with severe neurodevelopmental dysfunction. Findings indicated that nonseparation of the deep gray nuclei was significantly associated with the cognitive construct of vocal communication, but not with the cognitive constructs of social awareness, visual attention, or auditory comprehension. Importantly, motor skill deficits did not significantly affect performance on the Carter Neurocognitive Assessment. This study is the first investigation to provide a descriptive overview of specific cognitive skills in this group of children. The results also strongly suggest that this feature of the brain's structure does not predict all aspects of neurodevelopmental function. These findings contribute a critical component to the growing body of knowledge regarding the medical and clinical outcomes of children with holoprosencephaly.

Dissociation between conditioned taste aversion and radial maze learning following seizure-induced multifocal brain damage: quantitative tests of serial vs. parallel circuit models of memory

Multivariate analyses between conditioned taste aversion (CTA) and radial maze acquisition (RMA) scores and percentages of neuronal dropout within thalamic and telencephalic structures were completed for rats in which overt seizures had been evoked following a single systemic injection of lithium/pilocarpine. Despite multifocal damage, only the amount of damage within the hippocampus (CA1) and the basolateral amygdala was most strongly associated with attenuated CTA, whereas damage within the mediodorsal thalamus was primarily associated with RMA. There was no significant correlation between CTA or RMA. Multiple regression analyses for specific Paxinos and Watson structures and their traditional aggregates supported more precise delineation of neuronal substrates of learning/memory and a multimodal (parallel) model for these processes.