Education & Certifications
Doctor of Philosophy, University of Southern California, Developmental Psychology (2008)
BA, Temple University, Psychology (2002)
Reading is a complex process involving recruitment and coordination of a distributed network of brain regions. The present study sought to establish a methodologically sound evidentiary base relating specific reading and phonological skills to neuro-metabolic concentration. Single voxel proton magnetic resonance spectroscopy was performed to measure metabolite concentration in a left hemisphere region around the angular gyrus for 31 young adults with a range of reading and phonological abilities. Correlation data demonstrated a significant negative association between phonological decoding and normalized choline concentration and as well as a trend toward a significant negative association between sight word reading and normalized choline concentration, indicating that lower scores on these measures are associated with higher concentrations of choline. Regression analyses indicated that choline concentration accounted for a unique proportion of variance in the phonological decoding measure after accounting for age, cognitive ability and sight word reading skill. This pattern of results suggests some specificity for the negative relationship between choline concentration and phonological decoding. To our knowledge, this is the first study to provide evidence that choline concentration in the angular region may be related to phonological skills independently of other reading skills, general cognitive ability, and age. These results may have important implications for the study and treatment of reading disability, a disorder which has been related to deficits in phonological decoding and abnormalities in the angular gyrus.
View details for DOI 10.1016/j.neuroimage.2012.10.092
View details for Web of Science ID 000314144600017
View details for PubMedID 23147236
Ventricular assist devices (VADs) have been associated with high rates of neurologic injury in pediatric patients during the period of support, but the delayed consequences of this type of injury have not been described in the literature.In this study we assess cognitive outcomes with indices of general intellectual functioning, including working memory, processing speed, perceptual reasoning and verbal comprehension, for pediatric heart transplant recipients who required VAD support as a bridge to transplant (n = 9). We present an aggregate of these VAD patients combined with heart transplant recipients who did not require mechanical circulatory support (n = 11), and compare the performance of all transplant patients (n = 20) to typically developing, healthy comparators (n = 12). We also present a post hoc analysis of those transplant recipients with significant medical morbidity in the first year of life, referred to as the "high-risk" transplant group (n = 5), and compare them with the "low-risk" transplant group (n = 15) and the typically developing comparators (n = 12).The mean performance of the VAD patients was in the average range for each of the examined indices of cognitive functioning. A total of 11% of the VAD patients performed in the impaired range and 78% performed in the average range, with 11% in the superior range on measures of general intellectual functioning. The typically developing participants performed significantly better than the aggregated transplant recipients on all indices except verbal comprehension. Lower cognitive performance in the combined transplant group appears to be associated with medical morbidity in the first year of life.Despite significant neurologic risk factors, this cohort of pediatric patients who were bridged to transplant with VAD demonstrated resiliency in terms of cognitive outcomes. In this heterogeneous population, it is likely that multiple factors contributed to the cognitive outcomes. As VAD use becomes more common in pediatric patients, a prospective evaluation of cognitive outcomes is warranted.
View details for DOI 10.1016/j.healun.2012.11.006
View details for Web of Science ID 000314445800006
Many women with breast cancer, especially those treated with chemotherapy, experience cognitive decline due in part to neurotoxic brain injury. Recent neuroimaging studies suggest widespread brain structural abnormalities pointing to disruption of large-scale brain networks. We applied resting state functional magnetic resonance imaging and graph theoretical analysis to examine the connectome in breast cancer survivors treated with chemotherapy relative to healthy comparison women. Compared to healthy females, the breast cancer group displayed altered global brain network organization characterized by significantly decreased global clustering as well as disrupted regional network characteristics in frontal, striatal and temporal areas. Breast cancer survivors also showed significantly increased self-report of executive function and memory difficulties compared to healthy females. These results suggest that topological organization of both global and regional brain network properties may be disrupted following breast cancer and chemotherapy. This pattern of altered network organization is believed to result in reduced efficiency of parallel information transfer. This is the first report of alterations in large-scale functional brain networks in this population and contributes novel information regarding the neurobiologic mechanisms underlying breast cancer-related cognitive impairment.
View details for DOI 10.1016/j.nbd.2012.07.009
View details for Web of Science ID 000309694000007
View details for PubMedID 22820143
The involvement of the left hemisphere occipito-temporal (OT) junction in reading has been established, yet there is current controversy over the region's specificity for reading and the nature of its role in the reading process. Recent neuroimaging findings suggest that the region is sensitive to orthographic familiarity [Kronbichler, M., Bergmann, J., Hutzler, F., Staffen, W., Mair, A., Ladurner, G., Wimmer, H. 2007. Taxi vs. Taksi: on orthographic word recognition in the left ventral occipito-temporal cortex. Journal of Cognitive Neuroscience 19, 1-11], and the present study tested that hypothesis. Using fMRI, the OT region and other regions in the reading network were localized in 28 adult, right-handed participants. The BOLD signal in these regions was measured during a phonological judgment task (i.e., "Does it sound like a word?"). Stimuli included words, pseudohomophones (phonologically familiar yet orthographically unfamiliar), and pseudowords (phonologically and orthographically unfamiliar) that were matched on lexical properties including sublexical orthography. Relative to baseline, BOLD signal in the OT region was greater for pseudohomophones than for words, suggesting that the region is sensitive to orthographic familiarity at the whole-word level. Further contrasts of orthographic frequency within the word condition revealed increased BOLD signal for low- than high-frequency words. Specialization in the OT region for recognition of frequent letter strings may support the development of reading expertise. Additionally, BOLD signal in the OT region correlates positively with reading efficiency, supporting the idea that this region is a skill zone for reading printed words. BOLD signal in the IFG and STG correlates negatively with reading efficiency, indicating that processing effort in these classic phonological regions is inversely related to reading efficiency.
View details for DOI 10.1016/j.neuroimage.2007.10.044
View details for Web of Science ID 000253241800047
View details for PubMedID 18180168
The integrity of phonological representation/processing in dyslexic children was explored with a gating task in which children listened to successively longer segments (gates) of a word. At each gate, the task was to decide what the entire word was. Responses were scored for overall accuracy as well as the children's sensitivity to coarticulation from the final consonant. As a group, dyslexic children were less able than normally achieving readers to detect coarticulation present in the vowel portion of the word, particularly on the most difficult items, namely those ending in a nasal sound. Hierarchical regression and path analyses indicated that phonological awareness mediated the relation of gating and general language ability to word and pseudoword reading ability.
View details for DOI 10.1016/j.jecp.2007.01.005
View details for Web of Science ID 000247704900002
View details for PubMedID 17359994