Browsing by Author "Passaro, Antony D."
Now showing 1 - 3 of 3
- Results Per Page
- Sort Options
Item Aberrant spatiotemporal activation profiles associated with math difficulties in children: A magnetic source imaging study(Neuropsychology, 2008-09) Simos, Panagiotis G.; Kanatsouli, Kassiani; Fletcher, Jack M.; Sarkari, Shirin; Juranek, Jenifer; Cirino, Paul T.; Passaro, Antony D.; Papanicolaou, Andrew C.The study investigates the relative degree and timing of cortical activation in parietal, temporal, and frontal regions during simple arithmetic tasks in children who experience math difficulties. Real-time brain activity was measured with magnetoencephalography during simple addition and numerosity judgments in students with math difficulties and average or above average reading skills (MD group, N = 14), students with below average scores on both math and basic reading tests (MD/RD group, N = 16) and students with above average scores on standardized math tests (control group, N = 25). Children with MD showed increased degree of neurophysiological activity in inferior and superior parietal regions in the right hemisphere compared to both controls and MD/RD students. Left hemisphere inferior parietal regions did not show the expected task-related changes and showed activity at a significant temporal delay. MD students also showed increased early engagement of prefrontal cortices. Taken together, these findings may indicate increased reliance on a network of right hemisphere parietal (and possibly frontal areas as well) for simple math calculations in students who experience math difficulties but perform within normal range in reading.Item Functional disruption of the brain mechanism for reading: Effects of comorbidity and task difficulty among children with developmental learning problems(Neuropsychology, 2011-07) Simos, Panagiotis G.; Rezaie, Roozbeh; Fletcher, Jack M.; Juranek, Jenifer; Passaro, Antony D.; Li, Zhimin; Cirino, Paul T.; Papanicolaou, Andrew C.Objective: The study investigated the relative degree and timing of cortical activation associated with phonological decoding in poor readers. Method: Regional brain activity was assessed during performance of a pseudoword reading task and a less demanding, letter-sound naming task by three groups of students: children who experienced reading difficulties without attention problems (N = 50, RD) and nonreading impaired (NI) readers either with (N = 20) or without attention-deficit/hyperactivity disorder (ADHD; N = 50). Recordings were obtained with a whole-head neuromagnetometer, and activation profiles were computed through a minimum norm algorithm. Results: Children with RD showed decreased amplitude of neurophysiological activity in the superior temporal gyrus, bilaterally, and in the left supramarginal and angular gyri during late stages of decoding, compared to typical readers. These effects were restricted to the more demanding pseudoword reading task. No differences were found in degree of activity between NI and ADHD students. Regression analyses provided further support for the crucial role of left hemisphere temporoparietal cortices and the fusiform gyrus for basic reading skills. Conclusions: Results were in agreement with fMRI findings and replicate previous MEG findings with a larger sample, a higher density neuromagnetometer, an overt pseudoword reading task, and a distributed current source-modeling method.Item The timing and strength of regional brain activation associated with word recognition in children with reading difficulties(Frontiers in Neuroscience, 2011-05) Rezaie, Roozbeh; Simos, Panagiotis G.; Fletcher, Jack M.; Juranek, Jenifer; Cirino, Paul T.; Li, Zhimin; Passaro, Antony D.; Papanicolaou, Andrew C.The study investigates the relative degree and timing of cortical activation across parietal, temporal, and frontal regions during performance of a continuous visual-word recognition task in children who experience reading difficulties (N = 44, RD) and typical readers (N = 40, NI). Minimum norm estimates of regional neurophysiological activity were obtained from magnetoencephalographic recordings. Children with RD showed bilaterally reduced neurophysiological activity in the superior and middle temporal gyri, and increased activity in rostral middle frontal and ventral occipitotemporal cortices, bilaterally. The temporal profile of activity in the RD group, featured near-simultaneous activity peaks in temporal, inferior parietal, and prefrontal regions, in contrast to a clear temporal progression of activity among these areas in the NI group. These results replicate and extend previous MEG and fMRI results demonstrating atypical, latency-dependent attributes of the brain circuit involved in word reading in children with reading difficulties.