Ben Cipollini

I would like to understand how the brain computes.  We have an extremely good idea how synapses compute, some basic ideas about how long-distance projections interact, and few general ideas about intra-columnar computation, inter-columnar interactions, and the coordination of these types of information processing.

I address these issues through studies of hemispheric asymmetry and hemispheric communication.  The corpus callosum, the major connective tract between left and right cerebral hemispheres, is the best studied long-distance projection system in the brain.  It generally connects homotopically (an area in one hemishere tends to connect to its homologue in the other hemisphere).  Therefore, studying asymmetries between the hemispheres--and their interactions across the corpus callosum--can help inform us about local processing, long-distance projections, and their interactions.

My research uses neural network modeling to tie a specific asymmetry in grey matter "horizontal" connectivity to differences in visual processing between the hemispheres.  Generally speaking, the left cerebral hemisphere (LH) shows processing advantages for small, local-level aspects of a stimulus; the right cerebral hemisphere (RH) shows advantages for larger, global/gestalt-level aspects of a stimulus.  

In my current project, I aim to show that interactions between the hemispheres, at different levels of processing, can explain behavioral data for stimuli presented at fixation, when both hemispheres are active and must collaborate to identify a stimulus.   I have incorporated interhemispheric connections and timing into the model that follows two basic principles of the corpus callosum: that early sensory areas connect with fast, sparse, topographic connections along the shared middle portion of left and right halves, and that later association areas connect with slower, more numerous, and more diffuse connections.

With this research, I hope to answer questions such as: if chimpanzee and human cerebral hemispheres are as asymmetric as each other, might the smaller brain size (and therefore smaller communication delays) mask many asymmetries in chimpanzee cognitive function?  If yes, then it is possible that some or all of the hemispheric asymmetries found in humans are not unique to humans.  If no, then we have further evidence of the importance of hemispheric asymmetry in the human phenotype.