As a Window on the Brain
In 2002 Jamshed Bharucha, PhD, began a new phase of his career as provost and senior vice president of Tufts University. Before coming to Tufts he was a teacher, researcher, and administrative official at Dartmouth College. He graduated Phi Beta Kappa from Vassar College, where he majored in biopsychology, received an MA in philosophy from Yale University, and a PhD in cognitive psychology from Harvard University. Bharucha is interested in the brain, the relationship between the brain and the mind, and how the brain enables mental phenomena.
An accomplished musician, Bharucha began studying the cognitive aspects of music in the early 1980s, and started using music to study the brain around 1990. It was at this time that he began collaborating with neurologist Mark Tramo, studying patients who had had selective brain damage from strokes or from neurosurgical procedures. "We would try to see what musical deficits they had," said Bharucha. "That's really when magnetic resonance imaging (MRI) came into extensive use, and I jumped into that." Cognitive psychologists became interested in a variant of MRI, called functional MRI, which looks at brain activity rather than brain structure.
General principles of cognition suggest that the plasticity of the brain enables it to learn. "The brain figures out what is regular about this environment, encodes those regularities, and then uses those patterns as filters to perceive the world going forward. That's how perception becomes facilitated so that predictable things are processed quickly, freeing up conscious resources for unexpected or unfamiliar things."
One of Bharucha's interests is using computational neural net models of learning combined with functional MRI to try to show retrospectively that there might have been plasticity. "We have an ongoing cross-cultural study in which people who have grown up in different cultures we used Indian and American people listen to the same piece of music or the same samples of speech. Depending on whether the music or the speech is culturally familiar or not, we look to see if there are different patterns of activation in the brain."
"In the case of language, just looking at the temporal lobe, which is where the auditory cortex is, we found a much greater extent of activation when listening to a familiar language than when listening to an unfamiliar language, and that implies plasticity that the connections between neurons get stronger or weaker or new connections may form or some might fall off in the course of learning."
With music, Bharucha hasn't found any systematic differences in either the auditory cortex or the frontal lobe. "Maybe the difference is more distributed throughout the brain and much more subtle, rather than focused on a particular area," he mused. Using a pattern recognition analysis, Bharucha looked at the extent of activation in 16 brain regions for each of the subjects. "You can create a vector or an array out of those 16 numbers and correlate this 16-element vector of each subject with each other subject, and you get an inter-subject correlation matrix that shows how close any pair of subjects are in their brain activity. You put this through an algorithm called multi-dimensional scaling, which takes a multi-dimensional space, in this case 16 dimensions, and tries to reduce it to a minimum number of dimensions. In this case we were able to see that in two dimensions, the subjects separate themselves out very nicely, the Indian and American subjects." The data suggest that cultural space maps into the brain in some way.
Bharucha is still settling in to his new laboratory at Tufts. He wants to focus on the projects that are already up and going and make sure that his graduate student is successful and fully launched. While the only collaborator he is actively seeking right now is someone to do the technical side of functional MRI, he is looking forward to future collaborations with people in the Boston area.
For more information, go to http://www.neurosci.tufts.edu/bharucha/.