Dr. Alessandra M. Passarotti

My main research interest is to investigate the cognitive and neurological underpinnings of attention and visuo-spatial processing, from a developmental, cognitive and neuroscience perspective. My continuing goal at Michigan State University is to use an integrated approach to study these issues by combining a variety of research techniques, such as different behavioral paradigms, fMRI (functional magnetic resonance imaging) , and neuropsychological assessments.
During my Ph.D. studies at the University of Illinois, Urbana-Champaign, and The Beckman Institute, I took an innovative approach to the study of attention and visuo-spatial processing by investigating the effects of interhemispheric interaction (IHI) on the overall attentional capacity of the brain. There is a robust body of evidence in the visual modality suggesting that as we increase computational complexity, a division of computations between the two hemispheres can improve attentional performance by increasing the processing capacity of the brain. In my experiments I provided converging evidence in support of this view by showing that the effects of IHI hold across different ways of conceptualizing attention (e.g., attention as processing resources versus attention as selection) and across different types of stimuli. So far, strategies of IHI have been studied in the visual modality. My main contribution in this research area has been to invent a series of paradigms to examine IHI effects in modalities other than the visual one. By demonstrating the benefit of dividing the processing load between the two hemispheres as task complexity increases for both the tactile and auditory modalities, as well as for the visual modality, I showed for the first time that IHI effects are cross-modal.
My research has important implications also from a developmental and clinical perspective. Dr. Banich at U of I and I used some of our paradigms to study the efficiency of IHI in normal children and children with early-treated phenylketonuria (PKU), a genetic disease that disrupts callosal myelination, and presents a cognitive profile of attentional deficits. Our results suggest that different from normal children, PKU children have problems with interhemispheric sharing of information and do not show the usual benefits of dividing processing load across the hemispheres. I also studied how callosal degeneration may affect IHI throughout the lifespan. In a major project with a local hospital we examined how degeneration of different areas of the corpus callosum in Multiple Sclerosis affects IHI and attention in the visual, auditory, and tactile modalities. Given the evidence that the two hemispheres can couple their processes to increase computational power, the next relevant question I wish to address is whether the hemispheres can also decouple, or insulate, their processes and work independently to reduce cross-talk and interference. My doctoral dissertation work provided one of the first pieces of evidence that insulation of task-irrelevant information across-hemispheres occurs when processing demands on one hemisphere are relatively low. However, as processing demands increase interchange of the interfering information occurs, possibly because one hemisphere tries to recruit more resources by communicating with the other hemisphere.
My post-doctoral tenure at the University of California, San Diego, enabled me to continue my research on insulation and selective attention, while giving me the opportunity to expand my research to developmental cognitive neuroscience and pediatric fMRI.
I am currently using fMRI to investigate visuo-spatial and attentional networks in the mature and developing brain. Although the neural bases of object and spatial processing have been extensively investigated with brain imaging techniques in adults, very little is known on the development of the neurological and functional bases of these systems in children. At UCSD I conducted one of the first studies that examines concurrently the development of the ''What'' and ''Where'' neurological pathways, which are involved in object and spatial processing, respectively. I used new face-matching and location-matching paradigms to test children 9 to 11 years old, teenagers and adults. In particular,I examined the degree to which the fusiform area in the inferior temporal lobe, which is typically involved in face processing, is specialized in the developing brain. Interestingly, I found that although fusiform activation was present in all age groups, there was a shift from a more widespread activation in children to a more focal activation in adults. My findings have important implications for theories of face processing and brain development, by showing that the neural system involved in face processing may undergo development and fine-tuning well into late childhood.

At MSU I have established a Developmental Cognitive Neuroscience Laboratory and I am affiliated both with the Cognitive Science and the Neuroscience Program within the Psychology Department. I am currently using fMRI and collaborating with the Dept of Radiology, MSU, to further study the development of the neural bases of attention, working memory and face emotion processing in childhood and adulthood. In particular, in 2003 I carried out a fMRI study to examine the development of the cortical and sub-cortical networks involved in the processing of face expressions, using a task involving selective attention for a target facial emotion. Our findings suggest important developmental differences in the processing of face emotions, that I will continue to explore in the near future. An abstract on the present study was accepted for presentation at the Cognitive Neuroscience Society Conference in April 2004.

Clinical Neuropsychology Experience:

Practicum in Clinical Neuropsychology at the Psychological Services Center of the University of Illinois, Champaign ( 1996-1997).

Pediatric fMRI:
Post-doctoral specialization in Pediatric fMRI at the cognitiveScience Department, University of California, San Diego (1999-2002)

The series of studies I have completed and those I plan to carry out are innovative in their approach to studying the development of attention, hemispheric communication, face processing and visuo-spatial processes. The behavioral and imaging paradigms that I created focus on how different brain systems interact, and they have great potential for being applied to clinical and developmental populations in order to answer critical questions on the development of the neurophysiological bases of attention, visuo-spatial processes, and IHI.

Some of the paradigms I created can be used as converging methods to assess performance in attention and visuo-spatial processing, as well as to test the effects of certain medications on these processes. My studies on how interhemispheric interaction affects attentional processes have relevance for human information processing applications.